diff --git a/milli/Cargo.toml b/milli/Cargo.toml
index edcec4d5b..8616dcf4a 100644
--- a/milli/Cargo.toml
+++ b/milli/Cargo.toml
@@ -6,7 +6,6 @@ edition = "2018"
 
 [dependencies]
 bstr = "0.2.15"
-byte-unit = { version = "4.0.9", default-features = false, features = ["std"] }
 byteorder = "1.4.2"
 chrono = { version = "0.4.19", features = ["serde"] }
 concat-arrays = "0.1.2"
diff --git a/milli/src/heed_codec/facet/facet_string_level_zero_value_codec.rs b/milli/src/heed_codec/facet/facet_string_level_zero_value_codec.rs
index 914d7c3cd..22031c474 100644
--- a/milli/src/heed_codec/facet/facet_string_level_zero_value_codec.rs
+++ b/milli/src/heed_codec/facet/facet_string_level_zero_value_codec.rs
@@ -5,6 +5,7 @@ use std::{marker, str};
 use crate::error::SerializationError;
 use crate::heed_codec::RoaringBitmapCodec;
 use crate::{try_split_array_at, try_split_at, Result};
+
 pub type FacetStringLevelZeroValueCodec = StringValueCodec<RoaringBitmapCodec>;
 
 /// A codec that encodes a string in front of a value.
@@ -22,7 +23,6 @@ where
 
     fn bytes_decode(bytes: &'a [u8]) -> Option<Self::DItem> {
         let (string, bytes) = decode_prefix_string(bytes)?;
-
         C::bytes_decode(bytes).map(|item| (string, item))
     }
 }
@@ -49,7 +49,6 @@ pub fn decode_prefix_string(value: &[u8]) -> Option<(&str, &[u8])> {
     let original_length = u16::from_be_bytes(original_length_bytes) as usize;
     let (string, bytes) = try_split_at(bytes, original_length)?;
     let string = str::from_utf8(string).ok()?;
-
     Some((string, bytes))
 }
 
diff --git a/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs b/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
index c0e984d44..519997274 100644
--- a/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
+++ b/milli/src/heed_codec/roaring_bitmap/cbo_roaring_bitmap_codec.rs
@@ -55,9 +55,9 @@ impl CboRoaringBitmapCodec {
 
     /// Merge serialized CboRoaringBitmaps in a buffer.
     ///
-    /// if the merged values len is under the threshold,
-    /// values are directly serialized in the buffer;
-    /// else a RoaringBitmap is created from the values and is serialized in the buffer.
+    /// if the merged values length is under the threshold, values are directly
+    /// serialized in the buffer else a RoaringBitmap is created from the
+    /// values and is serialized in the buffer.
     pub fn merge_into(slices: &[Cow<[u8]>], buffer: &mut Vec<u8>) -> io::Result<()> {
         let mut roaring = RoaringBitmap::new();
         let mut vec = Vec::new();
diff --git a/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs b/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
index c46329f61..a1bf0b1e3 100644
--- a/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
+++ b/milli/src/update/index_documents/extract/extract_fid_docid_facet_values.rs
@@ -58,11 +58,12 @@ pub fn extract_fid_docid_facet_values<R: io::Read>(
                 // insert facet numbers in sorter
                 for number in numbers {
                     key_buffer.truncate(size_of::<FieldId>() + size_of::<DocumentId>());
-                    let value_bytes = f64_into_bytes(number).unwrap(); // invalid float
-                    key_buffer.extend_from_slice(&value_bytes);
-                    key_buffer.extend_from_slice(&number.to_be_bytes());
+                    if let Some(value_bytes) = f64_into_bytes(number) {
+                        key_buffer.extend_from_slice(&value_bytes);
+                        key_buffer.extend_from_slice(&number.to_be_bytes());
 
-                    fid_docid_facet_numbers_sorter.insert(&key_buffer, ().as_bytes())?;
+                        fid_docid_facet_numbers_sorter.insert(&key_buffer, ().as_bytes())?;
+                    }
                 }
 
