Add range search and incremental indexing algorithm

milli/Cargo.toml

@@ -54,7 +54,7 @@ big_s = "1.0.2"
 insta = "1.21.0"
 maplit = "1.0.2"
 md5 = "0.7.0"
-rand = "0.8.5"
+rand = {version = "0.8.5", features = ["small_rng"] }
 
 [features]
 default = [ "charabia/default" ]

milli/src/search/facet/facet_distribution_iter.rs

@@ -1,8 +1,8 @@
+use crate::heed_codec::facet::new::{FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice};
+use crate::Result;
 use roaring::RoaringBitmap;
 use std::ops::ControlFlow;
 
-use crate::heed_codec::facet::new::{FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice};
-
 use super::{get_first_facet_value, get_highest_level};
 
 pub fn iterate_over_facet_distribution<'t, CB>(
@@ -11,18 +11,19 @@ pub fn iterate_over_facet_distribution<'t, CB>(
     field_id: u16,
     candidates: &RoaringBitmap,
     callback: CB,
-) where
+) -> Result<()>
+where
     CB: FnMut(&'t [u8], u64) -> ControlFlow<()>,
 {
     let mut fd = FacetDistribution { rtxn, db, field_id, callback };
     let highest_level =
-        get_highest_level(rtxn, &db.remap_key_type::<FacetKeyCodec<MyByteSlice>>(), field_id);
+        get_highest_level(rtxn, &db.remap_key_type::<FacetKeyCodec<MyByteSlice>>(), field_id)?;
 
-    if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(rtxn, db, field_id) {
+    if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(rtxn, db, field_id)? {
         fd.iterate(candidates, highest_level, first_bound, usize::MAX);
-        return;
+        return Ok(());
     } else {
-        return;
+        return Ok(());
     }
 }
 
@@ -45,26 +46,26 @@ where
         candidates: &RoaringBitmap,
         starting_bound: &'t [u8],
         group_size: usize,
-    ) -> ControlFlow<()> {
+    ) -> Result<ControlFlow<()>> {
         let starting_key =
             FacetKey { field_id: self.field_id, level: 0, left_bound: starting_bound };
-        let iter = self.db.range(self.rtxn, &(starting_key..)).unwrap().take(group_size);
+        let iter = self.db.range(self.rtxn, &(starting_key..))?.take(group_size);
         for el in iter {
-            let (key, value) = el.unwrap();
+            let (key, value) = el?;
             // The range is unbounded on the right and the group size for the highest level is MAX,
             // so we need to check that we are not iterating over the next field id
             if key.field_id != self.field_id {
-                return ControlFlow::Break(());
+                return Ok(ControlFlow::Break(()));
             }
             let docids_in_common = value.bitmap.intersection_len(candidates);
             if docids_in_common > 0 {
                 match (self.callback)(key.left_bound, docids_in_common) {
                     ControlFlow::Continue(_) => {}
-                    ControlFlow::Break(_) => return ControlFlow::Break(()),
+                    ControlFlow::Break(_) => return Ok(ControlFlow::Break(())),
                 }
             }
         }
-        return ControlFlow::Continue(());
+        return Ok(ControlFlow::Continue(()));
     }
     fn iterate(
         &mut self,
@@ -72,7 +73,7 @@ where
         level: u8,
         starting_bound: &'t [u8],
         group_size: usize,
-    ) -> ControlFlow<()> {
+    ) -> Result<ControlFlow<()>> {
         if level == 0 {
             return self.iterate_level_0(candidates, starting_bound, group_size);
         }
@@ -84,34 +85,42 @@ where
             // The range is unbounded on the right and the group size for the highest level is MAX,
             // so we need to check that we are not iterating over the next field id
             if key.field_id != self.field_id {
-                return ControlFlow::Break(());
+                return Ok(ControlFlow::Break(()));
             }
             let docids_in_common = value.bitmap & candidates;
             if docids_in_common.len() > 0 {
-                let cf =
-                    self.iterate(&docids_in_common, level - 1, key.left_bound, value.size as usize);
+                let cf = self.iterate(
+                    &docids_in_common,
+                    level - 1,
+                    key.left_bound,
+                    value.size as usize,
+                )?;
                 match cf {
                     ControlFlow::Continue(_) => {}
-                    ControlFlow::Break(_) => return ControlFlow::Break(()),
+                    ControlFlow::Break(_) => return Ok(ControlFlow::Break(())),
                 }
             }
         }
 
-        return ControlFlow::Continue(());
+        return Ok(ControlFlow::Continue(()));
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::{codec::U16Codec, Index};
     use heed::BytesDecode;
+    use rand::{rngs::SmallRng, Rng, SeedableRng};
     use roaring::RoaringBitmap;
     use std::ops::ControlFlow;
 
+    use crate::{
+        heed_codec::facet::new::ordered_f64_codec::OrderedF64Codec, search::facet::test::FacetIndex,
+    };
+
     use super::iterate_over_facet_distribution;
 
-    fn get_simple_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    fn get_simple_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
         for i in 0..256u16 {
             let mut bitmap = RoaringBitmap::new();
@@ -121,18 +130,19 @@ mod tests {
         txn.commit().unwrap();
         index
     }
-    fn get_random_looking_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    fn get_random_looking_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
 
-        let rng = fastrand::Rng::with_seed(0);
-        let keys = std::iter::from_fn(|| Some(rng.u32(..256))).take(128).collect::<Vec<u32>>();
+        let rng = rand::rngs::SmallRng::from_seed([0; 32]);
+        let keys =
+            std::iter::from_fn(|| Some(rng.gen_range(0..256))).take(128).collect::<Vec<u32>>();
 
         for (_i, key) in keys.into_iter().enumerate() {
             let mut bitmap = RoaringBitmap::new();
             bitmap.insert(key);
-            bitmap.insert(key + 100);
-            index.insert(&mut txn, 0, &(key as u16), &bitmap);
+            bitmap.insert(key + 100.);
+            index.insert(&mut txn, 0, &(key as f64), &bitmap);
         }
         txn.commit().unwrap();
         index
@@ -156,7 +166,7 @@ mod tests {
                 0,
                 &candidates,
                 |facet, count| {
-                    let facet = U16Codec::bytes_decode(facet).unwrap();
+                    let facet = OrderedF64Codec::bytes_decode(facet).unwrap();
                     results.push_str(&format!("{facet}: {count}\n"));
                     ControlFlow::Continue(())
                 },
@@ -180,7 +190,7 @@ mod tests {
                 0,
                 &candidates,
                 |facet, count| {
-                    let facet = U16Codec::bytes_decode(facet).unwrap();
+                    let facet = OrderedF64Codec::bytes_decode(facet).unwrap();
                     if nbr_facets == 100 {
                         return ControlFlow::Break(());
                     } else {

