feat(inverted_index.create): add index creator (#2960)

* feat(inverted_index.create): add read/write for external intermediate files Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: MAGIC_CODEC_V1 -> CODEC_V1_MAGIC Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: polish comments Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: fix typos intermedia -> intermediate Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * fix: typos Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat(inverted_index.create): add external sorter Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: fix typos intermedia -> intermediate Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: polish comments Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: polish comments Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * refactor: drop the stream as early as possible to avoid recursive calls to poll Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * refactor: project merge sorted stream Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat: add total_row_count to SortOutput Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat: remove change of format Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat(inverted_index.create): add index creator Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: polish comments Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat: add check for total_row_count Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat: lazy set meta of writer This reverts commit 63cb5bdb5c3a08406d978357d8167ca18ed1b83b. * feat: lazyily provide inverted index writer Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * chore: polish readability Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> * feat: add push_with_name_n Signed-off-by: Zhenchi <zhongzc_arch@outlook.com> --------- Signed-off-by: Zhenchi <zhongzc_arch@outlook.com>
2025-12-22 22:20:02 +00:00 · 2023-12-20 15:02:13 +08:00
parent d2f49cbc2e
commit 7d1724f832
6 changed files with 422 additions and 32 deletions
--- a/src/index/src/inverted_index/create.rs
+++ b/src/index/src/inverted_index/create.rs
@@ -13,3 +13,45 @@
 // limitations under the License.

 mod sort;
+mod sort_create;
+
+use async_trait::async_trait;
+
+use crate::inverted_index::error::Result;
+use crate::inverted_index::format::writer::InvertedIndexWriter;
+use crate::inverted_index::BytesRef;
+
+/// `InvertedIndexCreator` provides functionality to construct an inverted index
+#[async_trait]
+pub trait InvertedIndexCreator {
+    /// Adds a value to the named index. A `None` value represents an absence of data (null)
+    ///
+    /// - `index_name`: Identifier for the index being built
+    /// - `value`: The data to be indexed, or `None` for a null entry
+    ///
+    /// It should be equivalent to calling `push_with_name_n` with `n = 1`
+    async fn push_with_name(
+        &mut self,
+        index_name: &str,
+        value: Option<BytesRef<'_>>,
+    ) -> Result<()> {
+        self.push_with_name_n(index_name, value, 1).await
+    }
+
+    /// Adds `n` identical values to the named index. `None` values represent absence of data (null)
+    ///
+    /// - `index_name`: Identifier for the index being built
+    /// - `value`: The data to be indexed, or `None` for a null entry
+    ///
+    /// It should be equivalent to calling `push_with_name` `n` times
+    async fn push_with_name_n(
+        &mut self,
+        index_name: &str,
+        value: Option<BytesRef<'_>>,
+        n: usize,
+    ) -> Result<()>;
+
+    /// Finalizes the index creation process, ensuring all data is properly indexed and stored
+    /// in the provided writer
+    async fn finish(&mut self, writer: &mut dyn InvertedIndexWriter) -> Result<()>;
+}
--- a/src/index/src/inverted_index/create/sort/external_sort.rs
+++ b/src/index/src/inverted_index/create/sort/external_sort.rs
@@ -29,6 +29,7 @@ use crate::inverted_index::create::sort::intermediate_rw::{
 };
 use crate::inverted_index::create::sort::merge_stream::MergeSortedStream;
 use crate::inverted_index::create::sort::{SortOutput, SortedStream, Sorter};
+use crate::inverted_index::create::sort_create::SorterFactory;
 use crate::inverted_index::error::Result;
 use crate::inverted_index::{Bytes, BytesRef};