                 // insert  normalized and original facet string in sorter
diff --git a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
index cf698507d..1fbc55714 100644
--- a/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_fid_word_count_docids.rs
@@ -8,6 +8,8 @@ use super::helpers::{
     create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
     try_split_array_at, GrenadParameters, MergeFn,
 };
+use crate::error::SerializationError;
+use crate::index::db_name::DOCID_WORD_POSITIONS;
 use crate::proximity::extract_position;
 use crate::{DocumentId, FieldId, Result};
 
@@ -36,7 +38,8 @@ pub fn extract_fid_word_count_docids<R: io::Read>(
     let mut current_document_id = None;
 
     while let Some((key, value)) = docid_word_positions.next()? {
-        let (document_id_bytes, _word_bytes) = try_split_array_at(key).unwrap();
+        let (document_id_bytes, _word_bytes) = try_split_array_at(key)
+            .ok_or_else(|| SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
 
         let curr_document_id = *current_document_id.get_or_insert(document_id);
diff --git a/milli/src/update/index_documents/extract/extract_word_docids.rs b/milli/src/update/index_documents/extract/extract_word_docids.rs
index 8ca8e39eb..6d99fda44 100644
--- a/milli/src/update/index_documents/extract/extract_word_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_docids.rs
@@ -8,6 +8,8 @@ use super::helpers::{
     create_sorter, merge_roaring_bitmaps, serialize_roaring_bitmap, sorter_into_reader,
     try_split_array_at, GrenadParameters,
 };
+use crate::error::SerializationError;
+use crate::index::db_name::DOCID_WORD_POSITIONS;
 use crate::Result;
 
 /// Extracts the word and the documents ids where this word appear.
@@ -31,7 +33,8 @@ pub fn extract_word_docids<R: io::Read>(
 
     let mut value_buffer = Vec::new();
     while let Some((key, _value)) = docid_word_positions.next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key).unwrap();
+        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+            .ok_or_else(|| SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
 
         let bitmap = RoaringBitmap::from_iter(Some(document_id));
diff --git a/milli/src/update/index_documents/extract/extract_word_level_position_docids.rs b/milli/src/update/index_documents/extract/extract_word_level_position_docids.rs
index e099b0b49..04cedf5c7 100644
--- a/milli/src/update/index_documents/extract/extract_word_level_position_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_level_position_docids.rs
@@ -5,7 +5,10 @@ use super::helpers::{
     create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
     try_split_array_at, GrenadParameters,
 };
+use crate::error::SerializationError;
+use crate::index::db_name::DOCID_WORD_POSITIONS;
 use crate::{DocumentId, Result};
+
 /// Extracts the word positions and the documents ids where this word appear.
 ///
 /// Returns a grenad reader with the list of extracted words at positions and
@@ -27,7 +30,8 @@ pub fn extract_word_level_position_docids<R: io::Read>(
 
     let mut key_buffer = Vec::new();
     while let Some((key, value)) = docid_word_positions.next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key).unwrap();
+        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+            .ok_or_else(|| SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = DocumentId::from_be_bytes(document_id_bytes);
 
         for position in read_u32_ne_bytes(value) {
diff --git a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
index ce75c319e..982799a65 100644
--- a/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
+++ b/milli/src/update/index_documents/extract/extract_word_pair_proximity_docids.rs
@@ -1,15 +1,14 @@
 use std::cmp::Ordering;
 use std::collections::{BinaryHeap, HashMap};
 use std::fs::File;
-use std::time::{Duration, Instant};
 use std::{cmp, io, mem, str, vec};
 
-use log::debug;
-
 use super::helpers::{
     create_sorter, merge_cbo_roaring_bitmaps, read_u32_ne_bytes, sorter_into_reader,
     try_split_array_at, GrenadParameters, MergeFn,
 };
+use crate::error::SerializationError;
+use crate::index::db_name::DOCID_WORD_POSITIONS;
 use crate::proximity::{positions_proximity, MAX_DISTANCE};
 use crate::{DocumentId, Result};
 
@@ -32,16 +31,13 @@ pub fn extract_word_pair_proximity_docids<R: io::Read>(
         max_memory.map(|m| m / 2),
     );
 