milli/src/search/facet/facet_range_search.rs

@@ -0,0 +1,451 @@
+use heed::BytesEncode;
+use roaring::RoaringBitmap;
+use std::ops::Bound;
+use std::ops::RangeBounds;
+
+use crate::heed_codec::facet::new::FacetGroupValueCodec;
+use crate::heed_codec::facet::new::FacetKey;
+use crate::heed_codec::facet::new::FacetKeyCodec;
+use crate::heed_codec::facet::new::MyByteSlice;
+use crate::Result;
+
+use super::get_first_facet_value;
+use super::get_highest_level;
+use super::get_last_facet_value;
+
+pub fn find_docids_of_facet_within_bounds<'t, BoundCodec>(
+    rtxn: &'t heed::RoTxn<'t>,
+    db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
+    field_id: u16,
+    left: &'t Bound<<BoundCodec as BytesEncode<'t>>::EItem>,
+    right: &'t Bound<<BoundCodec as BytesEncode<'t>>::EItem>,
+) -> Result<RoaringBitmap>
+where
+    BoundCodec: for<'a> BytesEncode<'a>,
+    for<'a> <BoundCodec as BytesEncode<'a>>::EItem: Sized,
+{
+    let inner;
+    let left = match left {
+        Bound::Included(left) => {
+            inner = BoundCodec::bytes_encode(left).unwrap();
+            Bound::Included(inner.as_ref())
+        }
+        Bound::Excluded(left) => {
+            inner = BoundCodec::bytes_encode(left).unwrap();
+            Bound::Excluded(inner.as_ref())
+        }
+        Bound::Unbounded => Bound::Unbounded,
+    };
+    let inner;
+    let right = match right {
+        Bound::Included(right) => {
+            inner = BoundCodec::bytes_encode(right).unwrap();
+            Bound::Included(inner.as_ref())
+        }
+        Bound::Excluded(right) => {
+            inner = BoundCodec::bytes_encode(right).unwrap();
+            Bound::Excluded(inner.as_ref())
+        }
+        Bound::Unbounded => Bound::Unbounded,
+    };
+
+    let mut docids = RoaringBitmap::new();
+    let mut f = FacetRangeSearch { rtxn, db, field_id, left, right, docids: &mut docids };
+    let highest_level = get_highest_level(rtxn, db, field_id)?;
+
+    if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(rtxn, db, field_id)? {
+        let last_bound = get_last_facet_value::<MyByteSlice>(rtxn, db, field_id)?.unwrap();
+        f.run(highest_level, first_bound, Bound::Included(last_bound), usize::MAX)?;
+        Ok(docids)
+    } else {
+        return Ok(RoaringBitmap::new());
+    }
+}
+
+/// Fetch the document ids that have a facet with a value between the two given bounds
+struct FacetRangeSearch<'t, 'b, 'bitmap> {
+    rtxn: &'t heed::RoTxn<'t>,
+    db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
+    field_id: u16,
+    left: Bound<&'b [u8]>,
+    right: Bound<&'b [u8]>,
+    docids: &'bitmap mut RoaringBitmap,
+}
+impl<'t, 'b, 'bitmap> FacetRangeSearch<'t, 'b, 'bitmap> {
+    fn run_level_0(&mut self, starting_left_bound: &'t [u8], group_size: usize) -> Result<()> {
+        let left_key =
+            FacetKey { field_id: self.field_id, level: 0, left_bound: starting_left_bound };
+        let iter = self.db.range(&self.rtxn, &(left_key..))?.take(group_size);
+        for el in iter {
+            let (key, value) = el?;
+            // the right side of the iter range is unbounded, so we need to make sure that we are not iterating
+            // on the next field id
+            if key.field_id != self.field_id {
+                return Ok(());
+            }
+            let should_skip = {
+                match self.left {
+                    Bound::Included(left) => left > key.left_bound,
+                    Bound::Excluded(left) => left >= key.left_bound,
+                    Bound::Unbounded => false,
+                }
+            };
+            if should_skip {
+                continue;
+            }
+            let should_stop = {
+                match self.right {
+                    Bound::Included(right) => right < key.left_bound,
+                    Bound::Excluded(right) => right <= key.left_bound,
+                    Bound::Unbounded => false,
+                }
+            };
+            if should_stop {
+                break;
+            }
+
+            if RangeBounds::<&[u8]>::contains(&(self.left, self.right), &key.left_bound) {
+                *self.docids |= value.bitmap;
+            }
+        }
+        Ok(())
+    }
+
+    /// Recursive part of the algorithm for level > 0
+    fn run(
+        &mut self,
+        level: u8,
+        starting_left_bound: &'t [u8],
+        rightmost_bound: Bound<&'t [u8]>,
+        group_size: usize,
+    ) -> Result<()> {
+        if level == 0 {
+            return self.run_level_0(starting_left_bound, group_size);
+        }
+
+        let left_key = FacetKey { field_id: self.field_id, level, left_bound: starting_left_bound };
+        let mut iter = self.db.range(&self.rtxn, &(left_key..))?.take(group_size);
+
+        let (mut previous_key, mut previous_value) = iter.next().unwrap()?;
+        for el in iter {
+            let (next_key, next_value) = el?;
+            // the right of the iter range is unbounded, so we need to make sure that we are not iterating
+            // on the next field id
+            if next_key.field_id != self.field_id {
+                return Ok(());
+            }
+            // now, do we skip, stop, or visit?
+            let should_skip = {
+                match self.left {
+                    Bound::Included(left) => left >= next_key.left_bound,
+                    Bound::Excluded(left) => left >= next_key.left_bound, // TODO: use > instead?
+                    Bound::Unbounded => false,
+                }
+            };
+            if should_skip {
+                previous_key = next_key;
+                previous_value = next_value;
+                continue;
+            }
+
+            // should we stop?
+            let should_stop = {
+                match self.right {
+                    Bound::Included(right) => right < previous_key.left_bound,
+                    Bound::Excluded(right) => right <= previous_key.left_bound,
+                    Bound::Unbounded => false,
+                }
+            };
+            if should_stop {
+                return Ok(());
+            }
+            // should we take the whole thing, without recursing down?
+            let should_take_whole_group = {
+                let left_condition = match self.left {
+                    Bound::Included(left) => previous_key.left_bound >= left,
+                    Bound::Excluded(left) => previous_key.left_bound > left,
+                    Bound::Unbounded => true,
+                };
+                let right_condition = match self.right {
+                    Bound::Included(right) => next_key.left_bound <= right,
+                    Bound::Excluded(right) => next_key.left_bound <= right,
+                    Bound::Unbounded => true,
+                };
+                left_condition && right_condition
+            };
+            if should_take_whole_group {
+                *self.docids |= &previous_value.bitmap;
+                previous_key = next_key;
+                previous_value = next_value;
+                continue;
+            }
+
+            let level = level - 1;
+            let starting_left_bound = previous_key.left_bound;
+            let rightmost_bound = Bound::Excluded(next_key.left_bound);
+            let group_size = previous_value.size as usize;
+
+            self.run(level, starting_left_bound, rightmost_bound, group_size)?;
+
+            previous_key = next_key;
+            previous_value = next_value;
+        }
+        // previous_key/previous_value are the last element
+
+        // now, do we skip, stop, or visit?
+        let should_skip = {
+            match (self.left, rightmost_bound) {
