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Merge #708

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708: Reduce memory usage of the MatchingWords structure r=ManyTheFish a=loiclec

# Pull Request

## Related issue
Fixes (partially) https://github.com/meilisearch/meilisearch/issues/3115 

## What does this PR do?
1. Reduces the memory usage caused by the creation of a 10-word query tree by 20x. 
   This is done by deduplicating the `MatchingWord` values, which are heavy because of their inner DFA. The deduplication works by wrapping each `MatchingWord` in a reference-counted box and using a hash map to determine whether a  `MatchingWord` DFA already exists for a certain signature, or whether a new one needs to be built.
 
2. Avoid the worst-case scenario of creating a `MatchingWord` for extremely long words that cannot be indexed by milli.

Co-authored-by: Loïc Lecrenier <loic.lecrenier@me.com>
This commit is contained in:
bors[bot] 2022-11-30 17:47:34 +00:00 • committed by GitHub
commit 5e754b3ee0
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9 changed files with 261 additions and 86 deletions
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8
milli/src/update/index_documents/extract/extract_docid_word_positions.rs
View file

@ -7,11 +7,11 @@ use charabia::{SeparatorKind, Token, TokenKind, TokenizerBuilder};
use roaring::RoaringBitmap;
use serde_json::Value;
use super::helpers::{
concat_u32s_array, create_sorter, sorter_into_reader, GrenadParameters, MAX_WORD_LENGTH,
};
use super::helpers::{concat_u32s_array, create_sorter, sorter_into_reader, GrenadParameters};
use crate::error::{InternalError, SerializationError};
use crate::{absolute_from_relative_position, FieldId, Result, MAX_POSITION_PER_ATTRIBUTE};
use crate::{
absolute_from_relative_position, FieldId, Result, MAX_POSITION_PER_ATTRIBUTE, MAX_WORD_LENGTH,
};
/// Extracts the word and positions where this word appear and
/// prefixes it by the document id.

3
milli/src/update/index_documents/extract/extract_facet_string_docids.rs
View file

@ -6,9 +6,8 @@ use heed::BytesEncode;
use super::helpers::{create_sorter, sorter_into_reader, try_split_array_at, GrenadParameters};
use crate::heed_codec::facet::{FacetGroupKey, FacetGroupKeyCodec};
use crate::heed_codec::StrRefCodec;
use crate::update::index_documents::helpers::MAX_FACET_VALUE_LENGTH;
use crate::update::index_documents::merge_cbo_roaring_bitmaps;
use crate::{FieldId, Result};
use crate::{FieldId, Result, MAX_FACET_VALUE_LENGTH};
/// Extracts the facet string and the documents ids where this facet string appear.
///

3
milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
View file

@ -12,9 +12,8 @@ use serde_json::Value;
use super::helpers::{create_sorter, keep_first, sorter_into_reader, GrenadParameters};
use crate::error::InternalError;
use crate::facet::value_encoding::f64_into_bytes;
use crate::update::index_documents::helpers::MAX_FACET_VALUE_LENGTH;
use crate::update::index_documents::{create_writer, writer_into_reader};
use crate::{CboRoaringBitmapCodec, DocumentId, FieldId, Result, BEU32};
use crate::{CboRoaringBitmapCodec, DocumentId, FieldId, Result, BEU32, MAX_FACET_VALUE_LENGTH};
/// Extracts the facet values of each faceted field of each document.
///

15
milli/src/update/index_documents/helpers/mod.rs
View file

@ -18,20 +18,7 @@ pub use merge_functions::{
serialize_roaring_bitmap, MergeFn,
};
/// The maximum length a LMDB key can be.
///
/// Note that the actual allowed length is a little bit higher, but
/// we keep a margin of safety.
const MAX_LMDB_KEY_LENGTH: usize = 500;
/// The maximum length a field value can be when inserted in an LMDB key.
///
/// This number is determined by the keys of the different facet databases
/// and adding a margin of safety.
pub const MAX_FACET_VALUE_LENGTH: usize = MAX_LMDB_KEY_LENGTH - 20;
/// The maximum length a word can be
pub const MAX_WORD_LENGTH: usize = MAX_LMDB_KEY_LENGTH / 2;
use crate::MAX_WORD_LENGTH;
pub fn valid_lmdb_key(key: impl AsRef<[u8]>) -> bool {
key.as_ref().len() <= MAX_WORD_LENGTH * 2 && !key.as_ref().is_empty()