From 5ff4f5b911294b7841dc2f1154ef9be950139ec4 Mon Sep 17 00:00:00 2001
From: discord9 <discord9@163.com>
Date: Fri, 23 Oct 2026 14:30:51 +0800
Subject: [PATCH 1/2] refactor(datatypes): name the PromQL series label set by
 what it is

`MetricName` held the whole PromQL-visible label set of a series -- the
`__name__` value plus its ordinary labels -- not one metric name. Rename it to
`SeriesLabels` so the type says what it holds, and record in its doc comment
that it is neither a canonical matching/grouping identity nor a storage
identity.

Signed-off-by: discord9 <discord9@163.com>
(cherry picked from commit c69827ae8936d026e2aa93d9b0ba44cbade3d9e2)
---
 src/common/query/src/series_frame.rs          |  4 +-
 .../query/src/series_frame/record_batches.rs  |  8 +--
 src/common/query/src/series_frame/tests.rs    | 12 ++--
 .../query/src/series_frame/tests/lifecycle.rs |  6 +-
 src/datatypes/src/series.rs                   | 12 +++-
 src/datatypes/src/series/frame.rs             |  8 +--
 src/datatypes/src/series/frame/tests.rs       |  8 +--
 src/datatypes/src/series/raw.rs               |  6 +-
 src/datatypes/src/series/raw/tests.rs         |  6 +-
 src/datatypes/src/series/samples.rs           |  6 +-
 src/datatypes/src/series/samples/tests.rs     | 18 +++---
 src/datatypes/src/series/tests.rs             | 16 +++---
 src/datatypes/src/series/time/tests.rs        |  4 +-
 src/mito-codec/src/labels.rs                  |  8 +--
 src/mito2/src/engine/scan_test.rs             |  2 +-
 src/promql/src/aggregate.rs                   | 18 +++---
 src/promql/src/aggregate/state.rs             |  4 +-
 src/promql/src/aggregate/tests.rs             | 27 +++++----
 src/promql/src/evaluated.rs                   |  6 +-
 src/promql/src/extension_plan/fused_series.rs |  2 +-
 .../src/extension_plan/fused_series/tests.rs  | 12 ++--
 .../instant_manipulate/native.rs              |  4 +-
 .../instant_manipulate/native_exec_tests.rs   |  8 +--
 .../instant_manipulate/native_tests.rs        |  6 +-
 src/promql/src/golden.rs                      | 12 ++--
 src/promql/src/grid_series.rs                 | 10 ++--
 src/promql/src/grid_series/reference.rs       | 18 +++---
 src/promql/src/grid_series/tests.rs           |  6 +-
 src/promql/src/histogram_eval.rs              |  8 +--
 src/promql/src/histogram_eval/aggregate.rs    |  4 +-
 src/promql/src/info.rs                        | 10 ++--
 src/promql/src/instant_eval.rs                |  8 +--
 src/promql/src/map.rs                         | 14 ++---
 src/promql/src/map/broadcast.rs               |  4 +-
 src/promql/src/map/tests.rs                   |  6 +-
 src/promql/src/map/tests/broadcast.rs         |  4 +-
 src/promql/src/map/tests/comparison.rs        |  2 +-
 src/promql/src/map_label.rs                   |  4 +-
 src/promql/src/map_time.rs                    |  4 +-
 src/promql/src/native/display.rs              |  4 +-
 src/promql/src/native/display/tests.rs        |  4 +-
 src/promql/src/native/execute.rs              | 14 ++---
 src/promql/src/native/execute/tests.rs        | 56 +++++++++----------
 src/promql/src/native/plan.rs                 |  4 +-
 src/promql/src/range_eval.rs                  |  4 +-
 src/promql/src/range_eval/tests.rs            | 18 +++---
 src/promql/src/select.rs                      | 18 +++---
 src/promql/src/select/tests.rs                | 10 ++--
 src/promql/src/source/merge/tests.rs          |  4 +-
 src/promql/src/source/tests.rs                | 18 +++---
 src/promql/src/vector_match.rs                | 44 +++++++--------
 src/promql/src/vector_match/tests.rs          |  8 +--
 src/promql/tests/native_binary.rs             |  6 +-
 src/query/src/promql/native_compile.rs        |  4 +-
 src/query/src/promql/native_compile/tests.rs  | 12 ++--
 src/store-api/src/region_engine.rs            |  2 +-
 .../region_engine/prepared_series_tests.rs    | 10 ++--
 src/table/src/table/scan/series_tests.rs      |  4 +-
 58 files changed, 290 insertions(+), 279 deletions(-)

diff --git a/src/common/query/src/series_frame.rs b/src/common/query/src/series_frame.rs
index d787106c634..d18cdab86f1 100644
--- a/src/common/query/src/series_frame.rs
+++ b/src/common/query/src/series_frame.rs
@@ -47,7 +47,7 @@ use datatypes::series::frame::{
 };
 use datatypes::series::raw::RawSeriesChunk;
 use datatypes::series::samples::SeriesSchema;
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 use futures_util::Stream;
 use store_api::codec::PrimaryKeyEncoding;
 use store_api::region_engine::{
@@ -380,7 +380,7 @@ struct SequenceValidator {
     ordering: SeriesOrdering,
     previous_key: Option<Vec<u8>>,
     previous_timestamp: Option<i64>,
-    previous_metric: Option<MetricName>,
+    previous_metric: Option<SeriesLabels>,
     previous_is_last: bool,
 }
 
diff --git a/src/common/query/src/series_frame/record_batches.rs b/src/common/query/src/series_frame/record_batches.rs
index 8137f20e004..fa16f16deb3 100644
--- a/src/common/query/src/series_frame/record_batches.rs
+++ b/src/common/query/src/series_frame/record_batches.rs
@@ -32,7 +32,7 @@ use datafusion_common::{DataFusionError, Result as DfResult};
 use datatypes::arrow_array::string_array_value_at_index;
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, Samples, SeriesFields, SeriesSchema};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 use futures_util::Stream;
 use snafu::Location;
 use store_api::region_engine::{RawLabelSource, RawSeriesStream, SendableRawSeriesStream};
@@ -132,8 +132,8 @@ fn validate_mapping(
             return Err(invalid("field must be Float64 or native histogram"));
         }
     }
-    // MetricName validates logical label names and duplicate tags through its canonical path.
-    MetricName::try_new(
+    // SeriesLabels validates logical label names and duplicate tags through its canonical path.
+    SeriesLabels::try_new(
         mapping.metric_name.clone(),
         mapping
             .tags
@@ -274,7 +274,7 @@ impl InputStream {
                 });
             }
         }
-        let metric = MetricName::try_new(metric_name, labels).map_err(codec_error)?;
+        let metric = SeriesLabels::try_new(metric_name, labels).map_err(codec_error)?;
         RawSeriesChunk::try_new(
             &self.schema,
             Buffer::from(key),
diff --git a/src/common/query/src/series_frame/tests.rs b/src/common/query/src/series_frame/tests.rs
index e306fa98ddf..61509c4f12c 100644
--- a/src/common/query/src/series_frame/tests.rs
+++ b/src/common/query/src/series_frame/tests.rs
@@ -32,7 +32,7 @@ use datatypes::arrow::datatypes::{DataType, Schema, SchemaRef};
 use datatypes::arrow::ipc::{reader::StreamReader, writer::StreamWriter};
 use datatypes::arrow::record_batch::RecordBatch;
 use datatypes::series::Label;
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::SeriesOrdering;
 use datatypes::series::frame::{LabelDecodeSpec, RawLabelMode, raw_series_frame_schema};
 use datatypes::series::histogram::{BucketSideView, CounterResetHint, HistogramBatchBuilder};
@@ -59,11 +59,11 @@ fn schema() -> Arc<SeriesSchema> {
         eval_grid: None,
     })
 }
-fn metric() -> MetricName {
-    MetricName::try_new(Some(Arc::from("cpu")), vec![]).unwrap()
+fn metric() -> SeriesLabels {
+    SeriesLabels::try_new(Some(Arc::from("cpu")), vec![]).unwrap()
 }
-fn labeled_metric(host: &str) -> MetricName {
-    MetricName::try_new(
+fn labeled_metric(host: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![Label {
             name: Arc::from("host"),
@@ -76,7 +76,7 @@ fn chunk_with(
     key: &[u8],
     times: &[i64],
     values: Vec<Option<f64>>,
-    metric: Option<MetricName>,
+    metric: Option<SeriesLabels>,
     last: bool,
 ) -> RawSeriesChunk {
     RawSeriesChunk::try_new(
diff --git a/src/common/query/src/series_frame/tests/lifecycle.rs b/src/common/query/src/series_frame/tests/lifecycle.rs
index 54f088a5098..70fe6ede10c 100644
--- a/src/common/query/src/series_frame/tests/lifecycle.rs
+++ b/src/common/query/src/series_frame/tests/lifecycle.rs
@@ -25,7 +25,7 @@ use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{
     DenseSamplesRef, FieldSpec, HistogramSamples, SampleRef, Samples, SeriesFields, SeriesSchema,
 };
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use futures_util::{Stream, StreamExt};
 use store_api::region_engine::{RawLabelSource, RawSeriesStream, SendableRawSeriesStream};
 
@@ -167,7 +167,7 @@ async fn streaming_round_trip_preserves_sliced_multifield_payload_and_owners() {
         &schema,
         Buffer::from(vec![0xaa_u8, 0x10, 0xbb]),
         Some(
-            MetricName::try_new(
+            SeriesLabels::try_new(
                 Some(Arc::from("cpu")),
                 vec![Label {
                     name: Arc::from("host"),
@@ -361,7 +361,7 @@ async fn single_row_sliced_payload_keeps_zero_copy_buffers_and_releases_owners()
             .into(),
         eval_grid: None,
     });
-    let metric = MetricName::try_new(
+    let metric = SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![Label {
             name: Arc::from("host"),
diff --git a/src/datatypes/src/series.rs b/src/datatypes/src/series.rs
index 0de711e2da3..8feba1012dd 100644
--- a/src/datatypes/src/series.rs
+++ b/src/datatypes/src/series.rs
@@ -55,14 +55,20 @@ pub struct Label {
     pub value: Arc<str>,
 }
 
-/// A metric name and its name-sorted ordinary labels.
+/// The PromQL-visible labels of one series: an optional metric name (`__name__`)
+/// plus its name-sorted ordinary labels.
+///
+/// The metric name is only the `__name__` value (see [`Self::name`]); this type is
+/// the whole label set a PromQL series shows. It is neither a canonical
+/// matching/grouping identity (matching drops `__name__` and compares the remaining
+/// labels canonically) nor a storage identity (read key / primary key).
 #[derive(Clone, Debug, PartialEq, Eq)]
-pub struct MetricName {
+pub struct SeriesLabels {
     name: Option<Arc<str>>,
     tags: Arc<[Label]>,
 }
 
-impl MetricName {
+impl SeriesLabels {
     /// Creates a metric name, sorting labels and rejecting duplicates or `__name__` tags.
     pub fn try_new(name: Option<Arc<str>>, mut tags: Vec<Label>) -> Result<Self> {
         tags.sort_unstable_by(|a, b| a.name.cmp(&b.name));
diff --git a/src/datatypes/src/series/frame.rs b/src/datatypes/src/series/frame.rs
index 2dcab10523c..cf1b5a41492 100644
--- a/src/datatypes/src/series/frame.rs
+++ b/src/datatypes/src/series/frame.rs
@@ -76,7 +76,7 @@ use crate::series::raw::{RawSeriesChunk, RawTimestamps};
 use crate::series::samples::{
     DenseSamplesRef, FieldSpec, HistogramSamples, Samples, SeriesFields, SeriesSchema,
 };
-use crate::series::{Label, MetricName, invalid_series};
+use crate::series::{Label, SeriesLabels, invalid_series};
 
 const LAYOUT: &str = "greptime.series.layout";
 const CONTENT: &str = "greptime.series.content";
@@ -735,7 +735,7 @@ pub fn pack_raw_series_chunk(
 /// encoded-size measure.
 struct RawFrameRow {
     primary_key: Buffer,
-    metric: Option<MetricName>,
+    metric: Option<SeriesLabels>,
     is_last: bool,
     times: ScalarBuffer<i64>,
     samples: Vec<Samples>,
@@ -1000,7 +1000,7 @@ fn encode_rows(
     if mode == RawLabelMode::Explicit {
         columns.push(Arc::new(
             rows.iter()
-                .map(|row| row.metric.as_ref().and_then(MetricName::name))
+                .map(|row| row.metric.as_ref().and_then(SeriesLabels::name))
                 .collect::<StringArray>(),
         ));
         let DataType::List(label_item) = schema.field(5).data_type() else {
@@ -1252,7 +1252,7 @@ fn decode_raw_series_frame(
                         value: Arc::from(lv.value(i)),
                     })
                     .collect();
-                Some(MetricName::try_new(
+                Some(SeriesLabels::try_new(
                     (!ns.is_null(row)).then(|| Arc::from(ns.value(row))),
                     tags,
                 )?)
diff --git a/src/datatypes/src/series/frame/tests.rs b/src/datatypes/src/series/frame/tests.rs
index 619db9d3e89..5356ebb84dc 100644
--- a/src/datatypes/src/series/frame/tests.rs
+++ b/src/datatypes/src/series/frame/tests.rs
@@ -28,7 +28,7 @@ use crate::series::histogram::{BucketSideView, CounterResetHint, HistogramBatchB
 use crate::series::samples::{
     DenseSamplesRef, FieldSpec, SampleRef, Samples, SeriesFields, SeriesSchema,
 };
-use crate::series::{Label, MetricName};
+use crate::series::{Label, SeriesLabels};
 
 fn test_schema(names: &[&str]) -> SeriesSchema {
     SeriesSchema {
@@ -43,8 +43,8 @@ fn test_schema(names: &[&str]) -> SeriesSchema {
     }
 }
 
-fn metric(name: Option<&str>, labels: &[(&str, &str)]) -> MetricName {
-    MetricName::try_new(
+fn metric(name: Option<&str>, labels: &[(&str, &str)]) -> SeriesLabels {
+    SeriesLabels::try_new(
         name.map(Arc::from),
         labels
             .iter()
@@ -60,7 +60,7 @@ fn metric(name: Option<&str>, labels: &[(&str, &str)]) -> MetricName {
 fn float_chunk(
     schema: &SeriesSchema,
     key: &[u8],
-    metric: Option<MetricName>,
+    metric: Option<SeriesLabels>,
     times: Vec<i64>,
     values: Vec<Option<f64>>,
     is_last: bool,
diff --git a/src/datatypes/src/series/raw.rs b/src/datatypes/src/series/raw.rs
index da4ba487204..a3d0592b828 100644
--- a/src/datatypes/src/series/raw.rs
+++ b/src/datatypes/src/series/raw.rs
@@ -20,7 +20,7 @@ use snafu::OptionExt;
 
 use crate::error::{InvalidSeriesSnafu, Result};
 use crate::series::samples::{SeriesFields, SeriesSchema};
-use crate::series::{MetricName, invalid_series};
+use crate::series::{SeriesLabels, invalid_series};
 
