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Introduce a database to store docids in groups of four positions

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This commit is contained in:
Clément Renault 2020-08-29 16:29:18 +02:00
parent 3db517548d
commit ad5cafbfed
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GPG Key ID: 92ADA4E935E71FA4
2 changed files with 72 additions and 26 deletions
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95
src/bin/indexer.rs
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@ -31,11 +31,12 @@ const MAX_ATTRIBUTES: usize = u32::max_value() as usize / MAX_POSITION;
const HEADERS_KEY: &[u8] = b"\0headers";
const DOCUMENTS_IDS_KEY: &[u8] = b"\x04documents-ids";
const WORDS_FST_KEY: &[u8] = b"\x05words-fst";
const WORD_POSITIONS_BYTE: u8 = 1;
const WORD_POSITION_DOCIDS_BYTE: u8 = 2;
const WORD_ATTRIBUTE_DOCIDS_BYTE: u8 = 3;
const WORDS_FST_KEY: &[u8] = b"\x06words-fst";
const DOCUMENTS_IDS_BYTE: u8 = 4;
const WORD_ATTRIBUTE_DOCIDS_BYTE: u8 = 3;
const WORD_FOUR_POSITIONS_DOCIDS_BYTE: u8 = 5;
const WORD_POSITION_DOCIDS_BYTE: u8 = 2;
const WORD_POSITIONS_BYTE: u8 = 1;
#[cfg(target_os = "linux")]
#[global_allocator]
@ -87,8 +88,8 @@ struct IndexerOpt {
max_memory: Option<usize>,
/// Size of the ARC cache when indexing.
#[structopt(long)]
arc_cache_size: Option<usize>,
#[structopt(long, default_value = "65535")]
arc_cache_size: usize,
/// The name of the compression algorithm to use when compressing intermediate
/// chunks during indexing documents.
@ -122,6 +123,7 @@ type MergeFn = fn(&[u8], &[Vec<u8>]) -> Result<Vec<u8>, ()>;
struct Store {
word_positions: ArcCache<SmallVec32<u8>, RoaringBitmap>,
word_position_docids: ArcCache<(SmallVec32<u8>, Position), RoaringBitmap>,
word_four_positions_docids: ArcCache<(SmallVec32<u8>, Position), RoaringBitmap>,
word_attribute_docids: ArcCache<(SmallVec32<u8>, Attribute), RoaringBitmap>,
documents_ids: RoaringBitmap,
sorter: Sorter<MergeFn>,
@ -130,7 +132,7 @@ struct Store {
impl Store {
fn new(
arc_cache_size: Option<usize>,
arc_cache_size: usize,
max_nb_chunks: Option<usize>,
max_memory: Option<usize>,
chunk_compression_type: CompressionType,
@ -155,11 +157,10 @@ impl Store {
builder.chunk_compression_level(level);
}
let arc_cache_size = arc_cache_size.unwrap_or(65_535);
Store {
word_positions: ArcCache::new(arc_cache_size),
word_position_docids: ArcCache::new(arc_cache_size),
word_four_positions_docids: ArcCache::new(arc_cache_size),
word_attribute_docids: ArcCache::new(arc_cache_size),
documents_ids: RoaringBitmap::new(),
sorter: builder.build(),
@ -167,21 +168,32 @@ impl Store {
}
}
// Save the positions where this word has been seen.
pub fn insert_word_position(&mut self, word: &str, position: Position) -> anyhow::Result<()> {
let word = SmallVec32::from(word.as_bytes());
let position = RoaringBitmap::from_iter(Some(position));
let (_, lrus) = self.word_positions.insert(word, position, |old, new| old.union_with(&new));
Self::write_word_positions(&mut self.sorter, lrus)
}
// Save the documents ids under the position and word we have seen it.
pub fn insert_word_position_docid(&mut self, word: &str, position: Position, id: DocumentId) -> anyhow::Result<()> {
let word_vec = SmallVec32::from(word.as_bytes());
let ids = RoaringBitmap::from_iter(Some(id));
let (_, lrus) = self.word_position_docids.insert((word_vec, position), ids, |old, new| old.union_with(&new));
Self::write_word_position_docids(&mut self.sorter, lrus)?;
self.insert_word_attribute_docid(word, position / MAX_POSITION as u32, id)
self.insert_word_position(word, position)?;
self.insert_word_four_positions_docid(word, position, id)?;
self.insert_word_attribute_docid(word, position / MAX_POSITION as u32, id)?;
Ok(())
}
pub fn insert_word_four_positions_docid(&mut self, word: &str, position: Position, id: DocumentId) -> anyhow::Result<()> {
let position = position - position % 4;
let word_vec = SmallVec32::from(word.as_bytes());
let ids = RoaringBitmap::from_iter(Some(id));
let (_, lrus) = self.word_position_docids.insert((word_vec, position), ids, |old, new| old.union_with(&new));
Self::write_word_four_positions_docids(&mut self.sorter, lrus)
}
// Save the positions where this word has been seen.
pub fn insert_word_position(&mut self, word: &str, position: Position) -> anyhow::Result<()> {
let word = SmallVec32::from(word.as_bytes());
let position = RoaringBitmap::from_iter(Some(position));
let (_, lrus) = self.word_positions.insert(word, position, |old, new| old.union_with(&new));
Self::write_word_positions(&mut self.sorter, lrus)
}
// Save the documents ids under the attribute and word we have seen it.
@ -196,11 +208,8 @@ impl Store {