@@ -137,6 +138,21 @@ impl ExternalSorter {
        }
    }

+    /// Generates a factory function that creates new `ExternalSorter` instances
+    pub fn factory(
+        temp_file_provider: Arc<dyn ExternalTempFileProvider>,
+        memory_usage_threshold: Option<usize>,
+    ) -> SorterFactory {
+        Box::new(move |index_name, segment_row_count| {
+            Box::new(Self::new(
+                index_name,
+                temp_file_provider.clone(),
+                segment_row_count,
+                memory_usage_threshold,
+            ))
+        })
+    }
+
    /// Pushes the non-null values to the values buffer and sets the bits within
    /// the specified range in the given BitVec to true.
    /// Returns the memory usage difference of the buffer after the operation.
--- a/src/index/src/inverted_index/create/sort_create.rs
+++ b/src/index/src/inverted_index/create/sort_create.rs
@@ -0,0 +1,304 @@
+// 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.
+
+use std::collections::HashMap;
+use std::num::NonZeroUsize;
+
+use async_trait::async_trait;
+use snafu::ensure;
+
+use crate::inverted_index::create::sort::{SortOutput, Sorter};
+use crate::inverted_index::create::InvertedIndexCreator;
+use crate::inverted_index::error::{InconsistentRowCountSnafu, Result};
+use crate::inverted_index::format::writer::InvertedIndexWriter;
+use crate::inverted_index::BytesRef;
+
+type IndexName = String;
+type SegmentRowCount = NonZeroUsize;
+
+/// Factory type to produce `Sorter` instances associated with an index name and segment row count
+pub type SorterFactory = Box<dyn Fn(IndexName, SegmentRowCount) -> Box<dyn Sorter> + Send>;
+
+/// `SortIndexCreator` orchestrates indexing by sorting input data for each named index
+/// and writing to an inverted index writer
+pub struct SortIndexCreator {
+    /// Factory for producing `Sorter` instances
+    sorter_factory: SorterFactory,
+
+    /// Map of index names to sorters
+    sorters: HashMap<IndexName, Box<dyn Sorter>>,
+
+    /// Number of rows in each segment, used to produce sorters
+    segment_row_count: NonZeroUsize,
+}
+
+#[async_trait]
+impl InvertedIndexCreator for SortIndexCreator {
+    /// Inserts `n` values or nulls into the sorter for the specified index.
+    ///
+    /// If the index does not exist, a new index is created even if `n` is 0.
+    /// Caller may leverage this behavior to create indexes with no data.
+    async fn push_with_name_n(
+        &mut self,
+        index_name: &str,
+        value: Option<BytesRef<'_>>,
+        n: usize,
+    ) -> Result<()> {
+        match self.sorters.get_mut(index_name) {
+            Some(sorter) => sorter.push_n(value, n).await,
+            None => {
+                let index_name = index_name.to_string();
+                let mut sorter = (self.sorter_factory)(index_name.clone(), self.segment_row_count);
+                sorter.push_n(value, n).await?;
+                self.sorters.insert(index_name, sorter);
+                Ok(())
+            }
+        }
+    }
+
+    /// Finalizes the sorting for all indexes and writes them using the inverted index writer
+    async fn finish(&mut self, writer: &mut dyn InvertedIndexWriter) -> Result<()> {
+        let mut output_row_count = None;
+        for (index_name, mut sorter) in self.sorters.drain() {
+            let SortOutput {
+                segment_null_bitmap,
+                sorted_stream,
+                total_row_count,
+            } = sorter.output().await?;
+
+            let expected_row_count = *output_row_count.get_or_insert(total_row_count);
+            ensure!(
+                expected_row_count == total_row_count,
+                InconsistentRowCountSnafu {
+                    index_name,
+                    total_row_count,