 /// Strictly increasing source timestamps in milliseconds for a raw series chunk.
 ///
@@ -98,7 +98,7 @@ pub struct RawSeriesChunk {
     pub primary_key: Buffer,
     /// `None` denotes an encoded key under bound-label mode; `Some` contains complete
     /// explicit labels and retains their identity.
-    pub metric: Option<MetricName>,
+    pub metric: Option<SeriesLabels>,
     /// Source timestamps aligned with every field.
     pub time: RawTimestamps,
     /// Field values aligned with the source timestamps.
@@ -116,7 +116,7 @@ impl RawSeriesChunk {
     pub fn try_new(
         schema: &SeriesSchema,
         primary_key: Buffer,
-        metric: Option<MetricName>,
+        metric: Option<SeriesLabels>,
         time: RawTimestamps,
         fields: SeriesFields,
         is_last: bool,
diff --git a/src/datatypes/src/series/raw/tests.rs b/src/datatypes/src/series/raw/tests.rs
index ea2d4f80193..4d4bcc0caac 100644
--- a/src/datatypes/src/series/raw/tests.rs
+++ b/src/datatypes/src/series/raw/tests.rs
@@ -20,7 +20,7 @@ use arrow::buffer::{Buffer, ScalarBuffer};
 use super::*;
 use crate::series::samples::{FieldSpec, SampleRef, Samples, SeriesFields, SeriesSchema};
 use crate::series::time::{EvalGrid, GridSpec};
-use crate::series::{Label, MetricName};
+use crate::series::{Label, SeriesLabels};
 
 fn schema(names: &[&str]) -> SeriesSchema {
     SeriesSchema {
@@ -35,8 +35,8 @@ fn schema(names: &[&str]) -> SeriesSchema {
     }
 }
 
-fn metric() -> MetricName {
-    MetricName::try_new(
+fn metric() -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![Label {
             name: Arc::from("host"),
diff --git a/src/datatypes/src/series/samples.rs b/src/datatypes/src/series/samples.rs
index 2efb63059e7..59e2c862058 100644
--- a/src/datatypes/src/series/samples.rs
+++ b/src/datatypes/src/series/samples.rs
@@ -19,7 +19,7 @@ use arrow::compute::concat;
 use snafu::OptionExt;
 
 use crate::error::{InvalidSeriesSnafu, Result};
-use crate::series::MetricName;
+use crate::series::SeriesLabels;
 use crate::series::histogram::{HistogramBatch, HistogramView};
 use crate::series::time::{EvalGrid, TimeAxis};
 
@@ -678,7 +678,7 @@ pub struct SeriesSchema {
 /// A validated metric, time axis, and aligned fields.
 #[derive(Clone, Debug)]
 pub struct Series {
-    pub metric: MetricName,
+    pub metric: SeriesLabels,
     pub time: TimeAxis,
     pub fields: SeriesFields,
 }
@@ -686,7 +686,7 @@ impl Series {
     /// Construct after validating schema, field lengths, and strictly increasing timestamps.
     pub fn try_new(
         schema: &SeriesSchema,
-        metric: MetricName,
+        metric: SeriesLabels,
         time: TimeAxis,
         fields: SeriesFields,
     ) -> Result<Self> {
diff --git a/src/datatypes/src/series/samples/tests.rs b/src/datatypes/src/series/samples/tests.rs
index 10ed6b7693d..2548d669735 100644
--- a/src/datatypes/src/series/samples/tests.rs
+++ b/src/datatypes/src/series/samples/tests.rs
@@ -996,7 +996,7 @@ fn fields_clone_buffers_and_series_validate_schema_alignment_and_time_order() {
         ]),
         eval_grid: None,
     };
-    let metric = MetricName::try_new(None, vec![]).unwrap();
+    let metric = SeriesLabels::try_new(None, vec![]).unwrap();
     let time = TimeAxis::Explicit(ScalarBuffer::from(vec![1, 2]));
     assert!(
         Series::try_new(
@@ -1040,7 +1040,7 @@ fn float_fields_clones_and_series_keep_real_arrow_buffer_owner_alive() {
     };
     let series = Series::try_new(
         &schema,
-        MetricName::try_new(None, vec![]).unwrap(),
+        SeriesLabels::try_new(None, vec![]).unwrap(),
         TimeAxis::Explicit(ScalarBuffer::from(vec![1_i64, 2])),
         fields,
     )
@@ -1071,7 +1071,7 @@ fn series_enforces_grid_policy_and_matches_grid_spec_by_value() {
     let equal_grid = Arc::new(EvalGrid::try_new(spec).unwrap());
     let range = GridRange::try_new(equal_grid, 1, 1).unwrap();
     let fields = SeriesFields::one(Samples::from_float(Float64Array::from(vec![1.0])));
-    let metric = MetricName::try_new(None, vec![]).unwrap();
+    let metric = SeriesLabels::try_new(None, vec![]).unwrap();
     let grid_schema = SeriesSchema {
         fields: Arc::from([FieldSpec {
             name: Arc::from("value"),
@@ -1226,7 +1226,7 @@ fn short_multifield_series_uses_its_grid_range_and_checks_explicit_chunk_order()
     };
     let series = Series::try_new(
         &schema,
-        MetricName::try_new(None, vec![]).unwrap(),
+        SeriesLabels::try_new(None, vec![]).unwrap(),
         TimeAxis::Grid(GridRange::try_new(grid, 800, 20).unwrap()),
         fields.clone(),
     )
@@ -1266,7 +1266,7 @@ fn short_multifield_series_uses_its_grid_range_and_checks_explicit_chunk_order()
     assert!(
         Series::try_new(
             &explicit_schema,
-            MetricName::try_new(None, vec![]).unwrap(),
+            SeriesLabels::try_new(None, vec![]).unwrap(),
             out_of_order,
             explicit_fields,
         )
@@ -1285,7 +1285,7 @@ fn short_multifield_series_uses_its_grid_range_and_checks_explicit_chunk_order()
     assert!(
         Series::try_new(
             &explicit_schema,
-            MetricName::try_new(None, vec![]).unwrap(),
+            SeriesLabels::try_new(None, vec![]).unwrap(),
             ordered_chunks.clone(),
             ordered_fields.clone(),
         )
@@ -1299,7 +1299,7 @@ fn short_multifield_series_uses_its_grid_range_and_checks_explicit_chunk_order()
     assert!(
         Series::try_new(
             &grid_schema,
-            MetricName::try_new(None, vec![]).unwrap(),
+            SeriesLabels::try_new(None, vec![]).unwrap(),
             ordered_chunks,
             ordered_fields,
         )
@@ -1311,7 +1311,7 @@ fn short_multifield_series_uses_its_grid_range_and_checks_explicit_chunk_order()
 fn series_accepts_a_sparse_axis_on_its_schema_grid_only() {
     let spec = GridSpec::try_new(100, 10, 5).unwrap();
     let schema_grid = Arc::new(EvalGrid::try_new(spec).unwrap());
-    let metric = MetricName::try_new(None, vec![]).unwrap();
+    let metric = SeriesLabels::try_new(None, vec![]).unwrap();
     let schema = SeriesSchema {
         fields: Arc::from([FieldSpec {
             name: Arc::from("value"),
@@ -1396,7 +1396,7 @@ fn series_accepts_a_sparse_axis_on_its_schema_grid_only() {
     assert!(
         Series::try_new(
             &schema,
-            MetricName::try_new(None, vec![]).unwrap(),
+            SeriesLabels::try_new(None, vec![]).unwrap(),
             TimeAxis::GridRanges(ranges()),
             empty_fields
         )
diff --git a/src/datatypes/src/series/tests.rs b/src/datatypes/src/series/tests.rs
index 18ce6ceeecc..11875c18a8d 100644
--- a/src/datatypes/src/series/tests.rs
+++ b/src/datatypes/src/series/tests.rs
@@ -14,7 +14,7 @@
 
 use std::sync::Arc;
 
-use super::{Label, MetricName};
+use super::{Label, SeriesLabels};
 
 fn label(name: &str, value: &str) -> Label {
     Label {
@@ -25,7 +25,7 @@ fn label(name: &str, value: &str) -> Label {
 
 #[test]
 fn metric_name_sorts_labels_and_rejects_ambiguous_identity() {
-    let metric = MetricName::try_new(
+    let metric = SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![label("zone", "west"), label("host", "node-1")],
     )
@@ -34,18 +34,18 @@ fn metric_name_sorts_labels_and_rejects_ambiguous_identity() {
     assert_eq!(metric.tags()[0].name.as_ref(), "host");
     assert_eq!(metric.tags()[1].name.as_ref(), "zone");
 
-    assert!(MetricName::try_new(None, vec![label("x", "1"), label("x", "2")]).is_err());
-    assert!(MetricName::try_new(None, vec![label("__name__", "cpu")]).is_err());
+    assert!(SeriesLabels::try_new(None, vec![label("x", "1"), label("x", "2")]).is_err());
+    assert!(SeriesLabels::try_new(None, vec![label("__name__", "cpu")]).is_err());
 }
 
 #[test]
 fn metric_identity_uses_contents_and_distinguishes_absent_from_empty() {
-    let one = MetricName::try_new(
+    let one = SeriesLabels::try_new(
         Some(Arc::from(String::from("cpu"))),
         vec![label("empty", ""), label("host", "a")],
     )
     .unwrap();
-    let same = MetricName::try_new(
+    let same = SeriesLabels::try_new(
         Some(Arc::from(String::from("cpu"))),
         vec![label("host", "a"), label("empty", "")],
     )
@@ -58,7 +58,7 @@ fn metric_identity_uses_contents_and_distinguishes_absent_from_empty() {
 
 #[test]
 fn metric_name_edits_retain_shared_labels_and_labels_are_copy_on_write() {
-    let mut metric = MetricName::try_new(
+    let mut metric = SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![label("host", "a"), label("zone", "west")],
     )
@@ -89,7 +89,7 @@ fn metric_name_edits_retain_shared_labels_and_labels_are_copy_on_write() {
 
 #[test]
 fn keep_only_and_remove_all_handle_metric_name_and_ordinary_labels() {
-    let mut metric = MetricName::try_new(
+    let mut metric = SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![label("host", "a"), label("zone", "west")],
     )
diff --git a/src/datatypes/src/series/time/tests.rs b/src/datatypes/src/series/time/tests.rs
index 9e45bf38ee8..73e165f6f5f 100644
--- a/src/datatypes/src/series/time/tests.rs
+++ b/src/datatypes/src/series/time/tests.rs
@@ -643,7 +643,7 @@ mod acceptance {
     use arrow::array::Float64Array;
 
     use super::super::{EvalGrid, GridRanges, GridSpan, GridSpec, TimeAxis};
-    use crate::series::MetricName;
+    use crate::series::SeriesLabels;
     use crate::series::samples::{
         FieldSpec, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
     };
@@ -692,7 +692,7 @@ mod acceptance {
         ]));
         let series = Series::try_new(
             &schema,
-            MetricName::try_new(Some(Arc::from("m")), vec![]).unwrap(),
+            SeriesLabels::try_new(Some(Arc::from("m")), vec![]).unwrap(),
             time,
             SeriesFields::try_from_vec(vec![a, b]).unwrap(),
         )
diff --git a/src/mito-codec/src/labels.rs b/src/mito-codec/src/labels.rs
index 92e28574ffa..70df9c447c3 100644
--- a/src/mito-codec/src/labels.rs
+++ b/src/mito-codec/src/labels.rs
@@ -19,7 +19,7 @@ use api::v1::SemanticType;
 use common_telemetry::debug;
 use datatypes::data_type::ConcreteDataType;
 use datatypes::series::frame::{LabelDecodeEncoding, LabelDecodeSpec};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use datatypes::value::Value;
 use snafu::{OptionExt, ResultExt};
 use store_api::codec::PrimaryKeyEncoding;
@@ -53,7 +53,7 @@ pub enum LabelProjection {
 /// Decoded labels: either a complete metric name or a possibly partial label vector.
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub enum DecodedLabels {
-    Complete(MetricName),
+    Complete(SeriesLabels),
     Projected(Vec<Label>),
 }
 
@@ -293,7 +293,7 @@ impl PrimaryKeyLabelDecoder {
 
     /// Decodes labels without modifying or consuming `read_key`.
     ///
-    /// `All` returns a complete [`MetricName`]; `Only` returns a partial vector. Dense
+    /// `All` returns a complete [`SeriesLabels`]; `Only` returns a partial vector. Dense
     /// keys are fully checked against the exact snapshot layout even when decoding only
     /// selected fields. Sparse keys receive a full structural audit before values are read.
     pub fn decode(&mut self, read_key: &[u8]) -> Result<DecodedLabels> {
@@ -353,7 +353,7 @@ impl PrimaryKeyLabelDecoder {
         }
         if *complete {
             Ok(DecodedLabels::Complete(
-                MetricName::try_new(Some(key.metric_name.clone()), values).map_err(|error| {
+                SeriesLabels::try_new(Some(key.metric_name.clone()), values).map_err(|error| {
                     InvalidSparsePrimaryKeySnafu {
                         reason: error.to_string(),
                     }
diff --git a/src/mito2/src/engine/scan_test.rs b/src/mito2/src/engine/scan_test.rs
index be9a5f207ae..55f8cf80408 100644
--- a/src/mito2/src/engine/scan_test.rs
+++ b/src/mito2/src/engine/scan_test.rs
@@ -6245,7 +6245,7 @@ impl store_api::region_engine::RawSeriesStream for ChainedRawSeriesStream {
 fn decode_declared_labels(
     description: &datatypes::series::frame::LabelDecodeSpec,
     chunks: &[datatypes::series::raw::RawSeriesChunk],
-) -> Vec<datatypes::series::MetricName> {
+) -> Vec<datatypes::series::SeriesLabels> {
     use mito_codec::labels::{DecodedLabels, LabelProjection, PrimaryKeyLabelDecoder};
 
     let mut decoder =
diff --git a/src/promql/src/aggregate.rs b/src/promql/src/aggregate.rs
index 0ab1e26a291..6ea4d0bcb3a 100644
--- a/src/promql/src/aggregate.rs
+++ b/src/promql/src/aggregate.rs
@@ -32,7 +32,7 @@ use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
 use datatypes::arrow::array::Float64Array;
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{SampleRef, Samples, Series, SeriesSchema};
 use datatypes::series::time::{GridSpan, TimeAxis};
 
@@ -506,7 +506,7 @@ pub fn aggregate_quantile(
         .collect();
     // Members keep input order, the order Prometheus appends to its per-step heap.
     let mut group_index = HashMap::new();
-    let mut groups: Vec<(MetricName, Vec<&Series>)> = Vec::new();
+    let mut groups: Vec<(SeriesLabels, Vec<&Series>)> = Vec::new();
     for series in input {
         let metric = grouping.apply(&series.metric)?;
         let index = *group_index.entry(label_key(&metric)).or_insert_with(|| {
@@ -670,7 +670,7 @@ pub fn count_values(
 }
 
 /// Counts per point and field: one series per label set, a count of 0 being no sample.
-type Counts = Vec<(MetricName, BTreeMap<usize, Vec<f64>>)>;
+type Counts = Vec<(SeriesLabels, BTreeMap<usize, Vec<f64>>)>;
 
 fn count_series(schema: &Arc<SeriesSchema>, groups: Counts) -> Result<Vec<Series>> {
     let mut builder = GridSeriesBuilder::try_new(schema.clone())?;
@@ -729,7 +729,7 @@ impl Grouping<'_> {
     }
 