+                (Bound::Included(left), Bound::Included(right)) => left > right,
+                (Bound::Included(left), Bound::Excluded(right)) => left >= right,
+                (Bound::Excluded(left), Bound::Included(right) | Bound::Excluded(right)) => {
+                    left >= right
+                }
+                (Bound::Unbounded, _) => false,
+                (_, Bound::Unbounded) => false, // should never run?
+            }
+        };
+        if should_skip {
+            return Ok(());
+        }
+
+        // should we stop?
+        let should_stop = {
+            match self.right {
+                Bound::Included(right) => right <= previous_key.left_bound,
+                Bound::Excluded(right) => right < previous_key.left_bound,
+                Bound::Unbounded => false,
+            }
+        };
+        if should_stop {
+            return Ok(());
+        }
+        // should we take the whole thing, without recursing down?
+        let should_take_whole_group = {
+            let left_condition = match self.left {
+                Bound::Included(left) => previous_key.left_bound >= left,
+                Bound::Excluded(left) => previous_key.left_bound > left,
+                Bound::Unbounded => true,
+            };
+            let right_condition = match (self.right, rightmost_bound) {
+                (Bound::Included(right), Bound::Included(rightmost)) => rightmost <= right,
+                (Bound::Included(right), Bound::Excluded(rightmost)) => rightmost < right,
+                // e.g. x < 8 and rightmost is <= y
+                // condition met if rightmost < 8
+                (Bound::Excluded(right), Bound::Included(rightmost)) => rightmost < right,
+                // e.g. x < 8 and rightmost is < y
+                // condition met only if y <= 8?
+                (Bound::Excluded(right), Bound::Excluded(rightmost)) => rightmost <= right,
+                // e.g. x < inf. , so yes we take the whole thing
+                (Bound::Unbounded, _) => true,
+                // e.g. x < 7 , righmost is inf
+                (_, Bound::Unbounded) => false, // panic?
+            };
+            left_condition && right_condition
+        };
+        if should_take_whole_group {
+            *self.docids |= &previous_value.bitmap;
+        } else {
+            let level = level - 1;
+            let starting_left_bound = previous_key.left_bound;
+            let group_size = previous_value.size as usize;
+
+            self.run(level, starting_left_bound, rightmost_bound, group_size)?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        heed_codec::facet::new::ordered_f64_codec::OrderedF64Codec,
+        search::facet::test::FacetIndex, snapshot_tests::display_bitmap,
+    };
+    use rand::{Rng, SeedableRng};
+    use roaring::RoaringBitmap;
+    use std::ops::Bound;
+
+    use super::find_docids_of_facet_within_bounds;
+
+    fn get_simple_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
+        let mut txn = index.env.write_txn().unwrap();
+        for i in 0..256u16 {
+            let mut bitmap = RoaringBitmap::new();
+            bitmap.insert(i as u32);
+            index.insert(&mut txn, 0, &(i as f64), &bitmap);
+        }
+        txn.commit().unwrap();
+        index
+    }
+    fn get_random_looking_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
+        let mut txn = index.env.write_txn().unwrap();
+
+        let rng = rand::rngs::SmallRng::from_seed([0; 32]);
+        let keys =
+            std::iter::from_fn(|| Some(rng.gen_range(0..256))).take(128).collect::<Vec<u32>>();
+
+        for (_i, key) in keys.into_iter().enumerate() {
+            let mut bitmap = RoaringBitmap::new();
+            bitmap.insert(key);
+            bitmap.insert(key + 100);
+            index.insert(&mut txn, 0, &(key as f64), &bitmap);
+        }
+        txn.commit().unwrap();
+        index
+    }
+
+    #[test]
+    fn random_looking_index_snap() {
+        let index = get_random_looking_index();
+        insta::assert_display_snapshot!(index)
+    }
+    #[test]
+    fn filter_range_increasing() {
+        let indexes = [get_simple_index(), get_random_looking_index()];
+        for (i, index) in indexes.into_iter().enumerate() {
+            let txn = index.env.read_txn().unwrap();
+            let mut results = String::new();
+            for i in 0..=255 {
+                let i = i as f64;
+                let start = Bound::Included(0.);
+                let end = Bound::Included(i);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+            insta::assert_snapshot!(
+                format!("filter_range_{i}_increasing_included_bounds"),
+                results
+            );
+            let mut results = String::new();
+            for i in 0..=255 {
+                let i = i as f64;
+                let start = Bound::Excluded(0.);
+                let end = Bound::Excluded(i);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+            insta::assert_snapshot!(
+                format!("filter_range_{i}_increasing_excluded_bounds"),
+                results
+            );
+            txn.commit().unwrap();
+        }
+    }
+    #[test]
+    fn filter_range_decreasing() {
+        let indexes = [get_simple_index(), get_random_looking_index()];
+        for (i, index) in indexes.into_iter().enumerate() {
+            let txn = index.env.read_txn().unwrap();
+
+            let mut results = String::new();
+
+            for i in (0..=255).into_iter().rev() {
+                let i = i as f64;
+                let start = Bound::Included(i);
+                let end = Bound::Included(255.);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+
+            insta::assert_snapshot!(
+                format!("filter_range_{i}_decreasing_included_bounds"),
+                results
+            );
+
+            let mut results = String::new();
+
+            for i in (0..=255).into_iter().rev() {
+                let i = i as f64;
+                let start = Bound::Excluded(i);
+                let end = Bound::Excluded(255.);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+
+            insta::assert_snapshot!(
+                format!("filter_range_{i}_decreasing_excluded_bounds"),
+                results
+            );
+
+            txn.commit().unwrap();
+        }
+    }
+    #[test]
+    fn filter_range_pinch() {
+        let indexes = [get_simple_index(), get_random_looking_index()];
+        for (i, index) in indexes.into_iter().enumerate() {
+            let txn = index.env.read_txn().unwrap();
+
+            let mut results = String::new();
+
+            for i in (0..=128).into_iter().rev() {
+                let i = i as f64;
+                let start = Bound::Included(i);
+                let end = Bound::Included(255. - i);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+
+            insta::assert_snapshot!(format!("filter_range_{i}_pinch_included_bounds"), results);
+
+            let mut results = String::new();
+
+            for i in (0..=128).into_iter().rev() {
+                let i = i as f64;
+                let start = Bound::Excluded(i);
+                let end = Bound::Excluded(255. - i);
+                let docids = find_docids_of_facet_within_bounds::<OrderedF64Codec>(
+                    &txn,
+                    &index.db.content,
+                    0,
+                    &start,
+                    &end,
+                )
+                .unwrap();
+                results.push_str(&format!("{}\n", display_bitmap(&docids)));
+            }
+
+            insta::assert_snapshot!(format!("filter_range_{i}_pinch_excluded_bounds"), results);
+
+            txn.commit().unwrap();
+        }
+    }
+}