+                    expected_row_count,
+                }
+            );
+
+            writer
+                .add_index(index_name, segment_null_bitmap, sorted_stream)
+                .await?;
+        }
+
+        let total_row_count = output_row_count.unwrap_or_default() as _;
+        let segment_row_count = self.segment_row_count as _;
+        writer.finish(total_row_count, segment_row_count).await
+    }
+}
+
+impl SortIndexCreator {
+    /// Creates a new `SortIndexCreator` with the given sorter factory and index writer
+    pub fn new(sorter_factory: SorterFactory, segment_row_count: NonZeroUsize) -> Self {
+        Self {
+            sorter_factory,
+            sorters: HashMap::new(),
+            segment_row_count,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::BTreeMap;
+
+    use common_base::BitVec;
+    use futures::{stream, StreamExt};
+
+    use super::*;
+    use crate::inverted_index::create::sort::SortedStream;
+    use crate::inverted_index::error::Error;
+    use crate::inverted_index::format::writer::MockInvertedIndexWriter;
+    use crate::inverted_index::Bytes;
+
+    #[tokio::test]
+    async fn test_sort_index_creator_basic() {
+        let mut creator =
+            SortIndexCreator::new(NaiveSorter::factory(), NonZeroUsize::new(1).unwrap());
+
+        let index_values = vec![
+            ("a", vec![b"3", b"2", b"1"]),
+            ("b", vec![b"6", b"5", b"4"]),
+            ("c", vec![b"1", b"2", b"3"]),
+        ];
+
+        for (index_name, values) in index_values {
+            for value in values {
+                creator
+                    .push_with_name(index_name, Some(value))
+                    .await
+                    .unwrap();
+            }
+        }
+
+        let mut mock_writer = MockInvertedIndexWriter::new();
+        mock_writer
+            .expect_add_index()
+            .times(3)
+            .returning(|name, null_bitmap, stream| {
+                assert!(null_bitmap.is_empty());
+                match name.as_str() {
+                    "a" => assert_eq!(stream_to_values(stream), vec![b"1", b"2", b"3"]),
+                    "b" => assert_eq!(stream_to_values(stream), vec![b"4", b"5", b"6"]),
+                    "c" => assert_eq!(stream_to_values(stream), vec![b"1", b"2", b"3"]),
+                    _ => panic!("unexpected index name: {}", name),
+                }
+                Ok(())
+            });
+        mock_writer
+            .expect_finish()
+            .times(1)
+            .returning(|total_row_count, segment_row_count| {
+                assert_eq!(total_row_count, 3);
+                assert_eq!(segment_row_count.get(), 1);
+                Ok(())
+            });
+
+        creator.finish(&mut mock_writer).await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_sort_index_creator_inconsistent_row_count() {
+        let mut creator =
+            SortIndexCreator::new(NaiveSorter::factory(), NonZeroUsize::new(1).unwrap());
+
+        let index_values = vec![
+            ("a", vec![b"3", b"2", b"1"]),
+            ("b", vec![b"6", b"5", b"4"]),
+            ("c", vec![b"1", b"2"]),
+        ];
+
+        for (index_name, values) in index_values {
+            for value in values {
+                creator
+                    .push_with_name(index_name, Some(value))
+                    .await
+                    .unwrap();
+            }
+        }
+
+        let mut mock_writer = MockInvertedIndexWriter::new();
+        mock_writer
+            .expect_add_index()
+            .returning(|name, null_bitmap, stream| {
+                assert!(null_bitmap.is_empty());
+                match name.as_str() {
+                    "a" => assert_eq!(stream_to_values(stream), vec![b"1", b"2", b"3"]),