Ok(self.sorter.insert(HEADERS_KEY, headers)?)
}
pub fn write_document_id(&mut self, id: DocumentId) {
self.documents_ids.insert(id);
}
pub fn write_document(&mut self, id: DocumentId, content: &[u8]) -> anyhow::Result<()> {
self.documents_ids.insert(id);
Ok(self.documents_sorter.insert(id.to_be_bytes(), content)?)
}
@ -252,6 +261,31 @@ impl Store {
Ok(())
}
fn write_word_four_positions_docids<I>(sorter: &mut Sorter<MergeFn>, iter: I) -> anyhow::Result<()>
where I: IntoIterator<Item=((SmallVec32<u8>, Position), RoaringBitmap)>
{
// postings positions ids keys are all prefixed
let mut key = vec![WORD_FOUR_POSITIONS_DOCIDS_BYTE];
let mut buffer = Vec::new();
for ((word, pos), ids) in iter {
key.truncate(1);
key.extend_from_slice(&word);
// we postfix the word by the positions it appears in
key.extend_from_slice(&pos.to_be_bytes());
// We serialize the document ids into a buffer
buffer.clear();
buffer.reserve(ids.serialized_size());
ids.serialize_into(&mut buffer)?;
// that we write under the generated key into MTBL
if lmdb_key_valid_size(&key) {
sorter.insert(&key, &buffer)?;
}
}
Ok(())
}
fn write_word_attribute_docids<I>(sorter: &mut Sorter<MergeFn>, iter: I) -> anyhow::Result<()>
where I: IntoIterator<Item=((SmallVec32<u8>, Attribute), RoaringBitmap)>
{
@ -287,6 +321,7 @@ impl Store {
pub fn finish(mut self) -> anyhow::Result<(Reader<Mmap>, Reader<Mmap>)> {
Self::write_word_positions(&mut self.sorter, self.word_positions)?;
Self::write_word_position_docids(&mut self.sorter, self.word_position_docids)?;
Self::write_word_four_positions_docids(&mut self.sorter, self.word_four_positions_docids)?;
Self::write_word_attribute_docids(&mut self.sorter, self.word_attribute_docids)?;
Self::write_documents_ids(&mut self.sorter, self.documents_ids)?;
@ -346,7 +381,12 @@ fn merge(key: &[u8], values: &[Vec<u8>]) -> Result<Vec<u8>, ()> {
Ok(values[0].to_vec())
},
key => match key[0] {
DOCUMENTS_IDS_BYTE | WORD_POSITIONS_BYTE | WORD_POSITION_DOCIDS_BYTE | WORD_ATTRIBUTE_DOCIDS_BYTE => {
DOCUMENTS_IDS_BYTE
| WORD_POSITIONS_BYTE
| WORD_POSITION_DOCIDS_BYTE
| WORD_FOUR_POSITIONS_DOCIDS_BYTE
| WORD_ATTRIBUTE_DOCIDS_BYTE =>
{
let mut first = RoaringBitmap::deserialize_from(values[0].as_slice()).unwrap();
for value in &values[1..] {
@ -388,6 +428,11 @@ fn lmdb_writer(wtxn: &mut heed::RwTxn, index: &Index, key: &[u8], val: &[u8]) ->
index.word_position_docids.as_polymorph()
.put::<_, ByteSlice, ByteSlice>(wtxn, &key[1..], val)?;
}
else if key.starts_with(&[WORD_FOUR_POSITIONS_DOCIDS_BYTE]) {
// Write the postings lists
index.word_four_positions_docids.as_polymorph()
.put::<_, ByteSlice, ByteSlice>(wtxn, &key[1..], val)?;
}
else if key.starts_with(&[WORD_ATTRIBUTE_DOCIDS_BYTE]) {
// Write the attribute postings lists
index.word_attribute_docids.as_polymorph()
@ -421,7 +466,7 @@ fn index_csv(
mut rdr: csv::Reader<Box<dyn Read + Send>>,
thread_index: usize,
num_threads: usize,
arc_cache_size: Option<usize>,
arc_cache_size: usize,
max_nb_chunks: Option<usize>,
max_memory: Option<usize>,
chunk_compression_type: CompressionType,
@ -463,7 +508,6 @@ fn index_csv(
for (pos, word) in lexer::break_string(&content).enumerate().take(MAX_POSITION) {
let word = word.cow_to_lowercase();
let position = (attr * MAX_POSITION + pos) as u32;
store.insert_word_position(&word, position)?;
store.insert_word_position_docid(&word, position, document_id)?;
}
}
@ -473,7 +517,6 @@ fn index_csv(
writer.write_byte_record(document.as_byte_record())?;
let document = writer.into_inner()?;
store.write_document(document_id, &document)?;
store.write_document_id(document_id);
}
// Compute the document id of the the next document.

3
src/lib.rs
View File

@ -39,6 +39,8 @@ pub struct Index {
pub word_positions: Database<Str, RoaringBitmapCodec>,
/// Maps a word at a position (u32) and all the documents ids where the given word appears.
pub word_position_docids: Database<StrBEU32Codec, RoaringBitmapCodec>,
/// Maps a word and a range of 4 positions, i.e. 0..4, 4..8, 12..16.
pub word_four_positions_docids: Database<StrBEU32Codec, RoaringBitmapCodec>,
/// Maps a word and an attribute (u32) to all the documents ids where the given word appears.
pub word_attribute_docids: Database<StrBEU32Codec, RoaringBitmapCodec>,
/// Maps the document id to the document as a CSV line.
@ -51,6 +53,7 @@ impl Index {
main: env.create_poly_database(None)?,
word_positions: env.create_database(Some("word-positions"))?,
word_position_docids: env.create_database(Some("word-position-docids"))?,
word_four_positions_docids: env.create_database(Some("word-four-positions-docids"))?,
word_attribute_docids: env.create_database(Some("word-attribute-docids"))?,
documents: env.create_database(Some("documents"))?,
})