milli/src/search/facet/facet_sort_ascending.rs

@@ -1,8 +1,8 @@
-use roaring::RoaringBitmap;
-
 use crate::heed_codec::facet::new::{
     FacetGroupValue, FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice,
 };
+use crate::Result;
+use roaring::RoaringBitmap;
 
 use super::{get_first_facet_value, get_highest_level};
 
@@ -11,20 +11,20 @@ pub fn ascending_facet_sort<'t>(
     db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
     field_id: u16,
     candidates: RoaringBitmap,
-) -> Box<dyn Iterator<Item = (&'t [u8], RoaringBitmap)> + 't> {
+) -> Result<Box<dyn Iterator<Item = Result<(&'t [u8], RoaringBitmap)>> + 't>> {
     let highest_level =
-        get_highest_level(rtxn, &db.remap_key_type::<FacetKeyCodec<MyByteSlice>>(), field_id);
+        get_highest_level(rtxn, &db.remap_key_type::<FacetKeyCodec<MyByteSlice>>(), field_id)?;
     if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(
         rtxn,
         &db.remap_key_type::<FacetKeyCodec<MyByteSlice>>(),
         field_id,
-    ) {
+    )? {
         let first_key = FacetKey { field_id, level: highest_level, left_bound: first_bound };
         let iter = db.range(rtxn, &(first_key..)).unwrap().take(usize::MAX);
 
-        Box::new(AscendingFacetSort { rtxn, db, field_id, stack: vec![(candidates, iter)] })
+        Ok(Box::new(AscendingFacetSort { rtxn, db, field_id, stack: vec![(candidates, iter)] }))
     } else {
-        return Box::new(std::iter::empty());
+        Ok(Box::new(std::iter::empty()))
     }
 }
 
@@ -39,7 +39,7 @@ struct AscendingFacetSort<'t, 'e> {
 }
 
 impl<'t, 'e> Iterator for AscendingFacetSort<'t, 'e> {
-    type Item = (&'t [u8], RoaringBitmap);
+    type Item = Result<(&'t [u8], RoaringBitmap)>;
 
     fn next(&mut self) -> Option<Self::Item> {
         'outer: loop {
@@ -67,15 +67,15 @@ impl<'t, 'e> Iterator for AscendingFacetSort<'t, 'e> {
                     *documents_ids -= &bitmap;
 
                     if level == 0 {
-                        return Some((left_bound, bitmap));
+                        return Some(Ok((left_bound, bitmap)));
                     }
                     let starting_key_below =
                         FacetKey { field_id: self.field_id, level: level - 1, left_bound };
-                    let iter = self
-                        .db
-                        .range(&self.rtxn, &(starting_key_below..))
-                        .unwrap()
-                        .take(group_size as usize);
+                    let iter = match self.db.range(&self.rtxn, &(starting_key_below..)) {
+                        Ok(iter) => iter,
+                        Err(e) => return Some(Err(e.into())),
+                    }
+                    .take(group_size as usize);
 
                     self.stack.push((bitmap, iter));
                     continue 'outer;
@@ -88,14 +88,19 @@ impl<'t, 'e> Iterator for AscendingFacetSort<'t, 'e> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{
-        ascending_facet_sort::ascending_facet_sort, codec::U16Codec, display_bitmap, Index,
-    };
     use heed::BytesDecode;
+    use rand::Rng;
+    use rand::SeedableRng;
     use roaring::RoaringBitmap;
 
-    fn get_simple_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    use crate::{
+        heed_codec::facet::new::ordered_f64_codec::OrderedF64Codec,
+        search::facet::{facet_sort_ascending::ascending_facet_sort, test::FacetIndex},
+        snapshot_tests::display_bitmap,
+    };
+
+    fn get_simple_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
         for i in 0..256u16 {
             let mut bitmap = RoaringBitmap::new();
@@ -105,18 +110,19 @@ mod tests {
         txn.commit().unwrap();
         index
     }
-    fn get_random_looking_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    fn get_random_looking_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
 
-        let rng = fastrand::Rng::with_seed(0);
-        let keys = std::iter::from_fn(|| Some(rng.u32(..256))).take(128).collect::<Vec<u32>>();
+        let rng = rand::rngs::SmallRng::from_seed([0; 32]);
+        let keys =
+            std::iter::from_fn(|| Some(rng.gen_range(0..256))).take(128).collect::<Vec<u32>>();
 
         for (_i, key) in keys.into_iter().enumerate() {
             let mut bitmap = RoaringBitmap::new();
             bitmap.insert(key);
             bitmap.insert(key + 100);
-            index.insert(&mut txn, 0, &(key as u16), &bitmap);
+            index.insert(&mut txn, 0, &(key as f64), &bitmap);
         }
         txn.commit().unwrap();
         index
@@ -136,7 +142,7 @@ mod tests {
             let mut results = String::new();
             let iter = ascending_facet_sort(&txn, &index.db.content, 0, candidates);
             for (facet, docids) in iter {
-                let facet = U16Codec::bytes_decode(facet).unwrap();
+                let facet = OrderedF64Codec::bytes_decode(facet).unwrap();
                 results.push_str(&format!("{facet}: {}\n", display_bitmap(&docids)));
             }
             insta::assert_snapshot!(format!("filter_sort_{i}_ascending"), results);

milli/src/search/facet/facet_sort_descending.rs

@@ -1,10 +1,10 @@
 use std::ops::Bound;
 
-use roaring::RoaringBitmap;
-
 use crate::heed_codec::facet::new::{
     FacetGroupValue, FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice,
 };
+use crate::Result;
+use roaring::RoaringBitmap;
 
 use super::{get_first_facet_value, get_highest_level, get_last_facet_value};
 
@@ -13,21 +13,21 @@ fn descending_facet_sort<'t>(
     db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
     field_id: u16,
     candidates: RoaringBitmap,
-) -> Box<dyn Iterator<Item = (&'t [u8], RoaringBitmap)> + 't> {
-    let highest_level = get_highest_level(rtxn, db, field_id);
-    if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(rtxn, db, field_id) {
+) -> Result<Box<dyn Iterator<Item = Result<(&'t [u8], RoaringBitmap)>> + 't>> {
+    let highest_level = get_highest_level(rtxn, db, field_id)?;
+    if let Some(first_bound) = get_first_facet_value::<MyByteSlice>(rtxn, db, field_id)? {
         let first_key = FacetKey { field_id, level: highest_level, left_bound: first_bound };
-        let last_bound = get_last_facet_value::<MyByteSlice>(rtxn, db, field_id).unwrap();
+        let last_bound = get_last_facet_value::<MyByteSlice>(rtxn, db, field_id)?.unwrap();
         let last_key = FacetKey { field_id, level: highest_level, left_bound: last_bound };
-        let iter = db.rev_range(rtxn, &(first_key..=last_key)).unwrap().take(usize::MAX);
-        Box::new(DescendingFacetSort {
+        let iter = db.rev_range(rtxn, &(first_key..=last_key))?.take(usize::MAX);
+        Ok(Box::new(DescendingFacetSort {
             rtxn,
             db,
             field_id,
             stack: vec![(candidates, iter, Bound::Included(last_bound))],
-        })
+        }))
     } else {
-        return Box::new(std::iter::empty());
+        Ok(Box::new(std::iter::empty()))
     }
 }
 