     /// Prometheus `generateGroupingLabels`; empty values are dropped as absent labels.
-    fn apply(self, input: &MetricName) -> Result<MetricName> {
+    fn apply(self, input: &SeriesLabels) -> Result<SeriesLabels> {
         let mut metric = input.clone();
         match self {
             Self::By(labels) => metric.keep_only(labels),
@@ -744,7 +744,7 @@ impl Grouping<'_> {
 
 type LabelKey = Vec<(Arc<str>, Arc<str>)>;
 
-fn metric_bytes(metric: &MetricName) -> usize {
+fn metric_bytes(metric: &SeriesLabels) -> usize {
     metric
         .name()
         .map_or(0, str::len)
@@ -761,10 +761,10 @@ fn metric_bytes(metric: &MetricName) -> usize {
                 .len()
                 .saturating_mul(std::mem::size_of::<(Arc<str>, Arc<str>)>()),
         )
-        .saturating_add(std::mem::size_of::<MetricName>())
+        .saturating_add(std::mem::size_of::<SeriesLabels>())
 }
 
-fn grouping_workspace_bytes(metric: &MetricName) -> usize {
+fn grouping_workspace_bytes(metric: &SeriesLabels) -> usize {
     metric_bytes(metric)
         .saturating_add(
             metric
@@ -843,7 +843,7 @@ fn grouping_bytes(grouping: Grouping<'_>) -> usize {
         .sum::<usize>()
 }
 
-fn label_key(metric: &MetricName) -> LabelKey {
+fn label_key(metric: &SeriesLabels) -> LabelKey {
     let mut labels = Vec::with_capacity(metric.tags().len() + 1);
     if let Some(name) = metric.name() {
         labels.push((Arc::from("__name__"), Arc::from(name)));
@@ -862,7 +862,7 @@ fn label_key(metric: &MetricName) -> LabelKey {
 const BLOCK_POINTS: usize = 64;
 
 struct Group {
-    metric: MetricName,
+    metric: SeriesLabels,
     /// Keyed by absolute grid index / `BLOCK_POINTS`; each block holds one state per field for
     /// each of its points, point by point.
     blocks: BTreeMap<usize, Box<[FloatState]>>,
diff --git a/src/promql/src/aggregate/state.rs b/src/promql/src/aggregate/state.rs
index b70d5c7fe17..a4b4b10da47 100644
--- a/src/promql/src/aggregate/state.rs
+++ b/src/promql/src/aggregate/state.rs
@@ -30,7 +30,7 @@ use std::collections::{BTreeMap, HashMap};
 use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{SampleRef, Series, SeriesSchema};
 
 use crate::aggregate::{
@@ -85,7 +85,7 @@ pub struct AccumulatorState {
 /// where no sample of that field was folded in.
 #[derive(Clone, Debug)]
 pub struct PartialGroup {
-    pub metric: MetricName,
+    pub metric: SeriesLabels,
     pub points: Vec<(usize, Vec<Option<AccumulatorState>>)>,
 }
 
diff --git a/src/promql/src/aggregate/tests.rs b/src/promql/src/aggregate/tests.rs
index 0fd86561fdd..c529033ce01 100644
--- a/src/promql/src/aggregate/tests.rs
+++ b/src/promql/src/aggregate/tests.rs
@@ -64,8 +64,8 @@ fn schema_with_grid_len(fields: &[&str], len: u64) -> Arc<SeriesSchema> {
     })
 }
 
-fn metric(name: &str, labels: &[(&str, &str)]) -> MetricName {
-    MetricName::try_new(
+fn metric(name: &str, labels: &[(&str, &str)]) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         labels
             .iter()
@@ -81,7 +81,7 @@ fn metric(name: &str, labels: &[(&str, &str)]) -> MetricName {
 /// Each field is split at a different offset into chunks with nonzero Arrow offsets.
 fn input(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     fields: &[Vec<Option<f64>>],
 ) -> Series {
@@ -423,7 +423,7 @@ fn fields_are_aggregated_independently() {
         .collect();
     let q = input(
         &schema(&["scalar"]),
-        MetricName::try_new(None, Vec::new()).unwrap(),
+        SeriesLabels::try_new(None, Vec::new()).unwrap(),
         0,
         &[q_values],
     );
@@ -878,7 +878,7 @@ fn grouping_labels_follow_prometheus_and_treat_empty_values_as_absent() {
             })
             .collect::<Vec<_>>()
     };
-    let job = MetricName::try_new(None, metric("m", &[("job", "x")]).tags().to_vec()).unwrap();
+    let job = SeriesLabels::try_new(None, metric("m", &[("job", "x")]).tags().to_vec()).unwrap();
     assert_eq!(
         labels(Grouping::By(&["host", "job"])),
         [(job.clone(), vec![Some(3.0)])]
@@ -892,13 +892,13 @@ fn grouping_labels_follow_prometheus_and_treat_empty_values_as_absent() {
     assert_eq!(by_name.len(), 2);
     assert_eq!(
         by_name[0].0,
-        MetricName::try_new(Some("a".into()), vec![]).unwrap()
+        SeriesLabels::try_new(Some("a".into()), vec![]).unwrap()
     );
     let unnamed = [
         input(&schema, metric("", &[]), 0, &[vec![Some(1.0)]]),
         input(
             &schema,
-            MetricName::try_new(None, vec![]).unwrap(),
+            SeriesLabels::try_new(None, vec![]).unwrap(),
             0,
             &[vec![Some(2.0)]],
         ),
@@ -915,7 +915,10 @@ fn grouping_labels_follow_prometheus_and_treat_empty_values_as_absent() {
     let none = labels(Grouping::By(&[]));
     assert_eq!(
         none,
-        [(MetricName::try_new(None, vec![]).unwrap(), vec![Some(3.0)])]
+        [(
+            SeriesLabels::try_new(None, vec![]).unwrap(),
+            vec![Some(3.0)]
+        )]
     );
 }
 
@@ -982,7 +985,7 @@ fn grouping_keeps_type_and_unit_labels() {
     };
     assert_eq!(
         labels(Grouping::Without(&["job"])),
-        MetricName::try_new(
+        SeriesLabels::try_new(
             None,
             metric("a", &[("__type__", "gauge"), ("__unit__", "seconds")])
                 .tags()
@@ -992,7 +995,7 @@ fn grouping_keeps_type_and_unit_labels() {
     );
     assert_eq!(
         labels(Grouping::By(&["__unit__"])),
-        MetricName::try_new(
+        SeriesLabels::try_new(
             None,
             metric("a", &[("__unit__", "seconds")]).tags().to_vec()
         )
@@ -1240,7 +1243,7 @@ fn quantile_without_q_at_a_point_has_no_result() {
     ];
     let q = input(
         &schema,
-        MetricName::try_new(None, Vec::new()).unwrap(),
+        SeriesLabels::try_new(None, Vec::new()).unwrap(),
         10,
         &[vec![Some(0.5), None, Some(0.5)]],
     );
@@ -1312,7 +1315,7 @@ fn quantile_over_one_point_members_reads_each_member_at_its_point() {
         .collect();
     let q = input(
         &schema,
-        MetricName::try_new(None, Vec::new()).unwrap(),
+        SeriesLabels::try_new(None, Vec::new()).unwrap(),
         0,
         &[vec![Some(0.5); 128]],
     );
diff --git a/src/promql/src/evaluated.rs b/src/promql/src/evaluated.rs
index 9037c418d15..473c76bf4ba 100644
--- a/src/promql/src/evaluated.rs
+++ b/src/promql/src/evaluated.rs
@@ -80,7 +80,7 @@ mod tests {
     use std::sync::Arc;
 
     use datatypes::arrow::array::Float64Array;
-    use datatypes::series::MetricName;
+    use datatypes::series::SeriesLabels;
     use datatypes::series::samples::{FieldSpec, Samples, Series, SeriesFields, SeriesSchema};
     use datatypes::series::time::{EvalGrid, GridRange, GridSpec, TimeAxis};
 
@@ -97,8 +97,8 @@ mod tests {
         }
     }
 
-    fn metric() -> MetricName {
-        MetricName::try_new(Some("requests".into()), Vec::new()).unwrap()
+    fn metric() -> SeriesLabels {
+        SeriesLabels::try_new(Some("requests".into()), Vec::new()).unwrap()
     }
 
     /// `values` are the floats this chunk finished evaluating; `start` is their absolute offset.
diff --git a/src/promql/src/extension_plan/fused_series.rs b/src/promql/src/extension_plan/fused_series.rs
index d957851902a..d0898c47e9a 100644
--- a/src/promql/src/extension_plan/fused_series.rs
+++ b/src/promql/src/extension_plan/fused_series.rs
@@ -1130,7 +1130,7 @@ fn render_labels(labels: &LabelSet) -> String {
 /// would miss exactly those collisions.
 ///
 /// The key is [`crate::grid_series::label_set`]'s normalization of the final labels rather than
-/// [`datatypes::series::MetricName`] itself: a label with an empty value is no label to
+/// [`datatypes::series::SeriesLabels`] itself: a label with an empty value is no label to
 /// Prometheus, so `{host="h", zone=""}` and `{host="h"}` are one label set and have to be compared
 /// as one. Encoding the tags as they are would file them apart and let one point hold two values.
 ///
diff --git a/src/promql/src/extension_plan/fused_series/tests.rs b/src/promql/src/extension_plan/fused_series/tests.rs
index 017f4ef6628..69ae6d533f7 100644
--- a/src/promql/src/extension_plan/fused_series/tests.rs
+++ b/src/promql/src/extension_plan/fused_series/tests.rs
@@ -64,7 +64,7 @@ use datatypes::series::frame::{RawLabelMode, pack_raw_series_chunk, raw_series_f
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, Samples, Series, SeriesFields, SeriesSchema};
 use datatypes::series::time::{EvalGrid, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 use futures::{Stream, StreamExt, TryStreamExt};
 use store_api::region_engine::RawLabelSource;
 
@@ -669,7 +669,7 @@ fn no_values(rows: &[(i64, f64)]) -> Vec<Option<f64>> {
 fn chunk_of(
     schema: &SeriesSchema,
     key: &str,
-    metric: MetricName,
+    metric: SeriesLabels,
     times: &[i64],
     values: Vec<Vec<Option<f64>>>,
     last: bool,
@@ -712,8 +712,8 @@ fn series_chunk(host: &str, rows: &[(i64, f64)], last: bool) -> RawSeriesChunk {
 }
 
 /// The metric these tests read, with `labels` on it and the name given.
-fn metric(labels: &[(&str, &str)], name: Option<&str>) -> MetricName {
-    MetricName::try_new(
+fn metric(labels: &[(&str, &str)], name: Option<&str>) -> SeriesLabels {
+    SeriesLabels::try_new(
         name.map(Arc::from),
         labels
             .iter()
@@ -1688,7 +1688,7 @@ fn a_chunk_of_several_runs_converts_its_own_rows_only() {
     .expect("the spans are increasing and inside the grid");
     let chunk = EvaluatedChunk::try_new(
         Series {
-            metric: MetricName::try_new(Some(Arc::from(METRIC)), Vec::new())
+            metric: SeriesLabels::try_new(Some(Arc::from(METRIC)), Vec::new())
                 .expect("one metric name is a legal identity"),
             time: axis,
             fields: SeriesFields::try_from_vec(vec![Samples::from_float(Float64Array::from(
@@ -2405,7 +2405,7 @@ fn a_claim_compares_label_sets_without_empty_values() {
     labels.attach(&pool);
     let axis = TimeAxis::from_grid_spans(Arc::clone(&grid()), vec![GridSpan::new(0, 5)])
         .expect("one run over the whole grid");
-    let series_of = |metric: MetricName| Series {
+    let series_of = |metric: SeriesLabels| Series {
         metric,
         time: axis.clone(),
         fields: SeriesFields::one(Samples::from_float(Float64Array::from(vec![1.0; 5]))),
diff --git a/src/promql/src/extension_plan/instant_manipulate/native.rs b/src/promql/src/extension_plan/instant_manipulate/native.rs
index ea2a28c2054..41840ee7e51 100644
--- a/src/promql/src/extension_plan/instant_manipulate/native.rs
+++ b/src/promql/src/extension_plan/instant_manipulate/native.rs
@@ -18,7 +18,7 @@ use datafusion::arrow::array::{ArrayRef, Float64Array, StringArray, TimestampMil
 use datafusion::arrow::datatypes::{DataType, SchemaRef, TimeUnit};
 use datafusion::arrow::record_batch::RecordBatch;
 use datafusion::error::{DataFusionError, Result as DataFusionResult};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::raw::RawTimestamps;
 use datatypes::series::samples::{SampleRef, Samples, SeriesFields, SeriesSchema};
 
@@ -197,7 +197,7 @@ impl NativeInstantMapping {
     /// Selects instants against typed samples, then maps only selected values to Arrow.
     pub(crate) fn evaluate(
         &self,
-        metric: &MetricName,
+        metric: &SeriesLabels,
         time: &RawTimestamps,
         fields: &SeriesFields,
     ) -> DataFusionResult<RecordBatch> {
diff --git a/src/promql/src/extension_plan/instant_manipulate/native_exec_tests.rs b/src/promql/src/extension_plan/instant_manipulate/native_exec_tests.rs
index 4250fc44ddb..c82ac1c62ef 100644
--- a/src/promql/src/extension_plan/instant_manipulate/native_exec_tests.rs
+++ b/src/promql/src/extension_plan/instant_manipulate/native_exec_tests.rs
@@ -29,7 +29,7 @@ use datafusion::logical_expr::{EmptyRelation, LogicalPlan};
 use datatypes::arrow::buffer::ScalarBuffer;
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, Samples, SeriesFields, SeriesSchema};
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 use futures::Stream;
 use store_api::region_engine::{RawLabelSource, RawSeriesStream, SendableRawSeriesStream};
 
@@ -87,7 +87,7 @@ fn chunk(time: &[i64], values: &[f64], last: bool) -> RawSeriesChunk {
     RawSeriesChunk::try_new(
         &raw_schema(),
         datatypes::arrow::buffer::Buffer::from(vec![1, 2, 3]),
-        Some(MetricName::try_new(None, vec![]).unwrap()),
+        Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         RawTimestamps::try_new(ScalarBuffer::from(time.to_vec())).unwrap(),
         SeriesFields::one(Samples::from_float(Float64Array::from(values.to_vec()))),
         last,
@@ -263,7 +263,7 @@ fn dropping_pending_stream_releases_source_chunks_and_memory() {
     let pending_chunk = RawSeriesChunk::try_new(
         &raw_schema(),
         datatypes::arrow::buffer::Buffer::from(vec![1]),
-        Some(MetricName::try_new(None, vec![]).unwrap()),
+        Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         RawTimestamps::try_new(ScalarBuffer::from(vec![10])).unwrap(),
         SeriesFields::one(samples),
         false,
@@ -344,7 +344,7 @@ fn dense_large_chunk_uses_segment_count_not_row_count_for_descriptors() {
     let dense_chunk = RawSeriesChunk::try_new(
         &raw_schema(),
         datatypes::arrow::buffer::Buffer::from(vec![1]),
-        Some(MetricName::try_new(None, vec![]).unwrap()),
+        Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         RawTimestamps::try_new(ScalarBuffer::from(timestamps)).unwrap(),
         SeriesFields::one(Samples::from_float(values)),
         true,
diff --git a/src/promql/src/extension_plan/instant_manipulate/native_tests.rs b/src/promql/src/extension_plan/instant_manipulate/native_tests.rs
index 2193d13e695..c71df401db1 100644
--- a/src/promql/src/extension_plan/instant_manipulate/native_tests.rs
+++ b/src/promql/src/extension_plan/instant_manipulate/native_tests.rs
@@ -23,7 +23,7 @@ use datafusion::logical_expr::{EmptyRelation, LogicalPlan};
 use datatypes::arrow::buffer::ScalarBuffer;
 use datatypes::series::raw::RawTimestamps;
 use datatypes::series::samples::{FieldSpec, Samples, SeriesFields, SeriesSchema};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 use super::*;
 