+                    "b" => assert_eq!(stream_to_values(stream), vec![b"4", b"5", b"6"]),
+                    "c" => assert_eq!(stream_to_values(stream), vec![b"1", b"2"]),
+                    _ => panic!("unexpected index name: {}", name),
+                }
+                Ok(())
+            });
+        mock_writer.expect_finish().never();
+
+        let res = creator.finish(&mut mock_writer).await;
+        assert!(matches!(res, Err(Error::InconsistentRowCount { .. })));
+    }
+
+    #[tokio::test]
+    async fn test_sort_index_creator_create_indexes_without_data() {
+        let mut creator =
+            SortIndexCreator::new(NaiveSorter::factory(), NonZeroUsize::new(1).unwrap());
+
+        creator.push_with_name_n("a", None, 0).await.unwrap();
+        creator.push_with_name_n("b", None, 0).await.unwrap();
+        creator.push_with_name_n("c", None, 0).await.unwrap();
+
+        let mut mock_writer = MockInvertedIndexWriter::new();
+        mock_writer
+            .expect_add_index()
+            .returning(|name, null_bitmap, stream| {
+                assert!(null_bitmap.is_empty());
+                assert!(matches!(name.as_str(), "a" | "b" | "c"));
+                assert!(stream_to_values(stream).is_empty());
+                Ok(())
+            });
+        mock_writer
+            .expect_finish()
+            .times(1)
+            .returning(|total_row_count, segment_row_count| {
+                assert_eq!(total_row_count, 0);
+                assert_eq!(segment_row_count.get(), 1);
+                Ok(())
+            });
+
+        creator.finish(&mut mock_writer).await.unwrap();
+    }
+
+    fn set_bit(bit_vec: &mut BitVec, index: usize) {
+        if index >= bit_vec.len() {
+            bit_vec.resize(index + 1, false);
+        }
+        bit_vec.set(index, true);
+    }
+
+    struct NaiveSorter {
+        total_row_count: usize,
+        segment_row_count: NonZeroUsize,
+        values: BTreeMap<Option<Bytes>, BitVec>,
+    }
+
+    impl NaiveSorter {
+        fn factory() -> SorterFactory {
+            Box::new(|_index_name, segment_row_count| {
+                Box::new(NaiveSorter {
+                    total_row_count: 0,
+                    segment_row_count,
+                    values: BTreeMap::new(),
+                })
+            })
+        }
+    }
+
+    #[async_trait]
+    impl Sorter for NaiveSorter {
+        async fn push(&mut self, value: Option<BytesRef<'_>>) -> Result<()> {
+            let segment_index = self.total_row_count / self.segment_row_count;
+            self.total_row_count += 1;
+
+            let bitmap = self.values.entry(value.map(Into::into)).or_default();
+            set_bit(bitmap, segment_index);
+
+            Ok(())
+        }
+
+        async fn push_n(&mut self, value: Option<BytesRef<'_>>, n: usize) -> Result<()> {
+            for _ in 0..n {
+                self.push(value).await?;
+            }
+            Ok(())
+        }
+
+        async fn output(&mut self) -> Result<SortOutput> {
+            let segment_null_bitmap = self.values.remove(&None).unwrap_or_default();
+
+            Ok(SortOutput {
+                segment_null_bitmap,
+                sorted_stream: Box::new(stream::iter(
+                    std::mem::take(&mut self.values)
+                        .into_iter()
+                        .map(|(v, b)| Ok((v.unwrap(), b))),
+                )),
+                total_row_count: self.total_row_count,
+            })
+        }
+    }
+
+    fn stream_to_values(stream: SortedStream) -> Vec<Bytes> {
+        futures::executor::block_on(async {
+            stream.map(|r| r.unwrap().0).collect::<Vec<Bytes>>().await
+        })
+    }
+}
--- a/src/index/src/inverted_index/error.rs
+++ b/src/index/src/inverted_index/error.rs
@@ -160,6 +160,13 @@ pub enum Error {