@@ -43,7 +43,7 @@ struct DescendingFacetSort<'t> {
 }
 
 impl<'t> Iterator for DescendingFacetSort<'t> {
-    type Item = (&'t [u8], RoaringBitmap);
+    type Item = Result<(&'t [u8], RoaringBitmap)>;
 
     fn next(&mut self) -> Option<Self::Item> {
         'outer: loop {
@@ -70,7 +70,7 @@ impl<'t> Iterator for DescendingFacetSort<'t> {
                     *documents_ids -= &bitmap;
 
                     if level == 0 {
-                        return Some((left_bound, bitmap));
+                        return Some(Ok((left_bound, bitmap)));
                     }
                     let starting_key_below = FacetKey { field_id, level: level - 1, left_bound };
 
@@ -89,14 +89,14 @@ impl<'t> Iterator for DescendingFacetSort<'t> {
                     };
                     let prev_right_bound = *right_bound;
                     *right_bound = Bound::Excluded(left_bound);
-                    let iter = self
-                        .db
-                        .rev_range(
-                            &self.rtxn,
-                            &(Bound::Included(starting_key_below), end_key_kelow),
-                        )
-                        .unwrap()
-                        .take(group_size as usize);
+                    let iter = match self.db.rev_range(
+                        &self.rtxn,
+                        &(Bound::Included(starting_key_below), end_key_kelow),
+                    ) {
+                        Ok(iter) => iter,
+                        Err(e) => return Some(Err(e.into())),
+                    }
+                    .take(group_size as usize);
 
                     self.stack.push((bitmap, iter, prev_right_bound));
                     continue 'outer;
@@ -110,16 +110,20 @@ impl<'t> Iterator for DescendingFacetSort<'t> {
 
 #[cfg(test)]
 mod tests {
-    use crate::{
-        codec::{MyByteSlice, U16Codec},
-        descending_facet_sort::descending_facet_sort,
-        display_bitmap, FacetKeyCodec, Index,
-    };
+
     use heed::BytesDecode;
+    use rand::Rng;
+    use rand::SeedableRng;
     use roaring::RoaringBitmap;
 
-    fn get_simple_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    use crate::{
+        heed_codec::facet::new::{ordered_f64_codec::OrderedF64Codec, FacetKeyCodec, MyByteSlice},
+        search::facet::{facet_sort_descending::descending_facet_sort, test::FacetIndex},
+        snapshot_tests::display_bitmap,
+    };
+
+    fn get_simple_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
         for i in 0..256u16 {
             let mut bitmap = RoaringBitmap::new();
@@ -129,18 +133,19 @@ mod tests {
         txn.commit().unwrap();
         index
     }
-    fn get_random_looking_index() -> Index<U16Codec> {
-        let index = Index::<U16Codec>::new(4, 8);
+    fn get_random_looking_index() -> FacetIndex<OrderedF64Codec> {
+        let index = FacetIndex::<OrderedF64Codec>::new(4, 8);
         let mut txn = index.env.write_txn().unwrap();
 
-        let rng = fastrand::Rng::with_seed(0);
-        let keys = std::iter::from_fn(|| Some(rng.u32(..256))).take(128).collect::<Vec<u32>>();
+        let rng = rand::rngs::SmallRng::from_seed([0; 32]);
+        let keys =
+            std::iter::from_fn(|| Some(rng.gen_range(0..256))).take(128).collect::<Vec<u32>>();
 
         for (_i, key) in keys.into_iter().enumerate() {
             let mut bitmap = RoaringBitmap::new();
             bitmap.insert(key);
-            bitmap.insert(key + 100);
-            index.insert(&mut txn, 0, &(key as u16), &bitmap);
+            bitmap.insert(key + 100.);
+            index.insert(&mut txn, 0, &(key as f64), &bitmap);
         }
         txn.commit().unwrap();
         index
@@ -161,7 +166,7 @@ mod tests {
             let db = index.db.content.remap_key_type::<FacetKeyCodec<MyByteSlice>>();
             let iter = descending_facet_sort(&txn, &db, 0, candidates);
             for (facet, docids) in iter {
-                let facet = U16Codec::bytes_decode(facet).unwrap();
+                let facet = OrderedF64Codec::bytes_decode(facet).unwrap();
                 results.push_str(&format!("{facet}: {}\n", display_bitmap(&docids)));
             }
             insta::assert_snapshot!(format!("filter_sort_{i}_descending"), results);

milli/src/search/facet/filter.rs

@@ -7,7 +7,6 @@ use either::Either;
 pub use filter_parser::{Condition, Error as FPError, FilterCondition, Span, Token};
 use heed::types::DecodeIgnore;
 use heed::LazyDecode;
-use log::debug;
 use roaring::RoaringBitmap;
 
 // use super::FacetNumberRange;

