feat(metric-engine): set index options for data region (#3330)

Signed-off-by: Zhenchi <zhongzc_arch@outlook.com>

Cargo.lock

@@ -5210,6 +5210,7 @@ dependencies = [
  "common-time",
  "datafusion",
  "datatypes",
+ "itertools 0.10.5",
  "lazy_static",
  "mito2",
  "mur3",

src/metric-engine/Cargo.toml

@@ -17,6 +17,7 @@ common-telemetry.workspace = true
 common-time.workspace = true
 datafusion.workspace = true
 datatypes.workspace = true
+itertools.workspace = true
 lazy_static = "1.4"
 mito2.workspace = true
 mur3 = "0.1"

src/metric-engine/src/engine.rs

@@ -17,6 +17,7 @@ mod close;
 mod create;
 mod drop;
 mod open;
+mod options;
 mod put;
 mod read;
 mod region_metadata;

src/metric-engine/src/engine/create.rs

@@ -36,6 +36,7 @@ use store_api::region_request::{AffectedRows, RegionCreateRequest, RegionRequest
 use store_api::storage::consts::ReservedColumnId;
 use store_api::storage::RegionId;
 
+use crate::engine::options::set_index_options_for_data_region;
 use crate::engine::MetricEngineInner;
 use crate::error::{
     ConflictRegionOptionSnafu, CreateMitoRegionSnafu, InternalColumnOccupiedSnafu,
@@ -376,6 +377,9 @@ impl MetricEngineInner {
         data_region_request.primary_key =
             vec![ReservedColumnId::table_id(), ReservedColumnId::tsid()];
 
+        // set index options
+        set_index_options_for_data_region(&mut data_region_request.options);
+
         data_region_request
     }
 

src/metric-engine/src/engine/open.rs

@@ -26,6 +26,7 @@ use store_api::region_request::{AffectedRows, RegionOpenRequest, RegionRequest};
 use store_api::storage::RegionId;
 
 use super::MetricEngineInner;
+use crate::engine::options::set_index_options_for_data_region;
 use crate::error::{OpenMitoRegionSnafu, Result};
 use crate::metrics::{LOGICAL_REGION_COUNT, PHYSICAL_REGION_COUNT};
 use crate::utils;
@@ -77,9 +78,12 @@ impl MetricEngineInner {
             engine: MITO_ENGINE_NAME.to_string(),
             skip_wal_replay: request.skip_wal_replay,
         };
+
+        let mut data_region_options = request.options;
+        set_index_options_for_data_region(&mut data_region_options);
         let open_data_region_request = RegionOpenRequest {
             region_dir: data_region_dir,
-            options: request.options.clone(),
+            options: data_region_options,
             engine: MITO_ENGINE_NAME.to_string(),
             skip_wal_replay: request.skip_wal_replay,
         };

src/metric-engine/src/engine/options.rs

@@ -0,0 +1,44 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Specific options for the metric engine to create or open a region.
+
+use std::collections::HashMap;
+
+use itertools::Itertools as _;
+use store_api::storage::consts::ReservedColumnId;
+use store_api::storage::ColumnId;
+
+/// Ignore building index on the column `tsid` which is unfriendly to the inverted index and
+/// will occupy excessive space if indexed.
+const IGNORE_COLUMN_IDS_FOR_DATA_REGION: [ColumnId; 1] = [ReservedColumnId::tsid()];
+
+/// The empirical value for the seg row count of the metric data region.
+/// Compared to the mito engine, the pattern of the metric engine constructs smaller indices.
+/// Therefore, compared to the default seg row count of 1024, by adjusting it to a smaller
+/// value and appropriately increasing the size of the index, it results in an improved indexing effect.
+const SEG_ROW_COUNT_FOR_DATA_REGION: u32 = 256;
+
+/// Set the index options for the data region.
+pub fn set_index_options_for_data_region(options: &mut HashMap<String, String>) {
+    options.insert(
+        "index.inverted_index.ignore_column_ids".to_string(),
+        IGNORE_COLUMN_IDS_FOR_DATA_REGION.iter().join(","),
+    );
+
+    options.insert(
+        "index.inverted_index.segment_row_count".to_string(),
+        SEG_ROW_COUNT_FOR_DATA_REGION.to_string(),
+    );
+}