MeiliSearch/milli/src/search/criteria/asc_desc.rs

290 lines
11 KiB
Rust

use std::mem::take;
use itertools::Itertools;
use log::debug;
use ordered_float::OrderedFloat;
use roaring::RoaringBitmap;
use super::{Criterion, CriterionParameters, CriterionResult};
use crate::search::criteria::{resolve_query_tree, CriteriaBuilder};
use crate::search::facet::{FacetNumberIter, FacetStringIter};
use crate::search::query_tree::Operation;
use crate::{FieldId, Index, Result};
/// Threshold on the number of candidates that will make
/// the system to choose between one algorithm or another.
const CANDIDATES_THRESHOLD: u64 = 1000;
pub struct AscDesc<'t> {
index: &'t Index,
rtxn: &'t heed::RoTxn<'t>,
field_name: String,
field_id: Option<FieldId>,
is_ascending: bool,
query_tree: Option<Operation>,
candidates: Box<dyn Iterator<Item = heed::Result<RoaringBitmap>> + 't>,
allowed_candidates: RoaringBitmap,
bucket_candidates: RoaringBitmap,
faceted_candidates: RoaringBitmap,
parent: Box<dyn Criterion + 't>,
}
impl<'t> AscDesc<'t> {
pub fn asc(
index: &'t Index,
rtxn: &'t heed::RoTxn,
parent: Box<dyn Criterion + 't>,
field_name: String,
) -> Result<Self> {
Self::new(index, rtxn, parent, field_name, true)
}
pub fn desc(
index: &'t Index,
rtxn: &'t heed::RoTxn,
parent: Box<dyn Criterion + 't>,
field_name: String,
) -> Result<Self> {
Self::new(index, rtxn, parent, field_name, false)
}
fn new(
index: &'t Index,
rtxn: &'t heed::RoTxn,
parent: Box<dyn Criterion + 't>,
field_name: String,
is_ascending: bool,
) -> Result<Self> {
let fields_ids_map = index.fields_ids_map(rtxn)?;
let field_id = fields_ids_map.id(&field_name);
let faceted_candidates = match field_id {
Some(field_id) => {
let number_faceted = index.number_faceted_documents_ids(rtxn, field_id)?;
let string_faceted = index.string_faceted_documents_ids(rtxn, field_id)?;
number_faceted | string_faceted
}
None => RoaringBitmap::default(),
};
Ok(AscDesc {
index,
rtxn,
field_name,
field_id,
is_ascending,
query_tree: None,
candidates: Box::new(std::iter::empty()),
allowed_candidates: RoaringBitmap::new(),
faceted_candidates,
bucket_candidates: RoaringBitmap::new(),
parent,
})
}
}
impl<'t> Criterion for AscDesc<'t> {
#[logging_timer::time("AscDesc::{}")]
fn next(&mut self, params: &mut CriterionParameters) -> Result<Option<CriterionResult>> {
// remove excluded candidates when next is called, instead of doing it in the loop.
self.allowed_candidates -= params.excluded_candidates;
loop {
debug!(
"Facet {}({}) iteration",
if self.is_ascending { "Asc" } else { "Desc" },
self.field_name
);
match self.candidates.next().transpose()? {
None if !self.allowed_candidates.is_empty() => {
return Ok(Some(CriterionResult {
query_tree: self.query_tree.clone(),
candidates: Some(take(&mut self.allowed_candidates)),
filtered_candidates: None,
bucket_candidates: Some(take(&mut self.bucket_candidates)),
}));
}
None => match self.parent.next(params)? {
Some(CriterionResult {
query_tree,
candidates,
filtered_candidates,
bucket_candidates,
}) => {
self.query_tree = query_tree;
let mut candidates = match (&self.query_tree, candidates) {
(_, Some(candidates)) => candidates,
(Some(qt), None) => {
let context = CriteriaBuilder::new(&self.rtxn, &self.index)?;
resolve_query_tree(&context, qt, params.wdcache)?
}
(None, None) => self.index.documents_ids(self.rtxn)?,
};
if let Some(filtered_candidates) = filtered_candidates {
candidates &= filtered_candidates;
}
match bucket_candidates {
Some(bucket_candidates) => self.bucket_candidates |= bucket_candidates,
None => self.bucket_candidates |= &candidates,
}
if candidates.is_empty() {
continue;
}
self.allowed_candidates = &candidates - params.excluded_candidates;
self.candidates = match self.field_id {
Some(field_id) => facet_ordered(
self.index,
self.rtxn,
field_id,
self.is_ascending,
candidates & &self.faceted_candidates,
)?,
None => Box::new(std::iter::empty()),
};
}
None => return Ok(None),
},
Some(mut candidates) => {
candidates -= params.excluded_candidates;
self.allowed_candidates -= &candidates;
return Ok(Some(CriterionResult {
query_tree: self.query_tree.clone(),
candidates: Some(candidates),
filtered_candidates: None,
bucket_candidates: Some(take(&mut self.bucket_candidates)),
}));
}
}
}
}
}
/// Returns an iterator over groups of the given candidates in ascending or descending order.