    #[snafu(display("Unknown intermediate codec magic: {magic:?}"))]
    UnknownIntermediateCodecMagic { magic: [u8; 4], location: Location },
+
+    #[snafu(display("Inconsistent row count, index_name: {index_name}, total_row_count: {total_row_count}, expected: {expected_row_count}"))]
+    InconsistentRowCount {
+        index_name: String,
+        total_row_count: usize,
+        expected_row_count: usize,
+    },
 }

 impl ErrorExt for Error {
@@ -188,6 +195,7 @@ impl ErrorExt for Error {
            | IntersectionApplierWithInList { .. }
            | EmptyPredicates { .. }
            | FstInsert { .. }
+            | InconsistentRowCount { .. }
            | IndexNotFound { .. } => StatusCode::InvalidArguments,
        }
    }
--- a/src/index/src/inverted_index/format/writer.rs
+++ b/src/index/src/inverted_index/format/writer.rs
@@ -15,6 +15,8 @@
 mod blob;
 mod single;

+use std::num::NonZeroUsize;
+
 use async_trait::async_trait;
 use common_base::BitVec;
 use futures::Stream;
@@ -23,19 +25,27 @@ use crate::inverted_index::error::Result;
 pub use crate::inverted_index::format::writer::blob::InvertedIndexBlobWriter;
 use crate::inverted_index::Bytes;

+pub type ValueStream = Box<dyn Stream<Item = Result<(Bytes, BitVec)>> + Send + Unpin>;
+
 /// Trait for writing inverted index data to underlying storage.
+#[mockall::automock]
 #[async_trait]
-pub trait InvertedIndexWriter {
+pub trait InvertedIndexWriter: Send {
    /// Adds entries to an index.
    ///
    /// * `name` is the index identifier.
    /// * `null_bitmap` marks positions of null entries.
    /// * `values` is a stream of values and their locations, yielded lexicographically.
    ///    Errors occur if the values are out of order.
-    async fn add_index<S>(&mut self, name: String, null_bitmap: BitVec, values: S) -> Result<()>
-    where
-        S: Stream<Item = Result<(Bytes, BitVec)>> + Send + Unpin;
+    async fn add_index(
+        &mut self,
+        name: String,
+        null_bitmap: BitVec,
+        values: ValueStream,
+    ) -> Result<()>;

    /// Finalizes the index writing process, ensuring all data is written.
-    async fn finish(&mut self) -> Result<()>;
+    /// `total_row_count` and `segment_row_count` is used to fill in the metadata.
+    async fn finish(&mut self, total_row_count: u64, segment_row_count: NonZeroUsize)
+        -> Result<()>;
 }
--- a/src/index/src/inverted_index/format/writer/blob.rs
+++ b/src/index/src/inverted_index/format/writer/blob.rs
@@ -12,17 +12,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.

+use std::num::NonZeroUsize;
+
 use async_trait::async_trait;
 use common_base::BitVec;
-use futures::{AsyncWrite, AsyncWriteExt, Stream};
+use futures::{AsyncWrite, AsyncWriteExt};
 use greptime_proto::v1::index::InvertedIndexMetas;
 use prost::Message;
 use snafu::ResultExt;

-use super::single::SingleIndexWriter;
 use crate::inverted_index::error::{CloseSnafu, FlushSnafu, Result, WriteSnafu};
-use crate::inverted_index::format::writer::InvertedIndexWriter;
-use crate::inverted_index::Bytes;
+use crate::inverted_index::format::writer::single::SingleIndexWriter;
+use crate::inverted_index::format::writer::{InvertedIndexWriter, ValueStream};

 /// `InvertedIndexBlobWriter`, implemented [`InvertedIndexWriter`], manages
 /// writing of an inverted index to a blob storage.
@@ -39,10 +40,12 @@ pub struct InvertedIndexBlobWriter<W> {

 #[async_trait]
 impl<W: AsyncWrite + Send + Unpin> InvertedIndexWriter for InvertedIndexBlobWriter<W> {
-    async fn add_index<S>(&mut self, name: String, null_bitmap: BitVec, values: S) -> Result<()>
-    where
-        S: Stream<Item = Result<(Bytes, BitVec)>> + Send + Unpin,
-    {
+    async fn add_index(
+        &mut self,
+        name: String,
+        null_bitmap: BitVec,
+        values: ValueStream,
+    ) -> Result<()> {
        let single_writer = SingleIndexWriter::new(
            name.clone(),
            self.written_size,
@@ -58,7 +61,14 @@ impl<W: AsyncWrite + Send + Unpin> InvertedIndexWriter for InvertedIndexBlobWrit
        Ok(())
    }