milli/src/search/facet/incremental_update.rs

@@ -0,0 +1,459 @@
+use crate::heed_codec::facet::new::{
+    FacetGroupValue, FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice,
+};
+use crate::Result;
+use heed::Error;
+use heed::{types::ByteSlice, BytesDecode, RoTxn, RwTxn};
+use roaring::RoaringBitmap;
+
+use super::get_highest_level;
+
+enum InsertionResult {
+    InPlace,
+    Insert,
+}
+enum DeletionResult {
+    InPlace,
+    Reduce { prev: Option<Vec<u8>>, next: Option<Vec<u8>> },
+    Remove { prev: Option<Vec<u8>>, next: Option<Vec<u8>> },
+}
+
+struct IncrementalFacetUpdate<'i> {
+    db: &'i heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
+    group_size: usize,
+    min_level_size: usize,
+    max_group_size: usize,
+}
+impl<'i> IncrementalFacetUpdate<'i> {
+    fn find_insertion_key_value<'a>(
+        &self,
+        field_id: u16,
+        level: u8,
+        search_key: &[u8],
+        txn: &RoTxn,
+    ) -> Result<(FacetKey<Vec<u8>>, FacetGroupValue)> {
+        let mut prefix = vec![];
+        prefix.extend_from_slice(&field_id.to_be_bytes());
+        prefix.push(level);
+        prefix.extend_from_slice(search_key);
+
+        let mut prefix_iter = self
+            .db
+            .as_polymorph()
+            .prefix_iter::<_, MyByteSlice, FacetGroupValueCodec>(txn, &prefix.as_slice())?;
+        if let Some(e) = prefix_iter.next() {
+            let (key_bytes, value) = e?;
+            let key = FacetKeyCodec::<MyByteSlice>::bytes_decode(&key_bytes)
+                .ok_or(heed::Error::Encoding)?;
+            Ok((
+                FacetKeyCodec::<MyByteSlice>::bytes_decode(&key_bytes)
+                    .ok_or(Error::Encoding)?
+                    .into_owned(),
+                value,
+            ))
+        } else {
+            let key = FacetKey { field_id, level, left_bound: search_key };
+            match self.db.get_lower_than(txn, &key)? {
+                Some((key, value)) => {
+                    if key.level != level || key.field_id != field_id {
+                        let mut prefix = vec![];
+                        prefix.extend_from_slice(&field_id.to_be_bytes());
+                        prefix.push(level);
+
+                        let mut iter = self
+                            .db
+                            .as_polymorph()
+                            .prefix_iter::<_, MyByteSlice, FacetGroupValueCodec>(
+                                txn,
+                                &prefix.as_slice(),
+                            )?;
+                        let (key_bytes, value) = iter.next().unwrap()?;
+                        Ok((
+                            FacetKeyCodec::<MyByteSlice>::bytes_decode(&key_bytes)
+                                .ok_or(Error::Encoding)?
+                                .into_owned(),
+                            value,
+                        ))
+                    } else {
+                        Ok((key.into_owned(), value))
+                    }
+                }
+                None => panic!(),
+            }
+        }
+    }
+
+    fn insert_in_level_0<'t>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        new_key: &[u8],
+        new_values: &RoaringBitmap,
+    ) -> Result<InsertionResult> {
+        let key = FacetKey { field_id, level: 0, left_bound: new_key };
+        let value = FacetGroupValue { bitmap: new_values.clone(), size: 1 };
+
+        let mut level0_prefix = vec![];
+        level0_prefix.extend_from_slice(&field_id.to_be_bytes());
+        level0_prefix.push(0);
+
+        let mut iter = self
+            .db
+            .as_polymorph()
+            .prefix_iter::<_, ByteSlice, FacetGroupValueCodec>(&txn, &level0_prefix)?;
+
+        if iter.next().is_none() {
+            drop(iter);
+            self.db.put(txn, &key, &value)?;
+            return Ok(InsertionResult::Insert);
+        } else {
+            drop(iter);
+            let old_value = self.db.get(&txn, &key)?;
+            match old_value {
+                Some(mut updated_value) => {
+                    // now merge the two
+                    updated_value.bitmap |= value.bitmap;
+                    self.db.put(txn, &key, &updated_value)?;
+                    Ok(InsertionResult::InPlace)
+                }
+                None => {
+                    self.db.put(txn, &key, &value)?;
+                    Ok(InsertionResult::Insert)
+                }
+            }
+        }
+    }
+    fn insert_in_level<'t>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        level: u8,
+        new_key: &[u8],
+        new_values: &RoaringBitmap,
+    ) -> Result<InsertionResult> {
+        if level == 0 {
+            return self.insert_in_level_0(txn, field_id, new_key, new_values);
+        }
+
+        let max_group_size = self.max_group_size;
+
+        let (insertion_key, insertion_value) =
+            self.find_insertion_key_value(field_id, level, new_key, txn)?;
+
+        let result = self.insert_in_level(txn, field_id, level - 1, new_key.clone(), new_values)?;
+        // level below inserted an element
+
+        let insertion_key = {
+            let mut new_insertion_key = insertion_key.clone();
+            let mut modified = false;
+
+            if new_key < insertion_key.left_bound.as_slice() {
+                new_insertion_key.left_bound = new_key.to_vec();
+                modified = true;
+            }
+            if modified {
+                let is_deleted = self.db.delete(txn, &insertion_key.as_ref())?;
+                assert!(is_deleted);
+                self.db.put(txn, &new_insertion_key.as_ref(), &insertion_value)?;
+            }
+            new_insertion_key
+        };
+
+        match result {
+            // TODO: this could go above the block recomputing insertion key
+            // because we know that if we inserted in place, the key is not a new one
+            // thus it doesn't extend a group
+            InsertionResult::InPlace => {
+                let mut updated_value = self.db.get(&txn, &insertion_key.as_ref())?.unwrap();
+                updated_value.bitmap |= new_values;
+                self.db.put(txn, &insertion_key.as_ref(), &updated_value)?;
+
+                return Ok(InsertionResult::InPlace);
+            }
+            InsertionResult::Insert => {}
+        }
+        let mut updated_value = self.db.get(&txn, &insertion_key.as_ref())?.unwrap();
+
+        updated_value.size += 1;
+        if updated_value.size as usize == max_group_size {
+            // need to split it
+            // recompute left element and right element
+            // replace current group by left element
+            // add one more group to the right
+
+            let size_left = max_group_size / 2;
+            let size_right = max_group_size - size_left;
+
+            let level_below = level - 1;
+
+            let (start_key, _) = self
+                .db
+                .get_greater_than_or_equal_to(
+                    &txn,
+                    &FacetKey {
+                        field_id,
+                        level: level_below,
+                        left_bound: insertion_key.left_bound.as_slice(),
+                    },
+                )?
+                .unwrap();
+
+            let mut iter = self.db.range(&txn, &(start_key..))?.take(max_group_size);
+
+            let group_left = {
+                let mut values_left = RoaringBitmap::new();
+
+                let mut i = 0;
+                while let Some(next) = iter.next() {
+                    let (_key, value) = next?;
+                    i += 1;
+                    values_left |= &value.bitmap;
+                    if i == size_left {
+                        break;
+                    }
+                }
+
+                let key =
+                    FacetKey { field_id, level, left_bound: insertion_key.left_bound.clone() };
+                let value = FacetGroupValue { size: size_left as u8, bitmap: values_left };
+                (key, value)
+            };
+
+            let group_right = {
+                let mut values_right = RoaringBitmap::new();
+                let mut right_start_key = None;