///
/// It will either use an iterative or a recursive method on the whole facet database depending
/// on the number of candidates to rank.
fn facet_ordered<'t>(
index: &'t Index,
rtxn: &'t heed::RoTxn,
field_id: FieldId,
is_ascending: bool,
candidates: RoaringBitmap,
) -> Result<Box<dyn Iterator<Item = heed::Result<RoaringBitmap>> + 't>> {
if candidates.len() <= CANDIDATES_THRESHOLD {
let number_iter = iterative_facet_number_ordered_iter(
index,
rtxn,
field_id,
is_ascending,
candidates.clone(),
)?;
let string_iter =
iterative_facet_string_ordered_iter(index, rtxn, field_id, is_ascending, candidates)?;
Ok(Box::new(number_iter.chain(string_iter).map(Ok)) as Box<dyn Iterator<Item = _>>)
} else {
let facet_number_fn = if is_ascending {
FacetNumberIter::new_reducing
} else {
FacetNumberIter::new_reverse_reducing
};
let number_iter = facet_number_fn(rtxn, index, field_id, candidates.clone())?
.map(|res| res.map(|(_, docids)| docids));
let facet_string_fn = if is_ascending {
FacetStringIter::new_reducing
} else {
FacetStringIter::new_reverse_reducing
};
let string_iter = facet_string_fn(rtxn, index, field_id, candidates)?
.map(|res| res.map(|(_, _, docids)| docids));
Ok(Box::new(number_iter.chain(string_iter)))
}
}
/// Fetch the whole list of candidates facet number values one by one and order them by it.
///
/// This function is fast when the amount of candidates to rank is small.
fn iterative_facet_number_ordered_iter<'t>(
index: &'t Index,
rtxn: &'t heed::RoTxn,
field_id: FieldId,
is_ascending: bool,
candidates: RoaringBitmap,
) -> Result<impl Iterator<Item = RoaringBitmap> + 't> {
let mut docids_values = Vec::with_capacity(candidates.len() as usize);
for docid in candidates.iter() {
let left = (field_id, docid, f64::MIN);
let right = (field_id, docid, f64::MAX);
let mut iter = index.field_id_docid_facet_f64s.range(rtxn, &(left..=right))?;
let entry = if is_ascending { iter.next() } else { iter.last() };
if let Some(((_, _, value), ())) = entry.transpose()? {
docids_values.push((docid, OrderedFloat(value)));
}
}
docids_values.sort_unstable_by_key(|(_, v)| *v);
let iter = docids_values.into_iter();
let iter = if is_ascending {
Box::new(iter) as Box<dyn Iterator<Item = _>>
} else {
Box::new(iter.rev())
};
// The itertools GroupBy iterator doesn't provide an owned version, we are therefore
// required to collect the result into an owned collection (a Vec).
// https://github.com/rust-itertools/itertools/issues/499
let vec: Vec<_> = iter
.group_by(|(_, v)| *v)
.into_iter()
.map(|(_, ids)| ids.map(|(id, _)| id).collect())
.collect();
Ok(vec.into_iter())
}
/// Fetch the whole list of candidates facet string values one by one and order them by it.
///
/// This function is fast when the amount of candidates to rank is small.
fn iterative_facet_string_ordered_iter<'t>(
index: &'t Index,
rtxn: &'t heed::RoTxn,
field_id: FieldId,
is_ascending: bool,
candidates: RoaringBitmap,
) -> Result<impl Iterator<Item = RoaringBitmap> + 't> {
let mut docids_values = Vec::with_capacity(candidates.len() as usize);
for docid in candidates.iter() {
let left = (field_id, docid, "");
let right = (field_id, docid.saturating_add(1), "");
// FIXME Doing this means that it will never be possible to retrieve
// the document with id 2^32, not sure this is a real problem.
let mut iter = index.field_id_docid_facet_strings.range(rtxn, &(left..right))?;
let entry = if is_ascending { iter.next() } else { iter.last() };
if let Some(((_, _, value), _)) = entry.transpose()? {
docids_values.push((docid, value));
}
}
docids_values.sort_unstable_by_key(|(_, v)| *v);
let iter = docids_values.into_iter();
let iter = if is_ascending {
Box::new(iter) as Box<dyn Iterator<Item = _>>
} else {
Box::new(iter.rev())
};
// The itertools GroupBy iterator doesn't provide an owned version, we are therefore
// required to collect the result into an owned collection (a Vec).
// https://github.com/rust-itertools/itertools/issues/499
let vec: Vec<_> = iter
.group_by(|(_, v)| *v)
.into_iter()
.map(|(_, ids)| ids.map(|(id, _)| id).collect())
.collect();
Ok(vec.into_iter())
}