-    async fn finish(&mut self) -> Result<()> {
+    async fn finish(
+        &mut self,
+        total_row_count: u64,
+        segment_row_count: NonZeroUsize,
+    ) -> Result<()> {
+        self.metas.segment_row_count = segment_row_count.get() as _;
+        self.metas.total_row_count = total_row_count;
+
        let metas_bytes = self.metas.encode_to_vec();
        self.blob_writer
            .write_all(&metas_bytes)
@@ -78,19 +88,11 @@ impl<W: AsyncWrite + Send + Unpin> InvertedIndexWriter for InvertedIndexBlobWrit
 }

 impl<W: AsyncWrite + Send + Unpin> InvertedIndexBlobWriter<W> {
-    pub fn new(
-        blob_writer: W,
-        total_row_count: u64,
-        segment_row_count: u64,
-    ) -> InvertedIndexBlobWriter<W> {
+    pub fn new(blob_writer: W) -> InvertedIndexBlobWriter<W> {
        InvertedIndexBlobWriter {
            blob_writer,
            written_size: 0,
-            metas: InvertedIndexMetas {
-                total_row_count,
-                segment_row_count,
-                ..Default::default()
-            },
+            metas: InvertedIndexMetas::default(),
        }
    }
 }
@@ -98,9 +100,11 @@ impl<W: AsyncWrite + Send + Unpin> InvertedIndexBlobWriter<W> {
 #[cfg(test)]
 mod tests {
    use futures::io::Cursor;
+    use futures::stream;

    use super::*;
    use crate::inverted_index::format::reader::{InvertedIndexBlobReader, InvertedIndexReader};
+    use crate::inverted_index::Bytes;

    fn unpack(fst_value: u64) -> [u32; 2] {
        bytemuck::cast::<u64, [u32; 2]>(fst_value)
@@ -109,8 +113,11 @@ mod tests {
    #[tokio::test]
    async fn test_inverted_index_blob_writer_write_empty() {
        let mut blob = Vec::new();
-        let mut writer = InvertedIndexBlobWriter::new(&mut blob, 8, 1);
-        writer.finish().await.unwrap();
+        let mut writer = InvertedIndexBlobWriter::new(&mut blob);
+        writer
+            .finish(8, NonZeroUsize::new(1).unwrap())
+            .await
+            .unwrap();

        let cursor = Cursor::new(blob);
        let mut reader = InvertedIndexBlobReader::new(cursor);
@@ -123,16 +130,16 @@ mod tests {
    #[tokio::test]
    async fn test_inverted_index_blob_writer_write_basic() {
        let mut blob = Vec::new();
-        let mut writer = InvertedIndexBlobWriter::new(&mut blob, 8, 1);
+        let mut writer = InvertedIndexBlobWriter::new(&mut blob);
        writer
            .add_index(
                "tag0".to_string(),
                BitVec::from_slice(&[0b0000_0001, 0b0000_0000]),
-                futures::stream::iter(vec![
+                Box::new(stream::iter(vec![
                    Ok((Bytes::from("a"), BitVec::from_slice(&[0b0000_0001]))),
                    Ok((Bytes::from("b"), BitVec::from_slice(&[0b0010_0000]))),
                    Ok((Bytes::from("c"), BitVec::from_slice(&[0b0000_0001]))),
-                ]),
+                ])),
            )
            .await
            .unwrap();
@@ -140,15 +147,18 @@ mod tests {
            .add_index(
                "tag1".to_string(),
                BitVec::from_slice(&[0b0000_0001, 0b0000_0000]),
-                futures::stream::iter(vec![
+                Box::new(stream::iter(vec![
                    Ok((Bytes::from("x"), BitVec::from_slice(&[0b0000_0001]))),
                    Ok((Bytes::from("y"), BitVec::from_slice(&[0b0010_0000]))),
                    Ok((Bytes::from("z"), BitVec::from_slice(&[0b0000_0001]))),
-                ]),
+                ])),
            )
            .await
            .unwrap();
-        writer.finish().await.unwrap();
+        writer
+            .finish(8, NonZeroUsize::new(1).unwrap())
+            .await
+            .unwrap();

        let cursor = Cursor::new(blob);
        let mut reader = InvertedIndexBlobReader::new(cursor);