+
+                while let Some(next) = iter.next() {
+                    let (key, value) = next?;
+                    if right_start_key.is_none() {
+                        right_start_key = Some(key.left_bound);
+                    }
+                    values_right |= &value.bitmap;
+                }
+
+                let key =
+                    FacetKey { field_id, level, left_bound: right_start_key.unwrap().to_vec() };
+                let value = FacetGroupValue { size: size_right as u8, bitmap: values_right };
+                (key, value)
+            };
+            drop(iter);
+
+            let _ = self.db.delete(txn, &insertion_key.as_ref())?;
+
+            self.db.put(txn, &group_left.0.as_ref(), &group_left.1)?;
+            self.db.put(txn, &group_right.0.as_ref(), &group_right.1)?;
+
+            Ok(InsertionResult::Insert)
+        } else {
+            let mut value = self.db.get(&txn, &insertion_key.as_ref())?.unwrap();
+            value.bitmap |= new_values;
+            value.size += 1;
+            self.db.put(txn, &insertion_key.as_ref(), &value).unwrap();
+
+            Ok(InsertionResult::InPlace)
+        }
+    }
+
+    pub fn insert<'a, 't>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        new_key: &[u8],
+        new_values: &RoaringBitmap,
+    ) -> Result<()> {
+        if new_values.is_empty() {
+            return Ok(());
+        }
+        let group_size = self.group_size;
+
+        let highest_level = get_highest_level(&txn, &self.db, field_id)?;
+
+        let result =
+            self.insert_in_level(txn, field_id, highest_level as u8, new_key, new_values)?;
+        match result {
+            InsertionResult::InPlace => return Ok(()),
+            InsertionResult::Insert => {}
+        }
+
+        let mut highest_level_prefix = vec![];
+        highest_level_prefix.extend_from_slice(&field_id.to_be_bytes());
+        highest_level_prefix.push(highest_level);
+
+        let size_highest_level = self
+            .db
+            .as_polymorph()
+            .prefix_iter::<_, ByteSlice, ByteSlice>(&txn, &highest_level_prefix)?
+            .count();
+
+        if size_highest_level < self.min_level_size {
+            return Ok(());
+        }
+
+        let mut groups_iter = self
+            .db
+            .as_polymorph()
+            .prefix_iter::<_, ByteSlice, FacetGroupValueCodec>(&txn, &highest_level_prefix)?;
+
+        let mut to_add = vec![];
+        for _ in 0..group_size {
+            let mut first_key = None;
+            let mut values = RoaringBitmap::new();
+            for _ in 0..group_size {
+                let (key_bytes, value_i) = groups_iter.next().unwrap()?;
+                let key_i = FacetKeyCodec::<MyByteSlice>::bytes_decode(&key_bytes)
+                    .ok_or(Error::Encoding)?;
+
+                if first_key.is_none() {
+                    first_key = Some(key_i);
+                }
+                values |= value_i.bitmap;
+            }
+            let key = FacetKey {
+                field_id,
+                level: highest_level + 1,
+                left_bound: first_key.unwrap().left_bound,
+            };
+            let value = FacetGroupValue { size: group_size as u8, bitmap: values };
+            to_add.push((key.into_owned(), value));
+        }
+        drop(groups_iter);
+        for (key, value) in to_add {
+            self.db.put(txn, &key.as_ref(), &value)?;
+        }
+        Ok(())
+    }
+
+    fn delete_in_level<'t>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        level: u8,
+        key: &[u8],
+        value: u32,
+    ) -> Result<DeletionResult> {
+        if level == 0 {
+            return self.delete_in_level_0(txn, field_id, key, value);
+        }
+        let (deletion_key, mut bitmap) =
+            self.find_insertion_key_value(field_id, level, key, txn)?;
+
+        let result = self.delete_in_level(txn, field_id, level - 1, key.clone(), value)?;
+
+        let mut decrease_size = false;
+        let (prev_key, next_key) = match result {
+            DeletionResult::InPlace => {
+                bitmap.bitmap.remove(value);
+                self.db.put(txn, &deletion_key.as_ref(), &bitmap)?;
+                return Ok(DeletionResult::InPlace);
+            }
+            DeletionResult::Reduce { prev, next } => (prev, next),
+            DeletionResult::Remove { prev, next } => {
+                decrease_size = true;
+                (prev, next)
+            }
+        };
+
+        let mut updated_value = bitmap;
+        if decrease_size {
+            updated_value.size -= 1;
+        }
+
+        if updated_value.size == 0 {
+            self.db.delete(txn, &deletion_key.as_ref())?;
+            Ok(DeletionResult::Remove { prev: prev_key, next: next_key })
+        } else {
+            let mut updated_deletion_key = deletion_key.clone();
+            if key == deletion_key.left_bound {
+                updated_deletion_key.left_bound = next_key.clone().unwrap();
+            }
+            updated_value.bitmap.remove(value);
+            let _ = self.db.delete(txn, &deletion_key.as_ref())?;
+            self.db.put(txn, &updated_deletion_key.as_ref(), &updated_value)?;
+
+            Ok(DeletionResult::Reduce { prev: prev_key, next: next_key })
+        }
+    }
+
+    fn delete_in_level_0<'t>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        key: &[u8],
+        value: u32,
+    ) -> Result<DeletionResult> {
+        let key = FacetKey { field_id, level: 0, left_bound: key };
+        let mut bitmap = self.db.get(&txn, &key)?.unwrap().bitmap;
+        bitmap.remove(value);
+
+        if bitmap.is_empty() {
+            let mut prev_key = None;
+            let mut next_key = None;
+
+            if let Some(prev) = self.db.get_lower_than(&txn, &key)? {
+                prev_key = Some(prev.0.left_bound.to_vec());
+            }
+            if let Some(next) = self.db.get_greater_than(&txn, &key)? {
+                if next.0.level == 0 {
+                    next_key = Some(next.0.left_bound.to_vec());
+                }
+            }
+            self.db.delete(txn, &key)?;
+            Ok(DeletionResult::Remove { prev: prev_key, next: next_key })
+        } else {
+            self.db.put(txn, &key, &FacetGroupValue { size: 1, bitmap })?;
+            Ok(DeletionResult::InPlace)
+        }
+    }
+
+    pub fn delete<'a, 't>(
+        &self,
+        txn: &'t mut RwTxn,
+        field_id: u16,
+        key: &[u8],
+        value: u32,
+    ) -> Result<()> {
+        if self.db.get(txn, &FacetKey { field_id, level: 0, left_bound: key })?.is_none() {
+            return Ok(());
+        }
+        let highest_level = get_highest_level(&txn, &self.db, field_id)?;
+
+        // let key_bytes = BoundCodec::bytes_encode(&key).unwrap();
+
+        let result = self.delete_in_level(txn, field_id, highest_level as u8, key, value)?;
+        match result {
+            DeletionResult::InPlace => return Ok(()),
+            DeletionResult::Reduce { .. } => {}
+            DeletionResult::Remove { .. } => {}
+        }
+        let mut highest_level_prefix = vec![];
+        highest_level_prefix.extend_from_slice(&field_id.to_be_bytes());
+        highest_level_prefix.push(highest_level);
+
+        if highest_level == 0
+            || self
+                .db
+                .as_polymorph()
+                .prefix_iter::<_, ByteSlice, ByteSlice>(&txn, &highest_level_prefix)?
+                .count()
+                >= self.group_size
+        {
+            return Ok(());
+        }
+        let mut to_delete = vec![];
+        let mut iter = self
+            .db
+            .as_polymorph()
+            .prefix_iter::<_, ByteSlice, ByteSlice>(txn, &highest_level_prefix)?;
+        while let Some(el) = iter.next() {
+            let (k, _) = el?;
+            to_delete.push(
+                FacetKeyCodec::<MyByteSlice>::bytes_decode(k).ok_or(Error::Encoding)?.into_owned(),
+            );
+        }
+        drop(iter);
+        for k in to_delete {
+            self.db.delete(txn, &k.as_ref())?;
+        }
+        Ok(())
+    }
+}