@@ -72,7 +72,7 @@ fn series_schema() -> Arc<SeriesSchema> {
     })
 }
 
-fn metric(zone: Option<&str>) -> MetricName {
+fn metric(zone: Option<&str>) -> SeriesLabels {
     let labels = zone
         .map(|value| {
             vec![Label {
@@ -81,7 +81,7 @@ fn metric(zone: Option<&str>) -> MetricName {
             }]
         })
         .unwrap_or_default();
-    MetricName::try_new(None, labels).unwrap()
+    SeriesLabels::try_new(None, labels).unwrap()
 }
 
 /// The ordered, deliberately non-lexical field names of the multifloat regression.
diff --git a/src/promql/src/golden.rs b/src/promql/src/golden.rs
index cab57aa3856..5a3c4b79122 100644
--- a/src/promql/src/golden.rs
+++ b/src/promql/src/golden.rs
@@ -21,7 +21,7 @@ use datatypes::series::samples::{
     FieldSpec, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 type Points = Vec<(usize, f64)>;
 
@@ -31,7 +31,7 @@ pub(crate) struct Case {
     pub(crate) schema: Arc<SeriesSchema>,
     pub(crate) series: Vec<Series>,
     pub(crate) scalar: Option<Series>,
-    pub(crate) result: Vec<(MetricName, Points)>,
+    pub(crate) result: Vec<(SeriesLabels, Points)>,
 }
 
 /// Parses a fixture of `case`/`expr`/`grid`/`series`/`scalar`/`result`/`end` blocks.
@@ -94,7 +94,7 @@ pub(crate) fn cases(text: &str) -> Vec<Case> {
     cases
 }
 
-fn parse_metric(labels: &str) -> MetricName {
+fn parse_metric(labels: &str) -> SeriesLabels {
     let mut name = None;
     let mut tags = Vec::new();
     for label in labels
@@ -111,7 +111,7 @@ fn parse_metric(labels: &str) -> MetricName {
             });
         }
     }
-    MetricName::try_new(name, tags).unwrap()
+    SeriesLabels::try_new(name, tags).unwrap()
 }
 
 fn parse_points(points: &str) -> Points {
@@ -132,7 +132,7 @@ pub(crate) fn hex(bits: &str) -> f64 {
 }
 
 /// Builds the trimmed series Eval produces: from the first to the last point, nulls between.
-fn grid_series(schema: &SeriesSchema, metric: MetricName, points: &Points) -> Option<Series> {
+fn grid_series(schema: &SeriesSchema, metric: SeriesLabels, points: &Points) -> Option<Series> {
     let (&(start, _), &(last, _)) = points.first().zip(points.last())?;
     let mut values = vec![None; last - start + 1];
     for &(index, value) in points {
@@ -329,7 +329,7 @@ pub(crate) fn close(a: f64, b: f64) -> bool {
 /// A label set as name/value pairs, the way the fixtures name one.
 type LabelKey = Vec<(String, String)>;
 
-fn label_key(metric: &MetricName) -> LabelKey {
+fn label_key(metric: &SeriesLabels) -> LabelKey {
     let mut key = metric
         .tags()
         .iter()
diff --git a/src/promql/src/grid_series.rs b/src/promql/src/grid_series.rs
index 90cfa0f2e62..532283528dd 100644
--- a/src/promql/src/grid_series.rs
+++ b/src/promql/src/grid_series.rs
@@ -21,7 +21,7 @@ use std::sync::Arc;
 use datafusion::arrow::array::builder::NullBufferBuilder;
 use datafusion::arrow::array::{Array, Float64Array, UInt32Array};
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::histogram::{HistogramBatch, HistogramBatchBuilder};
 use datatypes::series::samples::{
     DenseSamplesRef, HistogramSamples, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
@@ -312,7 +312,7 @@ impl GridSeriesBuilder {
     ///
     /// Nothing is reset: not the metric, not the index cursor, not the position order. A caller
     /// that wants a new series calls [`Self::begin_series`].
-    pub fn take_buffered(&mut self, metric: MetricName) -> Result<Option<Series>> {
+    pub fn take_buffered(&mut self, metric: SeriesLabels) -> Result<Option<Series>> {
         self.collect(metric)
     }
 
@@ -322,12 +322,12 @@ impl GridSeriesBuilder {
     /// The rows share the one buffer per field, so the result costs a span per run and not a row
     /// per position between the runs. This ends the logical series; the next one starts with
     /// [`Self::begin_series`], which is the only reset.
-    pub fn finish(&mut self, metric: MetricName) -> Result<Option<Series>> {
+    pub fn finish(&mut self, metric: SeriesLabels) -> Result<Option<Series>> {
         self.collect(metric)
     }
 
     /// Turns the buffered rows into one series over the runs they make up.
-    fn collect(&mut self, metric: MetricName) -> Result<Option<Series>> {
+    fn collect(&mut self, metric: SeriesLabels) -> Result<Option<Series>> {
         if self.indices.is_empty() {
             return Ok(None);
         }
@@ -421,7 +421,7 @@ pub(crate) fn render_label_set(labels: &LabelSet) -> String {
 }
 
 /// The label set Prometheus compares, which has no empty values.
-pub(crate) fn label_set(metric: &MetricName) -> LabelSet {
+pub(crate) fn label_set(metric: &SeriesLabels) -> LabelSet {
     let name = metric
         .name()
         .filter(|name| !name.is_empty())
diff --git a/src/promql/src/grid_series/reference.rs b/src/promql/src/grid_series/reference.rs
index fb59611ac2b..b80d89a20ee 100644
--- a/src/promql/src/grid_series/reference.rs
+++ b/src/promql/src/grid_series/reference.rs
@@ -26,7 +26,7 @@ use datatypes::series::samples::{
     HistogramSamples, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use rand::Rng;
 
 use crate::histogram_eval::float_histogram::FloatHistogram;
@@ -62,7 +62,7 @@ pub(crate) fn expand(series: &Series) -> Dense {
 }
 
 /// Asserts `actual` is the trimmed form of `expected`, with identical value bits and metric.
-pub(crate) fn assert_series_eq(actual: Option<&Series>, expected: &Dense, metric: &MetricName) {
+pub(crate) fn assert_series_eq(actual: Option<&Series>, expected: &Dense, metric: &SeriesLabels) {
     assert_series_matches(actual, expected, metric, f64::to_bits, "");
 }
 
@@ -72,7 +72,7 @@ pub(crate) fn assert_series_eq(actual: Option<&Series>, expected: &Dense, metric
 pub(crate) fn assert_series_eq_any_nan(
     actual: Option<&Series>,
     expected: &Dense,
-    metric: &MetricName,
+    metric: &SeriesLabels,
     context: &str,
 ) {
     let any_nan = |value: f64| {
@@ -88,7 +88,7 @@ pub(crate) fn assert_series_eq_any_nan(
 fn assert_series_matches(
     actual: Option<&Series>,
     expected: &Dense,
-    metric: &MetricName,
+    metric: &SeriesLabels,
     bits_of: fn(f64) -> u64,
     context: &str,
 ) {
@@ -199,7 +199,7 @@ pub(crate) fn piece_ranges(pieces: &[Series]) -> Vec<(usize, usize)> {
 /// A result carries only the positions that hold a value, so its rows may form several runs: the
 /// comparison expands it over the grid and checks it covers exactly the valued positions. `None`
 /// means no row survived, which is only right when `expected` holds no value either.
-pub(crate) fn assert_result_eq(actual: Option<&Series>, expected: &Dense, metric: &MetricName) {
+pub(crate) fn assert_result_eq(actual: Option<&Series>, expected: &Dense, metric: &SeriesLabels) {
     match actual {
         Some(actual) => assert_pieces_eq(std::slice::from_ref(actual), expected, metric),
         None => assert_pieces_eq(&[], expected, metric),
@@ -208,7 +208,7 @@ pub(crate) fn assert_result_eq(actual: Option<&Series>, expected: &Dense, metric
 
 /// Asserts `pieces` are the pieces of `expected`: they reproduce it, and together they cover
 /// exactly the positions that hold a value, none of them twice.
-pub(crate) fn assert_pieces_eq(pieces: &[Series], expected: &Dense, metric: &MetricName) {
+pub(crate) fn assert_pieces_eq(pieces: &[Series], expected: &Dense, metric: &SeriesLabels) {
     for piece in pieces {
         assert_eq!(&piece.metric, metric, "a piece changed the metric");
     }
@@ -386,10 +386,10 @@ pub(crate) fn golden_cases(text: &str) -> Vec<GoldenCase> {
     cases
 }
 
-pub(crate) fn metric_of(labels: &Labels) -> MetricName {
+pub(crate) fn metric_of(labels: &Labels) -> SeriesLabels {
     let mut labels = labels.clone();
     let name = labels.remove("__name__").map(Arc::from);
-    MetricName::try_new(
+    SeriesLabels::try_new(
         name,
         labels
             .into_iter()
@@ -402,7 +402,7 @@ pub(crate) fn metric_of(labels: &Labels) -> MetricName {
     .unwrap()
 }
 
-pub(crate) fn labels_of(metric: &MetricName) -> Labels {
+pub(crate) fn labels_of(metric: &SeriesLabels) -> Labels {
     let mut labels: Labels = metric
         .tags()
         .iter()
diff --git a/src/promql/src/grid_series/tests.rs b/src/promql/src/grid_series/tests.rs
index fbc6ebd0dc1..98c65bcb16f 100644
--- a/src/promql/src/grid_series/tests.rs
+++ b/src/promql/src/grid_series/tests.rs
@@ -22,7 +22,7 @@ use datatypes::series::samples::{
     SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
 
@@ -47,8 +47,8 @@ fn grid_schema(fields: usize, grid_len: u64) -> Arc<SeriesSchema> {
     })
 }
 
-fn metric(host: usize) -> MetricName {
-    MetricName::try_new(
+fn metric(host: usize) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![Label {
             name: Arc::from("host"),
diff --git a/src/promql/src/histogram_eval.rs b/src/promql/src/histogram_eval.rs
index 7b8668b5163..746803b5d38 100644
--- a/src/promql/src/histogram_eval.rs
+++ b/src/promql/src/histogram_eval.rs
@@ -32,7 +32,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::histogram::HistogramView;
 use datatypes::series::samples::{DenseSamplesRef, RowCursor, SampleRef, Series, SeriesSchema};
 use datatypes::series::time::{TimeAxis, union_positions};
@@ -101,7 +101,7 @@ pub fn evaluate_histograms(
     // run, as `merge_same_labelset` keeps it.
     let mut index: HashMap<LabelSet, usize> = HashMap::new();
     let mut groups: Vec<Group<'_>> = Vec::new();
-    let mut group_of = |metric: MetricName| {
+    let mut group_of = |metric: SeriesLabels| {
         *index.entry(label_set(&metric)).or_insert_with(|| {
             groups.push(Group::new(metric));
             groups.len() - 1
@@ -231,13 +231,13 @@ pub fn evaluate_histograms(
 /// The series of one label set (`le` aside): classic buckets, and the series of exactly that
 /// label set when it holds native histograms.
 struct Group<'a> {
-    metric: MetricName,
+    metric: SeriesLabels,
     classic: Vec<(f64, &'a Series)>,
     native: Option<&'a Series>,
 }
 
 impl Group<'_> {
-    fn new(metric: MetricName) -> Self {
+    fn new(metric: SeriesLabels) -> Self {
         Self {
             metric,
             classic: Vec::new(),
diff --git a/src/promql/src/histogram_eval/aggregate.rs b/src/promql/src/histogram_eval/aggregate.rs
index 0ffcca5e8e8..c2658867cb3 100644
--- a/src/promql/src/histogram_eval/aggregate.rs
+++ b/src/promql/src/histogram_eval/aggregate.rs
@@ -19,7 +19,7 @@ use std::sync::Arc;
 
 use datafusion::arrow::array::UInt32Array;
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::histogram::HistogramBatchBuilder;
 use datatypes::series::samples::{
     RowCursor, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
@@ -45,7 +45,7 @@ pub fn aggregate_histograms(
     op: HistogramAggregate,
     schema: &Arc<SeriesSchema>,
     group: &[Series],
-    metric: MetricName,
+    metric: SeriesLabels,
 ) -> Result<Option<Series>> {
     let grid = schema.eval_grid.clone().ok_or_else(|| {
         DataFusionError::Execution("histogram aggregation requires an evaluation grid".into())
diff --git a/src/promql/src/info.rs b/src/promql/src/info.rs
index 295f483a59f..b0210416e6d 100644
--- a/src/promql/src/info.rs
+++ b/src/promql/src/info.rs
@@ -29,7 +29,7 @@ use std::collections::{BTreeMap, BTreeSet, HashMap};
 use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{SampleRef, Series, SeriesSchema};
 use regex::Regex;
 
@@ -187,7 +187,7 @@ pub fn info(
 
     let width = schema.fields.len();
     let mut result_index: HashMap<LabelSet, usize> = HashMap::new();
-    let mut results: Vec<(MetricName, Vec<Row>)> = Vec::new();
+    let mut results: Vec<(SeriesLabels, Vec<Row>)> = Vec::new();
     let mut added: Vec<(Arc<str>, Arc<str>)> = Vec::new();
     let mut chosen: Vec<usize> = Vec::new();
     for series in base {
@@ -346,7 +346,7 @@ impl FirstError {
 type Signature = (Arc<str>, Vec<Option<Arc<str>>>);
 
 /// The value of each identifying label, `None` where the series does not have it.
-fn identifying_values(metric: &MetricName) -> Vec<Option<Arc<str>>> {
+fn identifying_values(metric: &SeriesLabels) -> Vec<Option<Arc<str>>> {
     IDENTIFYING_LABELS
         .iter()
         .map(|label| {
@@ -361,8 +361,8 @@ fn identifying_values(metric: &MetricName) -> Vec<Option<Arc<str>>> {
 /// Adds the data labels `info` gives a series with labels `base` to `added`; returns the name of
 /// a label another info metric already set to a different value.
 fn add_data_labels(
-    info: &MetricName,
-    base: &MetricName,
+    info: &SeriesLabels,
+    base: &SeriesLabels,
     selector: &InfoSelector,
     added: &mut Vec<(Arc<str>, Arc<str>)>,
 ) -> std::result::Result<(), Arc<str>> {
diff --git a/src/promql/src/instant_eval.rs b/src/promql/src/instant_eval.rs
index 0e76ec616a5..4828e4453dc 100644
--- a/src/promql/src/instant_eval.rs
+++ b/src/promql/src/instant_eval.rs
@@ -17,7 +17,7 @@ use std::sync::Arc;
 
 use common_query::prometheus::is_prometheus_stale_nan;
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::raw::RawTimestamps;
 use datatypes::series::samples::{SampleRef, Series, SeriesFields, SeriesSchema};
 