-    let mut number_of_documents = 0;
-    let mut total_time_aggregation = Duration::default();
-    let mut total_time_grenad_insert = Duration::default();
-
     // This map is assumed to not consume a lot of memory.
     let mut document_word_positions_heap = BinaryHeap::new();
     let mut current_document_id = None;
 
     while let Some((key, value)) = docid_word_positions.next()? {
-        let (document_id_bytes, word_bytes) = try_split_array_at(key).unwrap();
+        let (document_id_bytes, word_bytes) = try_split_array_at(key)
+            .ok_or_else(|| SerializationError::Decoding { db_name: Some(DOCID_WORD_POSITIONS) })?;
         let document_id = u32::from_be_bytes(document_id_bytes);
         let word = str::from_utf8(word_bytes)?;
 
@@ -52,10 +48,7 @@ pub fn extract_word_pair_proximity_docids<R: io::Read>(
                 curr_document_id,
                 document_word_positions_heap,
                 &mut word_pair_proximity_docids_sorter,
-                &mut total_time_aggregation,
-                &mut total_time_grenad_insert,
             )?;
-            number_of_documents += 1;
             current_document_id = Some(document_id);
         }
 
@@ -74,18 +67,9 @@ pub fn extract_word_pair_proximity_docids<R: io::Read>(
             document_id,
             document_word_positions_heap,
             &mut word_pair_proximity_docids_sorter,
-            &mut total_time_aggregation,
-            &mut total_time_grenad_insert,
         )?;
     }
 
-    debug!(
-        "Number of documents {}
-        - we took {:02?} to aggregate proximities
-        - we took {:02?} to grenad insert those proximities",
-        number_of_documents, total_time_aggregation, total_time_grenad_insert,
-    );
-
     sorter_into_reader(word_pair_proximity_docids_sorter, indexer)
 }
 
@@ -97,10 +81,7 @@ fn document_word_positions_into_sorter<'b>(
     document_id: DocumentId,
     mut word_positions_heap: BinaryHeap<PeekedWordPosition<vec::IntoIter<u32>>>,
     word_pair_proximity_docids_sorter: &mut grenad::Sorter<MergeFn>,
-    total_time_aggregation: &mut Duration,
-    total_time_grenad_insert: &mut Duration,
 ) -> Result<()> {
-    let before_aggregating = Instant::now();
     let mut word_pair_proximity = HashMap::new();
     let mut ordered_peeked_word_positions = Vec::new();
     while !word_positions_heap.is_empty() {
@@ -152,8 +133,6 @@ fn document_word_positions_into_sorter<'b>(
         }
     }
 
-    *total_time_aggregation += before_aggregating.elapsed();
-
     let mut key_buffer = Vec::new();
     for ((w1, w2), prox) in word_pair_proximity {
         key_buffer.clear();
@@ -162,9 +141,7 @@ fn document_word_positions_into_sorter<'b>(
         key_buffer.extend_from_slice(w2.as_bytes());
         key_buffer.push(prox as u8);
 
-        let before_grenad_insert = Instant::now();
         word_pair_proximity_docids_sorter.insert(&key_buffer, &document_id.to_ne_bytes())?;
-        *total_time_grenad_insert += before_grenad_insert.elapsed();
     }
 
     Ok(())
diff --git a/milli/src/update/index_documents/extract/mod.rs b/milli/src/update/index_documents/extract/mod.rs
index 04c57b0fa..bb49e3e51 100644
--- a/milli/src/update/index_documents/extract/mod.rs
+++ b/milli/src/update/index_documents/extract/mod.rs
@@ -225,5 +225,6 @@ fn extract_documents_data(
                 Ok((docid_fid_facet_numbers_chunk, docid_fid_facet_strings_chunk))
             },
         );
+
     Ok((docid_word_positions_chunk?, docid_fid_facet_values_chunks?))
 }
diff --git a/milli/src/update/index_documents/helpers/clonable_mmap.rs b/milli/src/update/index_documents/helpers/clonable_mmap.rs
index b16c080ff..691d10593 100644
--- a/milli/src/update/index_documents/helpers/clonable_mmap.rs
+++ b/milli/src/update/index_documents/helpers/clonable_mmap.rs
@@ -2,6 +2,8 @@ use std::sync::Arc;
 
 use memmap::Mmap;
 