milli/src/search/facet/mod.rs

@@ -10,38 +10,39 @@ pub use self::filter::Filter;
 
 mod facet_distribution;
 mod facet_distribution_iter;
+mod facet_range_search;
 mod facet_sort_ascending;
 mod facet_sort_descending;
 mod filter;
+mod incremental_update;
 
-fn get_first_facet_value<'t, BoundCodec>(
+pub(crate) fn get_first_facet_value<'t, BoundCodec>(
     txn: &'t RoTxn,
     db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
     field_id: u16,
-) -> Option<BoundCodec::DItem>
+) -> crate::Result<Option<BoundCodec::DItem>>
 where
     BoundCodec: BytesDecode<'t>,
 {
     let mut level0prefix = vec![];
     level0prefix.extend_from_slice(&field_id.to_be_bytes());
     level0prefix.push(0);
-    let mut level0_iter_forward = db
-        .as_polymorph()
-        .prefix_iter::<_, ByteSlice, ByteSlice>(txn, level0prefix.as_slice())
-        .unwrap();
+    let mut level0_iter_forward =
+        db.as_polymorph().prefix_iter::<_, ByteSlice, ByteSlice>(txn, level0prefix.as_slice())?;
     if let Some(first) = level0_iter_forward.next() {
-        let (first_key, _) = first.unwrap();
-        let first_key = FacetKeyCodec::<BoundCodec>::bytes_decode(first_key).unwrap();
-        Some(first_key.left_bound)
+        let (first_key, _) = first?;
+        let first_key =
+            FacetKeyCodec::<BoundCodec>::bytes_decode(first_key).ok_or(heed::Error::Encoding)?;
+        Ok(Some(first_key.left_bound))
     } else {
-        None
+        Ok(None)
     }
 }
-fn get_last_facet_value<'t, BoundCodec>(
+pub(crate) fn get_last_facet_value<'t, BoundCodec>(
     txn: &'t RoTxn,
     db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
     field_id: u16,
-) -> Option<BoundCodec::DItem>
+) -> crate::Result<Option<BoundCodec::DItem>>
 where
     BoundCodec: BytesDecode<'t>,
 {
@@ -50,30 +51,129 @@ where
     level0prefix.push(0);
     let mut level0_iter_backward = db
         .as_polymorph()
-        .rev_prefix_iter::<_, ByteSlice, ByteSlice>(txn, level0prefix.as_slice())
-        .unwrap();
+        .rev_prefix_iter::<_, ByteSlice, ByteSlice>(txn, level0prefix.as_slice())?;
     if let Some(last) = level0_iter_backward.next() {
-        let (last_key, _) = last.unwrap();
-        let last_key = FacetKeyCodec::<BoundCodec>::bytes_decode(last_key).unwrap();
-        Some(last_key.left_bound)
+        let (last_key, _) = last?;
+        let last_key =
+            FacetKeyCodec::<BoundCodec>::bytes_decode(last_key).ok_or(heed::Error::Encoding)?;
+        Ok(Some(last_key.left_bound))
     } else {
-        None
+        Ok(None)
     }
 }
-fn get_highest_level<'t>(
+pub(crate) fn get_highest_level<'t>(
     txn: &'t RoTxn<'t>,
     db: &'t heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
     field_id: u16,
-) -> u8 {
+) -> crate::Result<u8> {
     let field_id_prefix = &field_id.to_be_bytes();
-    db.as_polymorph()
-        .rev_prefix_iter::<_, ByteSlice, ByteSlice>(&txn, field_id_prefix)
-        .unwrap()
+    Ok(db
+        .as_polymorph()
+        .rev_prefix_iter::<_, ByteSlice, ByteSlice>(&txn, field_id_prefix)?
         .next()
         .map(|el| {
             let (key, _) = el.unwrap();
             let key = FacetKeyCodec::<MyByteSlice>::bytes_decode(key).unwrap();
             key.level
         })
-        .unwrap_or(0)
+        .unwrap_or(0))
+}
+
+#[cfg(test)]
+mod test {
+    use std::{fmt::Display, marker::PhantomData, rc::Rc};
+
+    use heed::{BytesDecode, BytesEncode, Env};
+    use tempfile::TempDir;
+
+    use crate::{
+        heed_codec::facet::new::{
+            FacetGroupValue, FacetGroupValueCodec, FacetKey, FacetKeyCodec, MyByteSlice,
+        },
+        snapshot_tests::display_bitmap,
+    };
+
+    pub struct FacetIndex<BoundCodec>
+    where
+        for<'a> BoundCodec:
+            BytesEncode<'a> + BytesDecode<'a, DItem = <BoundCodec as BytesEncode<'a>>::EItem>,
+    {
+        pub env: Env,
+        pub db: Database,
+        _phantom: PhantomData<BoundCodec>,
+    }
+
+    pub struct Database {
+        pub content: heed::Database<FacetKeyCodec<MyByteSlice>, FacetGroupValueCodec>,
+        pub group_size: usize,
+        pub max_group_size: usize,
+        _tempdir: Rc<tempfile::TempDir>,
+    }
+
+    impl<BoundCodec> FacetIndex<BoundCodec>
+    where
+        for<'a> BoundCodec:
+            BytesEncode<'a> + BytesDecode<'a, DItem = <BoundCodec as BytesEncode<'a>>::EItem>,
+    {
+        pub fn open_from_tempdir(
+            tempdir: Rc<TempDir>,
+            group_size: u8,
+            max_group_size: u8,
+        ) -> FacetIndex<BoundCodec> {
+            let group_size = std::cmp::min(127, std::cmp::max(group_size, 2)) as usize;
+            let max_group_size = std::cmp::max(group_size * 2, max_group_size as usize);
+            let mut options = heed::EnvOpenOptions::new();
+            let options = options.map_size(4096 * 4 * 10 * 100);
+            unsafe {
+                options.flag(heed::flags::Flags::MdbAlwaysFreePages);
+            }
+            let env = options.open(tempdir.path()).unwrap();
+            let content = env.open_database(None).unwrap().unwrap();
+
+            FacetIndex {
+                db: Database { content, group_size, max_group_size, _tempdir: tempdir },
+                env,
+                _phantom: PhantomData,
+            }
+        }
+        pub fn new(group_size: u8, max_group_size: u8) -> FacetIndex<BoundCodec> {
+            let group_size = std::cmp::min(127, std::cmp::max(group_size, 2)) as usize;
+            let max_group_size = std::cmp::max(group_size * 2, max_group_size as usize);
+            let mut options = heed::EnvOpenOptions::new();
+            let options = options.map_size(4096 * 4 * 100);
+            let tempdir = tempfile::TempDir::new_in("databases/").unwrap();
+            let env = options.open(tempdir.path()).unwrap();
+            let content = env.create_database(None).unwrap();
+
+            FacetIndex {
+                db: Database { content, group_size, max_group_size, _tempdir: Rc::new(tempdir) },
+                env,
+                _phantom: PhantomData,
+            }
+        }
+    }
+
+    impl<BoundCodec> Display for FacetIndex<BoundCodec>
+    where
+        for<'a> <BoundCodec as BytesEncode<'a>>::EItem: Sized + Display,
+        for<'a> BoundCodec:
+            BytesEncode<'a> + BytesDecode<'a, DItem = <BoundCodec as BytesEncode<'a>>::EItem>,
+    {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            let txn = self.env.read_txn().unwrap();
+            let mut iter = self.db.content.iter(&txn).unwrap();
+            while let Some(el) = iter.next() {
+                let (key, value) = el.unwrap();
+                let FacetKey { field_id, level, left_bound: bound } = key;
+                let bound = BoundCodec::bytes_decode(bound).unwrap();
+                let FacetGroupValue { size, bitmap } = value;
+                writeln!(
+                    f,
+                    "{field_id:<2} {level:<2} k{bound:<8} {size:<4} {values:?}",
+                    values = display_bitmap(&bitmap)
+                )?;
+            }
+            Ok(())
+        }
+    }
 }