@@ -162,7 +162,7 @@ pub fn select_instants(
 /// ignores an offset next to `@` here, while `info()` applies it.
 pub fn timestamp_of_selection(
     schema: &Arc<SeriesSchema>,
-    metric: &MetricName,
+    metric: &SeriesLabels,
     time: &RawTimestamps,
     fields: &SeriesFields,
     indices: &[u64],
@@ -186,7 +186,7 @@ pub fn timestamp_of_selection(
 /// Takes the same selection as [`timestamp_of_selection`].
 pub fn info_sample_times(
     schema: &Arc<SeriesSchema>,
-    metric: &MetricName,
+    metric: &SeriesLabels,
     time: &RawTimestamps,
     fields: &SeriesFields,
     indices: &[u64],
@@ -254,7 +254,7 @@ pub fn timestamp_of_evaluated(
 /// have fails.
 fn project_selection(
     schema: &Arc<SeriesSchema>,
-    metric: MetricName,
+    metric: SeriesLabels,
     time: &RawTimestamps,
     fields: &SeriesFields,
     indices: &[u64],
diff --git a/src/promql/src/map.rs b/src/promql/src/map.rs
index a292234f350..d642e400bc8 100644
--- a/src/promql/src/map.rs
+++ b/src/promql/src/map.rs
@@ -35,7 +35,7 @@ use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
 use datatypes::arrow::array::Float64Array;
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{
     DenseSamplesRef, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
@@ -201,7 +201,7 @@ pub fn constant_series(schema: &SeriesSchema, range: GridRange, scalar: f64) ->
     ])));
     Series::try_new(
         schema,
-        MetricName::try_new(None, vec![]).map_err(series_error)?,
+        SeriesLabels::try_new(None, vec![]).map_err(series_error)?,
         TimeAxis::Grid(range),
         fields,
     )
@@ -232,31 +232,31 @@ fn map_float_fields(
 /// Prometheus `DropReserved(schema.IsMetadataLabel)` drops the type and unit labels with the
 /// name. Empty values are dropped too: Prometheus has no empty labels, and keeping them would
 /// hide a same-labelset collision from the caller.
-pub(crate) fn drop_metric_name(metric: &MetricName) -> Result<MetricName> {
+pub(crate) fn drop_metric_name(metric: &SeriesLabels) -> Result<SeriesLabels> {
     rebuild_labels(metric, None, |name| {
         !matches!(name, "__type__" | "__unit__")
     })
 }
 
 /// Drops labels with empty values, which Prometheus treats as absent.
-pub(crate) fn drop_empty_labels(metric: &MetricName) -> Result<MetricName> {
+pub(crate) fn drop_empty_labels(metric: &SeriesLabels) -> Result<SeriesLabels> {
     let name = metric.name().filter(|name| !name.is_empty()).map(Arc::from);
     rebuild_labels(metric, name, |_| true)
 }
 
 /// One rebuild: removing labels one by one copies the label array each time.
 fn rebuild_labels(
-    metric: &MetricName,
+    metric: &SeriesLabels,
     name: Option<Arc<str>>,
     keep: impl Fn(&str) -> bool,
-) -> Result<MetricName> {
+) -> Result<SeriesLabels> {
     let tags = metric
         .tags()
         .iter()
         .filter(|label| !label.value.is_empty() && keep(&label.name))
         .cloned()
         .collect();
-    MetricName::try_new(name, tags).map_err(series_error)
+    SeriesLabels::try_new(name, tags).map_err(series_error)
 }
 
 impl MathOp {
diff --git a/src/promql/src/map/broadcast.rs b/src/promql/src/map/broadcast.rs
index 3ddf82edba7..927e97fb9a1 100644
--- a/src/promql/src/map/broadcast.rs
+++ b/src/promql/src/map/broadcast.rs
@@ -15,7 +15,7 @@
 use std::sync::Arc;
 
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{FieldSpec, SampleRef, Series, SeriesSchema};
 use datatypes::series::time::TimeAxis;
 
@@ -226,7 +226,7 @@ fn map_grid_scalar(
     schema: &Arc<SeriesSchema>,
     vector: &Series,
     scalar: ScalarSeriesOperand<'_>,
-    metric: MetricName,
+    metric: SeriesLabels,
     calculate: impl Fn(f64, f64, f64) -> Option<f64>,
 ) -> Result<Option<Series>> {
     let vector_time = validate_float_series(schema, vector)?;
diff --git a/src/promql/src/map/tests.rs b/src/promql/src/map/tests.rs
index 66116e4d916..c40f42fcb1a 100644
--- a/src/promql/src/map/tests.rs
+++ b/src/promql/src/map/tests.rs
@@ -32,7 +32,7 @@ use datatypes::series::histogram::{
 };
 use datatypes::series::samples::{FieldSpec, HistogramSamples, SampleRef};
 use datatypes::series::time::{EvalGrid, GridRange, GridSpan, GridSpec};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 use super::*;
 use crate::functions::IeeeSqrt;
@@ -55,7 +55,7 @@ fn series(schema: &SeriesSchema, start: usize, fields: Vec<Samples>) -> Series {
     let time = TimeAxis::Grid(
         GridRange::try_new(schema.eval_grid.clone().unwrap(), start, fields[0].len()).unwrap(),
     );
-    let metric = MetricName::try_new(
+    let metric = SeriesLabels::try_new(
         Some("requests".into()),
         vec![
             Label {
@@ -604,7 +604,7 @@ fn scalar_functions_pair_scalars_by_position() {
     let scalar = |start: usize, values: &[Option<f64>]| {
         Series::try_new(
             &schema,
-            MetricName::try_new(None, Vec::new()).unwrap(),
+            SeriesLabels::try_new(None, Vec::new()).unwrap(),
             TimeAxis::Grid(
                 GridRange::try_new(schema.eval_grid.clone().unwrap(), start, values.len()).unwrap(),
             ),
diff --git a/src/promql/src/map/tests/broadcast.rs b/src/promql/src/map/tests/broadcast.rs
index 8bb4fe2c5b2..9a72ef30510 100644
--- a/src/promql/src/map/tests/broadcast.rs
+++ b/src/promql/src/map/tests/broadcast.rs
@@ -24,7 +24,7 @@ fn scalar(schema: &SeriesSchema, start: usize, samples: Samples) -> Series {
     };
     Series::try_new(
         &scalar_schema,
-        MetricName::try_new(None, vec![]).unwrap(),
+        SeriesLabels::try_new(None, vec![]).unwrap(),
         TimeAxis::Grid(
             GridRange::try_new(schema.eval_grid.clone().unwrap(), start, samples.len()).unwrap(),
         ),
@@ -559,7 +559,7 @@ fn parameters_are_read_per_point_and_missing_ones_drop_the_point() {
             .into(),
             eval_grid: schema.eval_grid.clone(),
         },
-        MetricName::try_new(None, vec![]).unwrap(),
+        SeriesLabels::try_new(None, vec![]).unwrap(),
         TimeAxis::from_grid_spans(
             schema.eval_grid.clone().unwrap(),
             vec![GridSpan::new(2, 2), GridSpan::new(5, 1)],
diff --git a/src/promql/src/map/tests/comparison.rs b/src/promql/src/map/tests/comparison.rs
index 2688474bc3f..440ac83ea5e 100644
--- a/src/promql/src/map/tests/comparison.rs
+++ b/src/promql/src/map/tests/comparison.rs
@@ -347,7 +347,7 @@ fn a_bool_comparison_keeps_the_axis_of_a_sparse_input() {
     crate::grid_series::reference::assert_result_eq(
         Some(&output),
         &expected,
-        &MetricName::try_new(
+        &SeriesLabels::try_new(
             None,
             vec![Label {
                 name: "host".into(),
diff --git a/src/promql/src/map_label.rs b/src/promql/src/map_label.rs
index 8a8a9ddc62c..33675bb931c 100644
--- a/src/promql/src/map_label.rs
+++ b/src/promql/src/map_label.rs
@@ -18,7 +18,7 @@
 use std::sync::{Arc, LazyLock};
 
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{Series, SeriesSchema};
 use regex::Regex;
 
@@ -146,7 +146,7 @@ pub fn label_join(
 }
 
 /// An empty value removes the label, as Prometheus label sets have no empty values.
-fn set_label(metric: &mut MetricName, name: &str, value: &str) -> Result<()> {
+fn set_label(metric: &mut SeriesLabels, name: &str, value: &str) -> Result<()> {
     if value.is_empty() {
         metric.remove(name);
         return Ok(());
diff --git a/src/promql/src/map_time.rs b/src/promql/src/map_time.rs
index 7177f436a1a..75175b70adb 100644
--- a/src/promql/src/map_time.rs
+++ b/src/promql/src/map_time.rs
@@ -17,7 +17,7 @@
 
 use datafusion::arrow::array::Float64Array;
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::samples::{Samples, Series, SeriesFields, SeriesSchema};
 use datatypes::series::time::{GridRange, TimeAxis};
 
@@ -96,7 +96,7 @@ fn eval_time_series(schema: &SeriesSchema, value: impl Fn(i64) -> f64) -> Result
     let fields = vec![Samples::from_float(values); schema.fields.len()];
     Series::try_new(
         schema,
-        MetricName::try_new(None, Vec::new()).map_err(external)?,
+        SeriesLabels::try_new(None, Vec::new()).map_err(external)?,
         TimeAxis::Grid(range),
         SeriesFields::try_from_vec(fields).map_err(external)?,
     )
diff --git a/src/promql/src/native/display.rs b/src/promql/src/native/display.rs
index 28099e6c50b..8765ea35942 100644
--- a/src/promql/src/native/display.rs
+++ b/src/promql/src/native/display.rs
@@ -23,7 +23,7 @@ use std::fmt::{self, Write};
 use std::sync::Arc;
 
 use datatypes::series::time::EvalGrid;
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 
 use crate::histogram_eval::HistogramFunction;
 use crate::map::MathOp;
@@ -296,7 +296,7 @@ fn binary_op(op: BinaryOp) -> &'static str {
 }
 
 /// The labels of `metric` as `name="value"` pairs, the metric name first.
-fn label_pairs(metric: &MetricName) -> String {
+fn label_pairs(metric: &SeriesLabels) -> String {
     metric
         .name()
         .map(|name| format!("__name__={name:?}"))
diff --git a/src/promql/src/native/display/tests.rs b/src/promql/src/native/display/tests.rs
index 5879d70a6df..312f9c736fb 100644
--- a/src/promql/src/native/display/tests.rs
+++ b/src/promql/src/native/display/tests.rs
@@ -16,7 +16,7 @@ use std::sync::Arc;
 
 use datatypes::series::samples::{FieldSpec, SeriesSchema};
 use datatypes::series::time::{EvalGrid, GridSpec};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 
 use super::super::plan::{
     AggregateKind, AggregateStage, BoundAggregate, BoundInput, BoundInstant, BoundMap, BoundScalar,
@@ -434,7 +434,7 @@ fn a_vector_operation_names_its_binding() {
         ),
         (
             BoundVectorOp::Absent {
-                labels: MetricName::try_new(
+                labels: SeriesLabels::try_new(
                     None,
                     vec![Label {
                         name: "job".into(),
diff --git a/src/promql/src/native/execute.rs b/src/promql/src/native/execute.rs
index 8813deff82a..9dc0985e674 100644
--- a/src/promql/src/native/execute.rs
+++ b/src/promql/src/native/execute.rs
@@ -99,7 +99,7 @@ use datatypes::series::samples::{
     DenseSamplesRef, RowCursor, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 
 use crate::aggregate;
 use crate::grid_series::{
@@ -394,7 +394,7 @@ struct NodeSpec {
 /// belongs to it and still moves forward.
 struct OpenSeries {
     /// The identity of the open series, as the chunk that opened it named it.
-    metric: MetricName,
+    metric: SeriesLabels,
     /// The last absolute position the open series decided, when it decided any.
     last_position: Option<usize>,
 }
@@ -646,7 +646,7 @@ fn label_bytes(labels: &LabelSet) -> usize {
 ///
 /// This is the convention [`label_bytes`] keeps: the payload of the shared strings and one row per
 /// label.
-fn metric_bytes(metric: &MetricName) -> usize {
+fn metric_bytes(metric: &SeriesLabels) -> usize {
     metric.name().map_or(0, |name| name.len())
         + std::mem::size_of_val(metric.tags())
         + metric
@@ -1131,7 +1131,7 @@ struct RetainedInput {
     /// set may be closed more than once -- a node that rewrites labels can make two series one --
     /// so a chunk that starts a series again is not an error, only one that starts it before the
     /// series already open ended, or names another series while it is open.
-    open: Option<(MetricName, usize)>,
+    open: Option<(SeriesLabels, usize)>,
     /// The chunks this operand handed over, in arrival order.
     series: Vec<Series>,
     /// The chunk count at which each logical series closed, exclusive, in arrival order.
@@ -1920,7 +1920,7 @@ impl BroadcastRuntime {
     ///
     /// It is what a series closes under when the operation emptied every position: the labels say
     /// which series closed, and they are the labels the operation produces, not the ones it read.
-    fn output_metric(&self, metric: &MetricName) -> Result<MetricName> {
+    fn output_metric(&self, metric: &SeriesLabels) -> Result<SeriesLabels> {
         if self.drops_labels() {
             drop_metric_name(metric)
         } else {
@@ -2083,7 +2083,7 @@ fn grid_position(grid: &EvalGrid, timestamp: i64) -> Result<usize> {
 /// A series whose selection picked no source row still closes exactly once, on a chunk that holds
 /// nothing: the labels say which series closed, and the address says it closed before its first
 /// point, as the empty chunk a window hands out for such a series does.
-fn no_row_chunk(schema: &SeriesSchema, metric: MetricName) -> Result<EvaluatedChunk> {
+fn no_row_chunk(schema: &SeriesSchema, metric: SeriesLabels) -> Result<EvaluatedChunk> {
     let grid = schema.eval_grid.clone().ok_or_else(|| {
         DataFusionError::Execution(
             "an instant selection produces an evaluated chunk, which is addressed on a grid"
@@ -4212,7 +4212,7 @@ fn map_chunk(
 /// series closed, and the axis is empty because no position holds a value. `metric` is the identity
 /// the operation produces — a map drops the name, a filtering comparison keeps it — so the caller
 /// says which, rather than this function deciding for it.
-fn no_row_series(schema: &SeriesSchema, series: &Series, metric: MetricName) -> Result<Series> {
+fn no_row_series(schema: &SeriesSchema, series: &Series, metric: SeriesLabels) -> Result<Series> {
     let grid = series.time.grid().ok_or_else(|| {
         DataFusionError::Execution("a mapped chunk must be addressed on a grid".to_string())
     })?;
diff --git a/src/promql/src/native/execute/tests.rs b/src/promql/src/native/execute/tests.rs
index 1efa3234a00..38dba5e4222 100644
--- a/src/promql/src/native/execute/tests.rs
+++ b/src/promql/src/native/execute/tests.rs
@@ -31,7 +31,7 @@ use datatypes::series::samples::{
     DenseSamplesRef, FieldSpec, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 
 use super::{
     BinaryRuntime, Emitted, NativeChunk, NativeExecutionState, NativeExecutor, NodeBuffer,
@@ -95,8 +95,8 @@ fn evaluated(grid: Arc<EvalGrid>) -> NativeType {
     NativeType::Samples(evaluated_schema(grid))
 }
 
