From 8fdf860c17efd131504beba7c8ecfdd3b20335fb Mon Sep 17 00:00:00 2001
From: many <maxime@meilisearch.com>
Date: Thu, 12 Aug 2021 11:29:20 +0200
Subject: [PATCH] Remove max values by facet limit for facet distribution

---
 milli/src/search/facet/facet_distribution.rs | 47 ++------------------
 1 file changed, 3 insertions(+), 44 deletions(-)

diff --git a/milli/src/search/facet/facet_distribution.rs b/milli/src/search/facet/facet_distribution.rs
index bfbea76c3..91bf21cf7 100644
--- a/milli/src/search/facet/facet_distribution.rs
+++ b/milli/src/search/facet/facet_distribution.rs
@@ -1,6 +1,6 @@
 use std::collections::{BTreeMap, HashSet};
 use std::ops::Bound::Unbounded;
-use std::{cmp, fmt, mem};
+use std::{fmt, mem};
 
 use heed::types::ByteSlice;
 use roaring::RoaringBitmap;
@@ -13,14 +13,6 @@ use crate::heed_codec::facet::{
 use crate::search::facet::{FacetNumberIter, FacetNumberRange, FacetStringIter};
 use crate::{FieldId, Index, Result};
 
-/// The default number of values by facets that will
-/// be fetched from the key-value store.
-const DEFAULT_VALUES_BY_FACET: usize = 100;
-
-/// The hard limit in the number of values by facets that will be fetched from
-/// the key-value store. Searching for more values could slow down the engine.
-const MAX_VALUES_BY_FACET: usize = 1000;
-
 /// Threshold on the number of candidates that will make
 /// the system to choose between one algorithm or another.
 const CANDIDATES_THRESHOLD: u64 = 3000;
@@ -28,20 +20,13 @@ const CANDIDATES_THRESHOLD: u64 = 3000;
 pub struct FacetDistribution<'a> {
     facets: Option<HashSet<String>>,
     candidates: Option<RoaringBitmap>,
-    max_values_by_facet: usize,
     rtxn: &'a heed::RoTxn<'a>,
     index: &'a Index,
 }
 
 impl<'a> FacetDistribution<'a> {
     pub fn new(rtxn: &'a heed::RoTxn, index: &'a Index) -> FacetDistribution<'a> {
-        FacetDistribution {
-            facets: None,
-            candidates: None,
-            max_values_by_facet: DEFAULT_VALUES_BY_FACET,
-            rtxn,
-            index,
-        }
+        FacetDistribution { facets: None, candidates: None, rtxn, index }
     }
 
     pub fn facets<I: IntoIterator<Item = A>, A: AsRef<str>>(&mut self, names: I) -> &mut Self {
@@ -54,11 +39,6 @@ impl<'a> FacetDistribution<'a> {
         self
     }
 
-    pub fn max_values_by_facet(&mut self, max: usize) -> &mut Self {
-        self.max_values_by_facet = cmp::min(max, MAX_VALUES_BY_FACET);
-        self
-    }
-
     /// There is a small amount of candidates OR we ask for facet string values so we
     /// decide to iterate over the facet values of each one of them, one by one.
     fn facet_distribution_from_documents(
@@ -72,7 +52,6 @@ impl<'a> FacetDistribution<'a> {
             FacetType::Number => {
                 let mut key_buffer: Vec<_> = field_id.to_be_bytes().iter().copied().collect();
 
-                let distribution_prelength = distribution.len();
                 let db = self.index.field_id_docid_facet_f64s;
                 for docid in candidates.into_iter() {
                     key_buffer.truncate(mem::size_of::<FieldId>());
@@ -85,9 +64,6 @@ impl<'a> FacetDistribution<'a> {
                     for result in iter {
                         let ((_, _, value), ()) = result?;
                         *distribution.entry(value.to_string()).or_insert(0) += 1;
-                        if distribution.len() - distribution_prelength == self.max_values_by_facet {
-                            break;
-                        }
                     }
                 }
             }
@@ -110,10 +86,6 @@ impl<'a> FacetDistribution<'a> {
                             .entry(normalized_value)
                             .or_insert_with(|| (original_value, 0));
                         *count += 1;
-
-                        if normalized_distribution.len() == self.max_values_by_facet {
-                            break;
-                        }
                     }
                 }
 
@@ -144,9 +116,6 @@ impl<'a> FacetDistribution<'a> {
             if !docids.is_empty() {
                 distribution.insert(value.to_string(), docids.len());
             }
-            if distribution.len() == self.max_values_by_facet {
-                break;
-            }
         }
 
         Ok(())
@@ -167,9 +136,6 @@ impl<'a> FacetDistribution<'a> {
             if !docids.is_empty() {
                 distribution.insert(original.to_string(), docids.len());
             }
-            if distribution.len() == self.max_values_by_facet {
-                break;
-            }
         }
 
         Ok(())
@@ -189,9 +155,6 @@ impl<'a> FacetDistribution<'a> {
         for result in range {
             let ((_, _, value, _), docids) = result?;
             distribution.insert(value.to_string(), docids.len());
-            if distribution.len() == self.max_values_by_facet {
-                break;
-            }
         }
 
         let iter = self
@@ -205,9 +168,6 @@ impl<'a> FacetDistribution<'a> {
         for result in iter {
             let ((_, normalized_value), (original_value, docids)) = result?;
             normalized_distribution.insert(normalized_value, (original_value, docids.len()));
-            if distribution.len() == self.max_values_by_facet {
-                break;
-            }
         }
 
         let iter = normalized_distribution
@@ -289,12 +249,11 @@ impl<'a> FacetDistribution<'a> {
 
 impl fmt::Debug for FacetDistribution<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let FacetDistribution { facets, candidates, max_values_by_facet, rtxn: _, index: _ } = self;
+        let FacetDistribution { facets, candidates, rtxn: _, index: _ } = self;
 
         f.debug_struct("FacetDistribution")
             .field("facets", facets)
             .field("candidates", candidates)
-            .field("max_values_by_facet", max_values_by_facet)
             .finish()
     }
 }