-fn metric() -> MetricName {
-    MetricName::try_new(Some("requests".into()), Vec::new()).unwrap()
+fn metric() -> SeriesLabels {
+    SeriesLabels::try_new(Some("requests".into()), Vec::new()).unwrap()
 }
 
 /// The raw source every supported tree starts from.
@@ -270,7 +270,7 @@ fn raw_chunk(
 fn raw_chunk_of(
     schema: &SeriesSchema,
     key: &[u8],
-    metric: MetricName,
+    metric: SeriesLabels,
     timestamps: &[i64],
     values: &[f64],
     is_last: bool,
@@ -569,7 +569,7 @@ fn evaluated_chunk(
 /// evaluated result carries where it had nothing to report.
 fn evaluated_chunk_of(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     values: Vec<Option<f64>>,
     is_last: bool,
@@ -583,7 +583,7 @@ fn evaluated_chunk_of(
 /// Arrow allocation, which is what a source handing over the chunks of one batch does.
 fn evaluated_array_chunk_of(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     values: Float64Array,
     is_last: bool,
@@ -606,7 +606,7 @@ fn evaluated_array_chunk_of(
 /// same shape hold two allocations of the same size.
 fn evaluated_histogram_chunk_of(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     indices: Vec<Option<u32>>,
     table: &Arc<HistogramBatch>,
@@ -642,8 +642,8 @@ fn histogram_table_bytes(table: &Arc<HistogramBatch>) -> usize {
 }
 
 /// The series `name{job="job"}`, so two series can share the label a map leaves behind.
-fn named_metric(name: &str, job: &str) -> MetricName {
-    MetricName::try_new(
+fn named_metric(name: &str, job: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         vec![Label {
             name: "job".into(),
@@ -657,7 +657,7 @@ fn named_metric(name: &str, job: &str) -> MetricName {
 ///
 /// The two are distinct series to a scan — an empty tag value is a present label, an absent one is
 /// not — and the same label set to everything that drops empty-valued labels, as Prometheus does.
-fn host_metric(zone: Option<&str>) -> MetricName {
+fn host_metric(zone: Option<&str>) -> SeriesLabels {
     let mut tags = vec![Label {
         name: "host".into(),
         value: "web-1".into(),
@@ -668,7 +668,7 @@ fn host_metric(zone: Option<&str>) -> MetricName {
             value: zone.into(),
         });
     }
-    MetricName::try_new(Some("requests".into()), tags).unwrap()
+    SeriesLabels::try_new(Some("requests".into()), tags).unwrap()
 }
 
 fn pool() -> Arc<dyn MemoryPool> {
@@ -2126,7 +2126,7 @@ fn two_series_onto_one_label_set_after_a_window_are_rejected() {
         .push_raw(raw_chunk_of(
             &schema,
             b"series-b",
-            MetricName::try_new(
+            SeriesLabels::try_new(
                 Some("requests".into()),
                 vec![Label {
                     name: "host".into(),
@@ -2917,7 +2917,7 @@ fn two_series_with_no_result_do_not_collide() {
             .push_raw(raw_chunk_of(
                 &schema,
                 name.as_bytes(),
-                MetricName::try_new(Some(name.into()), vec![]).unwrap(),
+                SeriesLabels::try_new(Some(name.into()), vec![]).unwrap(),
                 &[0],
                 &[1.0],
                 true,
@@ -2945,7 +2945,7 @@ fn two_series_with_no_result_do_not_collide() {
 /// positions the chunk does not hold.
 fn sparse_chunk(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     spans: &[(usize, usize)],
     values: Vec<f64>,
     is_last: bool,
@@ -4207,7 +4207,7 @@ fn evaluated_input_of(count: usize, grid: Arc<EvalGrid>) -> NativeNode {
 /// One evaluated chunk of `metric` whose fields carry `columns`, one column per field.
 fn evaluated_columns(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     columns: Vec<Vec<Option<f64>>>,
     is_last: bool,
@@ -4223,7 +4223,7 @@ fn evaluated_columns(
 /// on its way in.
 fn evaluated_on(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     rows: usize,
     columns: Vec<Vec<Option<f64>>>,
@@ -4252,7 +4252,7 @@ fn evaluated_on(
 /// `len` positions from `start`.
 fn evaluated_histograms(
     schema: &SeriesSchema,
-    metric: MetricName,
+    metric: SeriesLabels,
     start: usize,
     buckets: i32,
     len: usize,
@@ -4292,8 +4292,8 @@ fn histogram_counts(chunk: &EvaluatedChunk) -> Vec<f64> {
 }
 
 /// A source bound in label mode: `name{job="api",pod="a"}` and the other series here.
-fn pod_metric(name: &str, job: &str, pod: &str) -> MetricName {
-    MetricName::try_new(
+fn pod_metric(name: &str, job: &str, pod: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         vec![
             Label {
@@ -4310,8 +4310,8 @@ fn pod_metric(name: &str, job: &str, pod: &str) -> MetricName {
 }
 
 /// The one side of a `group_left` match: `one{job=...,instance=...}`.
-fn one_metric(job: &str, instance: &str) -> MetricName {
-    MetricName::try_new(
+fn one_metric(job: &str, instance: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some("one".into()),
         vec![
             Label {
@@ -6581,8 +6581,8 @@ fn sum_grouping(group: Grouping) -> BoundAggregate {
 }
 
 /// `name{job=...,instance=...}`, the two labels these tests group by.
-fn job_instance_metric(name: &str, job: &str, instance: &str) -> MetricName {
-    MetricName::try_new(
+fn job_instance_metric(name: &str, job: &str, instance: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         vec![
             Label {
@@ -7534,7 +7534,7 @@ fn a_broadcast_refuses_two_series_that_share_a_label_set_and_releases_the_reserv
     let pool = pool();
     let mut execution = executor(&tree, Arc::clone(&pool), &ExecutionPlanMetricsSet::new());
     let first_metric =
-        MetricName::try_new(Some("requests".to_string().into()), Vec::new()).unwrap();
+        SeriesLabels::try_new(Some("requests".to_string().into()), Vec::new()).unwrap();
     execution
         .push_evaluated(evaluated_chunk_of(
             &schema,
@@ -7554,7 +7554,7 @@ fn a_broadcast_refuses_two_series_that_share_a_label_set_and_releases_the_reserv
     );
 
     let second_metric =
-        MetricName::try_new(Some("requests_total".to_string().into()), Vec::new()).unwrap();
+        SeriesLabels::try_new(Some("requests_total".to_string().into()), Vec::new()).unwrap();
     execution
         .push_evaluated(evaluated_chunk_of(
             &schema,
@@ -8172,7 +8172,7 @@ fn absent_answers_where_the_input_holds_nothing() {
     let grid = grid(0, 60_000, 3);
     let schema = evaluated_schema(Arc::clone(&grid));
     // What `absent_labels` derives from `up{job="x"}`: the name is not one of them.
-    let labels = MetricName::try_new(
+    let labels = SeriesLabels::try_new(
         None,
         vec![Label {
             name: "job".into(),
@@ -8357,7 +8357,7 @@ fn histogram_quantile_reads_the_buckets_of_the_whole_vector() {
     ))
     .unwrap();
     let bucket = |le: &str| {
-        MetricName::try_new(
+        SeriesLabels::try_new(
             Some("m".into()),
             vec![
                 Label {
@@ -8405,7 +8405,7 @@ fn histogram_quantile_reads_the_pieces_of_one_label_set_as_one_series() {
     ))
     .unwrap();
     let metric = |tags: &[(&str, &str)]| {
-        MetricName::try_new(
+        SeriesLabels::try_new(
             Some("m".into()),
             tags.iter()
                 .map(|(name, value)| Label {
diff --git a/src/promql/src/native/plan.rs b/src/promql/src/native/plan.rs
index 3e7b5fcf559..c175d5662c8 100644
--- a/src/promql/src/native/plan.rs
+++ b/src/promql/src/native/plan.rs
@@ -33,7 +33,7 @@ use std::sync::Arc;
 use datafusion::error::{DataFusionError, Result};
 use datatypes::series::samples::{FieldSpec, SeriesSchema};
 use datatypes::series::time::EvalGrid;
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 
 use crate::histogram_eval::HistogramFunction;
 use crate::map::MathOp;
@@ -278,7 +278,7 @@ pub enum BoundVectorOp {
     Sort(SortOrder),
     /// `absent`: `1` under `labels` at every point where the input holds no sample. The labels are
     /// what the compiler derives from the argument's matchers.
-    Absent { labels: MetricName },
+    Absent { labels: SeriesLabels },
     /// `histogram_quantile` or `histogram_fraction`: each classic histogram is read from the bucket
     /// series that share its labels, so this too reads the whole vector at a point.
     Histogram(HistogramFunction),
diff --git a/src/promql/src/range_eval.rs b/src/promql/src/range_eval.rs
index 02af5288cdc..6813e4d671f 100644
--- a/src/promql/src/range_eval.rs
+++ b/src/promql/src/range_eval.rs
@@ -21,7 +21,7 @@ use common_query::prometheus::is_prometheus_stale_nan;
 use datafusion::arrow::array::{Array, Float64Array};
 use datafusion::arrow::buffer::Buffer;
 use datafusion::error::{DataFusionError, Result};
-use datatypes::series::MetricName;
+use datatypes::series::SeriesLabels;
 use datatypes::series::histogram::CounterResetHint;
 use datatypes::series::raw::RawSeriesChunk;
 use datatypes::series::samples::{
@@ -275,7 +275,7 @@ fn flush_batch(
 struct SeriesState {
     /// `None` for evaluated input, which arrives as one complete series.
     primary_key: Option<Buffer>,
-    metric: MetricName,
+    metric: SeriesLabels,
     /// Largest source timestamp retained so far, or `None` while the series holds no sample: a
     /// closing chunk of a series that never produced a value carries no position to read.
     last_ts: Option<i64>,
diff --git a/src/promql/src/range_eval/tests.rs b/src/promql/src/range_eval/tests.rs
index 0c9aba0e139..4338c353c46 100644
--- a/src/promql/src/range_eval/tests.rs
+++ b/src/promql/src/range_eval/tests.rs
@@ -34,7 +34,7 @@ use datatypes::series::samples::{
     SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
 
@@ -108,8 +108,8 @@ fn grid(start_ms: i64, step_ms: i64, len: u64) -> Arc<EvalGrid> {
     Arc::new(EvalGrid::try_new(GridSpec::try_new(start_ms, step_ms, len).unwrap()).unwrap())
 }
 
-fn metric(host: u64) -> MetricName {
-    MetricName::try_new(
+fn metric(host: u64) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(Arc::from("http_requests")),
         vec![Label {
             name: Arc::from("host"),
@@ -135,7 +135,7 @@ fn per_point_probe_evaluator(
 }
 
 /// The metric of a result of `function` over the series of `metric(host)`.
-fn output_metric(function: RangeFunction, host: u64) -> MetricName {
+fn output_metric(function: RangeFunction, host: u64) -> SeriesLabels {
     let mut metric = metric(host);
     if function.drops_metric_name() {
         metric.remove("__name__");
@@ -356,7 +356,7 @@ fn fold_chunks(chunks: &[EvaluatedChunk], schema: &Arc<SeriesSchema>) -> Option<
 fn dense_series(
     rows: &[Option<Vec<Option<GridSample>>>],
     schema: Arc<SeriesSchema>,
-    metric: MetricName,
+    metric: SeriesLabels,
 ) -> Option<Series> {
     let start = rows.iter().position(Option::is_some)?;
     let end = rows.iter().rposition(Option::is_some)? + 1;
@@ -2958,7 +2958,7 @@ fn range_functions_drop_metadata_labels() {
             })
             .collect()
     };
-    let input = MetricName::try_new(
+    let input = SeriesLabels::try_new(
         Some(Arc::from("m")),
         labels(&["__type__", "__unit__", "host"]),
     )
@@ -2969,7 +2969,7 @@ fn range_functions_drop_metadata_labels() {
         anchor_ms: None,
     };
     let rows: Vec<Row> = vec![(1_000, vec![Some(1.0)]), (2_000, vec![Some(2.0)])];
-    let nameless = MetricName::try_new(None, labels(&["host"])).unwrap();
+    let nameless = SeriesLabels::try_new(None, labels(&["host"])).unwrap();
     for (function, expected) in [
         (RangeFunction::Rate, nameless.clone()),
         (RangeFunction::MadOverTime, nameless.clone()),
@@ -3356,7 +3356,7 @@ fn absent_over_time_is_absent_over_present_over_time() {
         };
         let actual = absent(&schema, &present, absent_labels(&matchers).unwrap()).unwrap();
         let (expected, labels) = expected.unwrap_or_else(|| {
-            let none = MetricName::try_new(None, Vec::new()).unwrap();
+            let none = SeriesLabels::try_new(None, Vec::new()).unwrap();
             (vec![vec![None]; grid_spec[2] as usize], none)
         });
         // `absent` over single-field inputs writes a value at every point where it is absent, so
@@ -3551,7 +3551,7 @@ fn evaluated_histograms_drop_counter_reset_hints() {
 fn empty_series(
     schema: &Arc<SeriesSchema>,
     grid: &Arc<EvalGrid>,
-    metric: MetricName,
+    metric: SeriesLabels,
     at: usize,
 ) -> Series {
     let fields = SeriesFields::try_from_vec(vec![Samples::from_float(Float64Array::from(Vec::<
diff --git a/src/promql/src/select.rs b/src/promql/src/select.rs
index 3d69f301edf..4bed5d3071b 100644
--- a/src/promql/src/select.rs
+++ b/src/promql/src/select.rs
@@ -26,7 +26,7 @@ use std::sync::Arc;
 use datafusion::error::{DataFusionError, Result};
 use datatypes::series::samples::{RowCursor, SampleRef, Series, SeriesSchema};
 use datatypes::series::time::union_positions;
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 use crate::go_sort;
 use crate::grid_series::{GridSeriesBuilder, external, owned};
@@ -258,7 +258,7 @@ pub fn limit_ratio(ratio: f64, schema: &SeriesSchema, series: &[Series]) -> Resu
 
 /// Prometheus `HashRatioSampler.SampleOffset`: the xxHash64 of the labels as `stringlabels`
 /// encodes them, each name and value prefixed by its length, over `u64::MAX`.
-fn sample_offset(metric: &MetricName) -> f64 {
+fn sample_offset(metric: &SeriesLabels) -> f64 {
     let mut data = Vec::new();
     for (name, value) in labels_with_name(metric) {
         // Prometheus label sets hold no empty value.
@@ -300,7 +300,7 @@ pub fn scalar(schema: &SeriesSchema, series: &[Series]) -> Result<Series> {
         let value = if count == 1 { value } else { Some(GO_NAN) };
         builder.push(point, &[value])?;
     }
-    let empty = MetricName::try_new(None, Vec::new()).map_err(external)?;
+    let empty = SeriesLabels::try_new(None, Vec::new()).map_err(external)?;
     // Every grid point is written above, with a value or a NaN, so the result is one run over the
     // grid and never empty. A different shape would mean this invariant broke, and returning it
     // silently would hide it.
@@ -328,7 +328,7 @@ pub fn scalar(schema: &SeriesSchema, series: &[Series]) -> Result<Series> {
 pub fn absent(
     schema: &SeriesSchema,
     series: &[Series],
-    labels: MetricName,
+    labels: SeriesLabels,
 ) -> Result<Option<Series>> {
     let points = grid_points(schema, series)?;
     let fields = schema.fields.len();
@@ -387,7 +387,7 @@ pub enum MatchOp {
 /// moving the matchers that narrow the result before those that only subtract from it; that is
 /// the order users see whenever the storage holds data, and the order used here. It changes the
 /// result only when a name has both an equality and another matcher.
-pub fn absent_labels(matchers: &[LabelMatcher]) -> Result<MetricName> {
+pub fn absent_labels(matchers: &[LabelMatcher]) -> Result<SeriesLabels> {
     let must_be_set: Vec<&str> = matchers
         .iter()
         .filter(|matcher| !matcher.matches_empty)
@@ -421,7 +421,7 @@ pub fn absent_labels(matchers: &[LabelMatcher]) -> Result<MetricName> {
         }
     }
     labels.retain(|label| !label.value.is_empty());
-    MetricName::try_new(None, labels).map_err(external)
+    SeriesLabels::try_new(None, labels).map_err(external)
 }
 
 /// Orders the series of an instant result. A range result keeps its order: Prometheus does not
@@ -544,7 +544,7 @@ fn k_param(k: f64, series: usize) -> Result<Option<usize>> {
 /// Label pairs identifying a group; empty values are absent, as in Prometheus.
 type GroupKey = Vec<(Arc<str>, Arc<str>)>;
 
-fn group_key(metric: &MetricName, grouping: &Grouping) -> GroupKey {
+fn group_key(metric: &SeriesLabels, grouping: &Grouping) -> GroupKey {
     let mut key: Vec<_> = labels_with_name(metric)
         .into_iter()
         .filter(|(name, value)| {
@@ -560,7 +560,7 @@ fn group_key(metric: &MetricName, grouping: &Grouping) -> GroupKey {
 }
 
 /// The label pairs of `metric` with `__name__` among them, sorted by name.
-fn labels_with_name(metric: &MetricName) -> Vec<(Arc<str>, Arc<str>)> {
+fn labels_with_name(metric: &SeriesLabels) -> Vec<(Arc<str>, Arc<str>)> {
     let mut labels: Vec<_> = metric
         .tags()
         .iter()
@@ -574,7 +574,7 @@ fn labels_with_name(metric: &MetricName) -> Vec<(Arc<str>, Arc<str>)> {
 }
 
 /// Prometheus `labels.Compare`: label pairs in name order, then the shorter set first.
-fn compare_labels(a: &MetricName, b: &MetricName) -> Ordering {
+fn compare_labels(a: &SeriesLabels, b: &SeriesLabels) -> Ordering {
     labels_with_name(a).cmp(&labels_with_name(b))
 }
 
diff --git a/src/promql/src/select/tests.rs b/src/promql/src/select/tests.rs
index c8d9d7e2366..b9d48816368 100644
--- a/src/promql/src/select/tests.rs
+++ b/src/promql/src/select/tests.rs
@@ -21,7 +21,7 @@ use datatypes::series::samples::{
     FieldSpec, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 use super::{
     Grouping, LabelMatcher, MatchOp, SortOrder, absent, absent_labels, limit_ratio, limitk,
@@ -50,7 +50,7 @@ fn schema(points: u64, fields: usize) -> SeriesSchema {
 }
 
 /// Parses `name=value,...`, with `__name__` as the metric name; `-` is no labels.
-fn metric(labels: &str) -> MetricName {
+fn metric(labels: &str) -> SeriesLabels {
     let mut name = None;
     let mut tags = Vec::new();
     for pair in labels.split(',').filter(|pair| *pair != "-") {
@@ -64,7 +64,7 @@ fn metric(labels: &str) -> MetricName {
             });
         }
     }
-    MetricName::try_new(name, tags).unwrap()
+    SeriesLabels::try_new(name, tags).unwrap()
 }
 
 fn dense(points: usize, values: &str) -> Dense {
@@ -81,7 +81,7 @@ fn dense(points: usize, values: &str) -> Dense {
 ///
 /// An *input*, so the holes stay nulls inside one series: the builder would cut them into pieces,
 /// and the operators under test take one series per input.
-fn build(schema: &SeriesSchema, metric: MetricName, dense: &Dense) -> Option<Series> {
+fn build(schema: &SeriesSchema, metric: SeriesLabels, dense: &Dense) -> Option<Series> {
     let start = dense
         .iter()
         .position(|row| row.iter().any(Option::is_some))?;
@@ -472,7 +472,7 @@ fn check_cases(
 }
 
 /// The fixture's label rendering: `name=value` pairs in name order, `-` when empty.
-fn render(metric: &MetricName) -> String {
+fn render(metric: &SeriesLabels) -> String {
     let mut labels: Vec<(String, String)> = metric
         .tags()
         .iter()
diff --git a/src/promql/src/source/merge/tests.rs b/src/promql/src/source/merge/tests.rs
index f7729b31ba2..ff8a8ef9ad9 100644
--- a/src/promql/src/source/merge/tests.rs
+++ b/src/promql/src/source/merge/tests.rs
@@ -35,7 +35,7 @@ use datatypes::series::frame::LabelDecodeSpec;
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, SampleRef, Samples, SeriesFields, SeriesSchema};
 use datatypes::series::time::{EvalGrid, GridSpec};
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 use futures::{Stream, StreamExt, TryStreamExt};
 use mito_codec::row_converter::{DensePrimaryKeyCodec, PrimaryKeyCodec, SortField};
 use store_api::codec::PrimaryKeyEncoding;
@@ -1663,7 +1663,7 @@ async fn ordered_input_contract_rejects_bad_key_time_and_finality_transitions()
             "explicit metric in primary-key mode",
             vec![RawSeriesChunk {
                 primary_key: a.clone(),
-                metric: Some(MetricName::try_new(None, vec![]).unwrap()),
+                metric: Some(SeriesLabels::try_new(None, vec![]).unwrap()),
                 time: RawTimestamps::try_new(ScalarBuffer::from(vec![1])).unwrap(),
                 fields: SeriesFields::one(Samples::from_float(Float64Array::from(vec![1.0]))),
                 is_last: true,
diff --git a/src/promql/src/source/tests.rs b/src/promql/src/source/tests.rs
index bf88ac382cd..10c955dd3cf 100644
--- a/src/promql/src/source/tests.rs
+++ b/src/promql/src/source/tests.rs
@@ -36,7 +36,7 @@ use datatypes::series::samples::{
     DenseSamplesRef, FieldSpec, HistogramSamples, SampleRef, Samples, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridSpec};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 use futures::{Stream, StreamExt};
 use mito_codec::row_converter::{
     DensePrimaryKeyCodec, PrimaryKeyCodec, SortField, SparsePrimaryKeyCodec,
@@ -161,7 +161,7 @@ fn schema_with_fields(names: &[&str]) -> Arc<SeriesSchema> {
     })
 }
 
-fn chunk(read_key: Buffer, metric: Option<MetricName>, final_chunk: bool) -> RawSeriesChunk {
+fn chunk(read_key: Buffer, metric: Option<SeriesLabels>, final_chunk: bool) -> RawSeriesChunk {
     let times = ScalarBuffer::from(vec![100, 200]);
     RawSeriesChunk::try_new(
         &schema(),
@@ -321,7 +321,7 @@ async fn materializes_complete_labels_without_changing_raw_chunks() {
         vec![Poll::Ready(Some(Ok(chunk(
             Buffer::from(vec![1, 2]),
             Some(
-                MetricName::try_new(
+                SeriesLabels::try_new(
                     None,
                     vec![Label {
                         name: Arc::from("x"),
@@ -339,7 +339,7 @@ async fn materializes_complete_labels_without_changing_raw_chunks() {
     assert_eq!(metric.name(), None);
     assert_eq!(metric.get("x"), Some(""));
 
-    let explicit_metric = MetricName::try_new(
+    let explicit_metric = SeriesLabels::try_new(
         Some(Arc::from("explicit_metric")),
         vec![Label {
             name: Arc::from("host"),
@@ -732,13 +732,13 @@ async fn upstream_error_and_decode_error_drop_source_terminally() {
         vec![
             Poll::Ready(Some(Ok(chunk(
                 Buffer::from(vec![3]),
-                Some(MetricName::try_new(None, vec![]).unwrap()),
+                Some(SeriesLabels::try_new(None, vec![]).unwrap()),
                 false,
             )))),
             Poll::Ready(Some(Err(upstream))),
             Poll::Ready(Some(Ok(chunk(
                 Buffer::from(vec![4]),
-                Some(MetricName::try_new(None, vec![]).unwrap()),
+                Some(SeriesLabels::try_new(None, vec![]).unwrap()),
                 true,
             )))),
         ],
@@ -857,14 +857,14 @@ async fn constructor_and_mode_errors_drop_input_without_polling_ahead() {
 
     let malformed_shape = RawSeriesChunk {
         primary_key: Buffer::from(vec![1]),
-        metric: Some(MetricName::try_new(None, vec![]).unwrap()),
+        metric: Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         time: RawTimestamps::try_new(ScalarBuffer::from(vec![100, 200])).unwrap(),
         fields: SeriesFields::one(Samples::from_float(Float64Array::from(vec![1.0]))),
         is_last: false,
     };
     let malformed_empty_time = RawSeriesChunk {
         primary_key: Buffer::from(vec![2]),
-        metric: Some(MetricName::try_new(None, vec![]).unwrap()),
+        metric: Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         time: RawTimestamps::try_new(ScalarBuffer::from(Vec::<i64>::new())).unwrap(),
         fields: SeriesFields::one(Samples::from_float(Float64Array::from(Vec::<f64>::new()))),
         is_last: false,
@@ -888,7 +888,7 @@ async fn constructor_and_mode_errors_drop_input_without_polling_ahead() {
     for (binding, metric) in [
         (
             source(PrimaryKeyEncoding::Dense),
-            Some(MetricName::try_new(None, vec![]).unwrap()),
+            Some(SeriesLabels::try_new(None, vec![]).unwrap()),
         ),
         (RawLabelSource::Explicit, None),
     ] {
diff --git a/src/promql/src/vector_match.rs b/src/promql/src/vector_match.rs
index e5e069f5485..2cdc1761b06 100644
--- a/src/promql/src/vector_match.rs
+++ b/src/promql/src/vector_match.rs
@@ -30,7 +30,7 @@ use datatypes::series::samples::{
     DenseSamplesRef, FieldSpec, RowCursor, SampleRef, Series, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRunPair, GridSpan, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 
 use crate::grid_series::{GridSample, GridSeriesBuilder, METADATA_LABELS, external, owned};
 use crate::histogram_eval::float_histogram::FloatHistogram;
@@ -306,7 +306,7 @@ const SORT_ROW_BYTES: usize =
 
 /// One row of the merge's table, charged the same way.
 const MERGE_SLOT_BYTES: usize =
-    2 * std::mem::size_of::<(GroupKey, (MetricName, Vec<(usize, usize, GridSample)>))>();
+    2 * std::mem::size_of::<(GroupKey, (SeriesLabels, Vec<(usize, usize, GridSample)>))>();
 
 /// One row of the builder's histogram table: the scalar columns and the seven list offsets.
 const HISTOGRAM_ROW_BYTES: usize = 4 * std::mem::size_of::<f64>()
@@ -462,7 +462,7 @@ fn field_metadata_bytes(
 
 /// The series of `operand` with the most labels: the widest label set one pairing of its field can
 /// build.
-fn widest_metric<'a>(operand: &'a Operand<'_>) -> Option<&'a MetricName> {
+fn widest_metric<'a>(operand: &'a Operand<'_>) -> Option<&'a SeriesLabels> {
     operand
         .series
         .iter()
@@ -482,8 +482,8 @@ fn widest_metric<'a>(operand: &'a Operand<'_>) -> Option<&'a MetricName> {
 /// it, and a pairing whose axes share no position still pays it, because the label set is built
 /// before the axes are intersected.
 fn pair_bytes(
-    many: &MetricName,
-    one: &MetricName,
+    many: &SeriesLabels,
+    one: &SeriesLabels,
     matching: &BinaryMatching,
     include: &[Arc<str>],
 ) -> usize {
@@ -516,8 +516,8 @@ fn pair_bytes(
 }
 
 /// The label text `result_metric` copies from the one side: the value of every included label it
-/// sets, and the name of a label it inserts, since `MetricName::set` copies that as well.
-fn copied_bytes(one: &MetricName, include: &[Arc<str>]) -> usize {
+/// sets, and the name of a label it inserts, since `SeriesLabels::set` copies that as well.
+fn copied_bytes(one: &SeriesLabels, include: &[Arc<str>]) -> usize {
     include
         .iter()
         .fold(0usize, |bytes, name| match one.get(name) {
@@ -530,7 +530,7 @@ fn copied_bytes(one: &MetricName, include: &[Arc<str>]) -> usize {
 
 /// The key `key_of` files a result label set under: every label with a value and the name, each
 /// charged twice for the growth of the key's `Vec`, plus the name string it copies.
-fn result_key_bytes(metric: &MetricName) -> usize {
+fn result_key_bytes(metric: &SeriesLabels) -> usize {
     metric
         .tags()
         .len()
@@ -541,7 +541,7 @@ fn result_key_bytes(metric: &MetricName) -> usize {
 
 /// The bytes one result label set keeps once a row is filed under it: the label list and the
 /// copied strings `result_metric` leaves behind, its key and its entry in the result table.
-fn result_set_bytes(metric: &MetricName, one: &MetricName, include: &[Arc<str>]) -> usize {
+fn result_set_bytes(metric: &SeriesLabels, one: &SeriesLabels, include: &[Arc<str>]) -> usize {
     metric
         .tags()
         .len()
@@ -592,7 +592,7 @@ fn merge_bytes(
 /// `group_key` copies an `on(...)` value with `Arc::from` and shares the `Arc` of an
 /// `ignoring(...)` label, so only `on(...)` adds string bytes. The pairs are charged twice because
 /// the key is collected into a `Vec` that grows by doubling.
-fn match_key_bytes(metric: &MetricName, labels: &MatchingLabels) -> usize {
+fn match_key_bytes(metric: &SeriesLabels, labels: &MatchingLabels) -> usize {
     match labels {
         MatchingLabels::On(names) => {
             names
@@ -615,7 +615,7 @@ fn match_key_bytes(metric: &MetricName, labels: &MatchingLabels) -> usize {
 
 /// The bytes `render` writes for a label set built from `metric`: each label as `name="value"`,
 /// the braces and separators between them, and the metric's name.
-fn label_text_bytes(metric: &MetricName) -> usize {
+fn label_text_bytes(metric: &SeriesLabels) -> usize {
     let named = metric
         .name()
         .map_or(0, |name| name.len().saturating_add(10));
@@ -1040,7 +1040,7 @@ impl Pairs<'_> {
     fn apply(
         &mut self,
         group: usize,
-        metric: &MetricName,
+        metric: &SeriesLabels,
         point: usize,
         many_value: SampleRef<'_>,
         one_value: SampleRef<'_>,
@@ -1101,7 +1101,7 @@ impl Pairs<'_> {
 }
 
 /// The labels Prometheus gives a fill sample: the match group of the sample it pairs with.
-fn metric_of(key: &GroupKey) -> Result<MetricName> {
+fn metric_of(key: &GroupKey) -> Result<SeriesLabels> {
     let mut name = None;
     let mut labels = Vec::with_capacity(key.len());
     for (label, value) in key {
@@ -1114,7 +1114,7 @@ fn metric_of(key: &GroupKey) -> Result<MetricName> {
             });
         }
     }
-    MetricName::try_new(name, labels).map_err(external)
+    SeriesLabels::try_new(name, labels).map_err(external)
 }
 
 fn earliest_error(errors: Vec<(usize, u8, String)>) -> Result<()> {
@@ -1250,7 +1250,7 @@ fn merge_fields(
         budget.phase(merge_bytes(merge.0, sets, width, merge.1, merge.2))?;
     }
     // Per label set: the metric and its `(point, field, value)` samples.
-    type Merged = (MetricName, Vec<(usize, usize, GridSample)>);
+    type Merged = (SeriesLabels, Vec<(usize, usize, GridSample)>);
     let mut merged: HashMap<GroupKey, Merged> = HashMap::new();
     for (field, results) in fields.into_iter().enumerate() {
         for (key, rows) in results.series {
@@ -1325,7 +1325,7 @@ fn same_grid(lhs: &SeriesSchema, rhs: &SeriesSchema) -> Result<Arc<EvalGrid>> {
 /// Prometheus.
 type GroupKey = Vec<(Arc<str>, Arc<str>)>;
 
-fn group_key(metric: &MetricName, labels: &MatchingLabels) -> GroupKey {
+fn group_key(metric: &SeriesLabels, labels: &MatchingLabels) -> GroupKey {
     let mut key: GroupKey = match labels {
         MatchingLabels::On(names) => names
             .iter()
@@ -1346,7 +1346,7 @@ fn group_key(metric: &MetricName, labels: &MatchingLabels) -> GroupKey {
     key
 }
 
-fn key_of(metric: &MetricName) -> GroupKey {
+fn key_of(metric: &SeriesLabels) -> GroupKey {
     let mut key = group_key(metric, &MatchingLabels::Ignoring(Vec::new()));
     if let Some(name) = metric.name() {
         key.insert(0, (Arc::from("__name__"), Arc::from(name)));
@@ -1424,12 +1424,12 @@ fn overlap(
 }
 
 fn result_metric(
-    many: &MetricName,
-    one: &MetricName,
+    many: &SeriesLabels,
+    one: &SeriesLabels,
     matching: &BinaryMatching,
     include: &[Arc<str>],
     drop_name: bool,
-) -> Result<MetricName> {
+) -> Result<SeriesLabels> {
     let mut metric = many.clone();
     if drop_name {
         metric.remove_all(&METADATA_LABELS);
@@ -1675,7 +1675,7 @@ struct Results {
 /// Rows in arrival order: their points, the match group each came from, and their values;
 /// `None` is a match the operator filtered.
 struct ResultRows {
-    metric: MetricName,
+    metric: SeriesLabels,
     points: Vec<usize>,
     groups: Vec<usize>,
     values: Vec<Option<GridSample>>,
@@ -1707,7 +1707,7 @@ impl Results {
     /// payload is charged here, where the value is retained, and never per grid point of a float.
     fn insert(
         &mut self,
-        metric: &MetricName,
+        metric: &SeriesLabels,
         group: usize,
         point: usize,
         value: Option<GridSample>,
diff --git a/src/promql/src/vector_match/tests.rs b/src/promql/src/vector_match/tests.rs
index ec7671c9eb6..db7fbb25963 100644
--- a/src/promql/src/vector_match/tests.rs
+++ b/src/promql/src/vector_match/tests.rs
@@ -22,7 +22,7 @@ use datatypes::series::samples::{
     FieldSpec, HistogramSamples, RowCursor, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridRange, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
 
@@ -70,10 +70,10 @@ fn schema(fields: usize, grid: &Arc<EvalGrid>) -> SeriesSchema {
     }
 }
 
-fn metric(labels: &Labels) -> MetricName {
+fn metric(labels: &Labels) -> SeriesLabels {
     let mut labels = labels.clone();
     let name = labels.remove("__name__").map(Arc::from);
-    MetricName::try_new(
+    SeriesLabels::try_new(
         name,
         labels
             .into_iter()
@@ -86,7 +86,7 @@ fn metric(labels: &Labels) -> MetricName {
     .unwrap()
 }
 
-fn labels_of(metric: &MetricName) -> Labels {
+fn labels_of(metric: &SeriesLabels) -> Labels {
     let mut labels: Labels = metric
         .tags()
         .iter()
diff --git a/src/promql/tests/native_binary.rs b/src/promql/tests/native_binary.rs
index b23bcd3b63d..14745202cf8 100644
--- a/src/promql/tests/native_binary.rs
+++ b/src/promql/tests/native_binary.rs
@@ -29,7 +29,7 @@ use datatypes::series::samples::{
     FieldSpec, SampleRef, Samples, Series, SeriesFields, SeriesSchema,
 };
 use datatypes::series::time::{EvalGrid, GridSpan, GridSpec, TimeAxis};
-use datatypes::series::{Label, MetricName, SeriesOrdering};
+use datatypes::series::{Label, SeriesLabels, SeriesOrdering};
 use promql::evaluated::EvaluatedChunk;
 use promql::map::MathOp;
 use promql::native::execute::{NativeExecutionState, NativeExecutor};
@@ -52,8 +52,8 @@ fn evaluated_schema(grid: &Arc<EvalGrid>) -> Arc<SeriesSchema> {
 }
 
 /// `name{host="h1",job="x"}`, the label set all three inputs of the tree share.
-fn metric(name: &str) -> MetricName {
-    MetricName::try_new(
+fn metric(name: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         vec![
             Label {
diff --git a/src/query/src/promql/native_compile.rs b/src/query/src/promql/native_compile.rs
index 53bb3a187a0..fd83f83b05a 100644
--- a/src/query/src/promql/native_compile.rs
+++ b/src/query/src/promql/native_compile.rs
@@ -124,7 +124,7 @@ use std::time::Duration;
 use datafusion::error::{DataFusionError, Result};
 use datatypes::series::samples::SeriesSchema;
 use datatypes::series::time::{EvalGrid, GridSpec};
-use datatypes::series::{MetricName, SeriesOrdering};
+use datatypes::series::{SeriesLabels, SeriesOrdering};
 use promql::histogram_eval::HistogramFunction;
 use promql::map::{ArithmeticOp, ComparisonOp, MathOp};
 use promql::map_time::DateFunction;
@@ -793,7 +793,7 @@ fn vector_op<'a>(
 ///
 /// `__field__`, `__schema__` and `__database__` choose what is read rather than match a label, so
 /// they are not labels of the answer, as in the existing planner.
-fn absent_labels_of(expr: &PromExpr) -> Result<MetricName> {
+fn absent_labels_of(expr: &PromExpr) -> Result<SeriesLabels> {
     let PromExpr::VectorSelector(selector) = unparen(expr) else {
         return absent_labels(&[]);
     };
diff --git a/src/query/src/promql/native_compile/tests.rs b/src/query/src/promql/native_compile/tests.rs
index d42ae4fa7b4..5ff7d75c854 100644
--- a/src/query/src/promql/native_compile/tests.rs
+++ b/src/query/src/promql/native_compile/tests.rs
@@ -23,7 +23,7 @@ use datatypes::arrow::buffer::{Buffer, ScalarBuffer};
 use datatypes::series::SeriesOrdering;
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, SampleRef, Samples, SeriesFields, SeriesSchema};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use promql::evaluated::EvaluatedChunk;
 use promql::map::MathOp;
 use promql::native::execute::{NativeExecutionState, NativeExecutor};
@@ -2379,7 +2379,7 @@ fn the_batch_acceptance_queries_compile() {
 /// `values` is one sample per timestamp, and a `None` is a position whose sample is missing rather
 /// than a value: the two are not the same thing, and a broadcast has to keep the difference.
 fn raw_x(timestamps: &[i64], values: Vec<Option<f64>>, is_last: bool) -> RawSeriesChunk {
-    let metric = MetricName::try_new(Some("x".into()), vec![]).expect("a metric name");
+    let metric = SeriesLabels::try_new(Some("x".into()), vec![]).expect("a metric name");
     RawSeriesChunk::try_new(
         &raw_schema(),
         Buffer::from_slice_ref(b"series-a"),
@@ -3746,7 +3746,7 @@ fn whole_vector_functions_bind_a_vector_operation() {
 fn agg_raw_chunk(
     schema: &SeriesSchema,
     key: &[u8],
-    metric: MetricName,
+    metric: SeriesLabels,
     timestamps: &[i64],
     values: &[f64],
 ) -> RawSeriesChunk {
@@ -3757,7 +3757,7 @@ fn agg_raw_chunk(
 fn agg_raw_chunk_with_last(
     schema: &SeriesSchema,
     key: &[u8],
-    metric: MetricName,
+    metric: SeriesLabels,
     timestamps: &[i64],
     values: &[f64],
     is_last: bool,
@@ -3774,8 +3774,8 @@ fn agg_raw_chunk_with_last(
 }
 
 /// `name` with the labels in `tags`, in the order given.
-fn agg_metric(name: &str, tags: &[(&str, &str)]) -> MetricName {
-    MetricName::try_new(
+fn agg_metric(name: &str, tags: &[(&str, &str)]) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(name.into()),
         tags.iter()
             .map(|(name, value)| Label {
diff --git a/src/store-api/src/region_engine.rs b/src/store-api/src/region_engine.rs
index 10a8c3d0011..27c2a4d6d8c 100644
--- a/src/store-api/src/region_engine.rs
+++ b/src/store-api/src/region_engine.rs
@@ -564,7 +564,7 @@ pub struct SeriesInfo {
     pub primary_key: datatypes::arrow::buffer::Buffer,
     /// Complete explicit metric name and labels, not a partial label projection; or `None` for
     /// primary-key label binding (undecoded, not nameless). The metric name itself may be absent.
-    pub metric: Option<datatypes::series::MetricName>,
+    pub metric: Option<datatypes::series::SeriesLabels>,
 }
 
 /// An immutable, finite selected set of series prepared for independent range reads.
diff --git a/src/store-api/src/region_engine/prepared_series_tests.rs b/src/store-api/src/region_engine/prepared_series_tests.rs
index d3835f5d0b1..6b485fae848 100644
--- a/src/store-api/src/region_engine/prepared_series_tests.rs
+++ b/src/store-api/src/region_engine/prepared_series_tests.rs
@@ -31,7 +31,7 @@ use datatypes::series::frame::{
 };
 use datatypes::series::raw::{RawSeriesChunk, RawTimestamps};
 use datatypes::series::samples::{FieldSpec, Samples, SeriesFields, SeriesSchema};
-use datatypes::series::{Label, MetricName};
+use datatypes::series::{Label, SeriesLabels};
 use futures::{Stream, StreamExt};
 
 use crate::codec::PrimaryKeyEncoding;
@@ -192,8 +192,8 @@ fn declared_decode_spec(source: &RawLabelSource) -> Option<LabelDecodeSpec> {
     Some(description)
 }
 
-fn metric(host: &str) -> MetricName {
-    MetricName::try_new(
+fn metric(host: &str) -> SeriesLabels {
+    SeriesLabels::try_new(
         Some(Arc::from("cpu")),
         vec![Label {
             name: Arc::from("host"),
@@ -242,7 +242,7 @@ fn schema() -> Arc<SeriesSchema> {
 
 fn chunk(
     key: &[u8],
-    metric: Option<MetricName>,
+    metric: Option<SeriesLabels>,
     timestamp: i64,
     value: f64,
     last: bool,
@@ -380,7 +380,7 @@ async fn prepared_source_label_binding_is_available_before_readers_and_matches_c
         assert_eq!(first.primary_key, Buffer::from(vec![0x10, 0x01]));
         assert_eq!(second.primary_key, Buffer::from(vec![0x10, 0x02]));
         assert_eq!(
-            first.metric.as_ref().and_then(MetricName::name),
+            first.metric.as_ref().and_then(SeriesLabels::name),
             if explicit { Some("cpu") } else { None }
         );
         assert_eq!(
diff --git a/src/table/src/table/scan/series_tests.rs b/src/table/src/table/scan/series_tests.rs
index 465cd805a79..f2120924877 100644
--- a/src/table/src/table/scan/series_tests.rs
+++ b/src/table/src/table/scan/series_tests.rs
@@ -401,7 +401,9 @@ fn chunk(schema: &SeriesSchema) -> RawSeriesChunk {
     RawSeriesChunk::try_new(
         schema,
         Buffer::from(b"complete-key".as_slice()),
-        Some(datatypes::series::MetricName::try_new(Some(Arc::from("cpu_usage")), vec![]).unwrap()),
+        Some(
+            datatypes::series::SeriesLabels::try_new(Some(Arc::from("cpu_usage")), vec![]).unwrap(),
+        ),
         RawTimestamps::try_new(vec![10, 20].into()).unwrap(),
         SeriesFields::one(Samples::from_float(Float64Array::from(vec![
             Some(1.5),

From 964aee01f23f051ebe5da471761a8916161c7ef0 Mon Sep 17 00:00:00 2001
From: discord9 <55937128+discord9@users.noreply.github.com>
Date: Fri, 23 Oct 2026 16:50:11 +0800
Subject: [PATCH 2/2] docs(datatypes): avoid overstating series matching
 identity

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>
---
 src/datatypes/src/series.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/datatypes/src/series.rs b/src/datatypes/src/series.rs
index 8feba1012dd..252b664708d 100644
--- a/src/datatypes/src/series.rs
+++ b/src/datatypes/src/series.rs
@@ -60,8 +60,7 @@ pub struct Label {
 ///
 /// The metric name is only the `__name__` value (see [`Self::name`]); this type is
 /// the whole label set a PromQL series shows. It is neither a canonical
-/// matching/grouping identity (matching drops `__name__` and compares the remaining
-/// labels canonically) nor a storage identity (read key / primary key).
+/// matching/grouping identity nor a storage identity (read key / primary key).
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct SeriesLabels {
     name: Option<Arc<str>>,