+/// Wrapper around Mmap allowing to virtualy clone grenad-chunks
+/// in a parallel process like the indexing.
 #[derive(Debug, Clone)]
 pub struct ClonableMmap {
     inner: Arc<Mmap>,
diff --git a/milli/src/update/index_documents/helpers/grenad_helpers.rs b/milli/src/update/index_documents/helpers/grenad_helpers.rs
index 9dd261f73..1dfaaf945 100644
--- a/milli/src/update/index_documents/helpers/grenad_helpers.rs
+++ b/milli/src/update/index_documents/helpers/grenad_helpers.rs
@@ -3,7 +3,6 @@ use std::fs::File;
 use std::io::{self, Seek, SeekFrom};
 use std::time::Instant;
 
-use byte_unit::Byte;
 use grenad::{CompressionType, MergerIter, Reader, Sorter};
 use heed::types::ByteSlice;
 use log::debug;
@@ -113,6 +112,9 @@ impl Default for GrenadParameters {
 }
 
 impl GrenadParameters {
+    /// This function use the number of threads in the current threadpool to compute the value.
+    /// This should be called inside of a rayon thread pool,
+    /// Otherwise, it will take the global number of threads.
     pub fn max_memory_by_thread(&self) -> Option<usize> {
         self.max_memory.map(|max_memory| max_memory / rayon::current_num_threads())
     }
@@ -128,7 +130,7 @@ pub fn grenad_obkv_into_chunks<R: io::Read>(
     mut reader: grenad::Reader<R>,
     indexer: GrenadParameters,
     log_frequency: Option<usize>,
-    documents_chunk_size: Byte,
+    documents_chunk_size: usize,
 ) -> Result<impl Iterator<Item = Result<grenad::Reader<File>>>> {
     let mut document_count = 0;
     let mut continue_reading = true;
@@ -157,7 +159,7 @@ pub fn grenad_obkv_into_chunks<R: io::Read>(
                 debug!("reached {} chunked documents", document_count);
             }
 
-            if current_chunk_size >= documents_chunk_size.get_bytes() {
+            if current_chunk_size >= documents_chunk_size as u64 {
                 return writer_into_reader(obkv_documents).map(Some);
             }
         }
@@ -170,8 +172,8 @@ pub fn grenad_obkv_into_chunks<R: io::Read>(
         let result = transposer().transpose();
         if result.as_ref().map_or(false, |r| r.is_ok()) {
             debug!(
-                "A new chunk of approximately {} has been generated",
-                documents_chunk_size.get_appropriate_unit(true),
+                "A new chunk of approximately {:.2} MiB has been generated",
+                documents_chunk_size as f64 / 1024.0 / 1024.0,
             );
         }
         result
diff --git a/milli/src/update/index_documents/helpers/mod.rs b/milli/src/update/index_documents/helpers/mod.rs
index baacb0a1b..3f38d4f25 100644
--- a/milli/src/update/index_documents/helpers/mod.rs
+++ b/milli/src/update/index_documents/helpers/mod.rs
@@ -40,10 +40,6 @@ where
     Some((head, tail))
 }
 
-// pub fn pretty_thousands<A: Borrow<T>, T: fmt::Display>(number: A) -> String {
-//     thousands::Separable::separate_with_spaces(number.borrow())
-// }
-
 pub fn read_u32_ne_bytes(bytes: &[u8]) -> impl Iterator<Item = u32> + '_ {
     bytes.chunks_exact(4).flat_map(TryInto::try_into).map(u32::from_ne_bytes)
 }
diff --git a/milli/src/update/index_documents/mod.rs b/milli/src/update/index_documents/mod.rs
index 98b0aa80e..b27f2042f 100644
--- a/milli/src/update/index_documents/mod.rs
+++ b/milli/src/update/index_documents/mod.rs
@@ -9,7 +9,6 @@ use std::iter::FromIterator;
 use std::num::{NonZeroU32, NonZeroUsize};
 use std::time::Instant;
 
-use byte_unit::Byte;
 use chrono::Utc;
 use crossbeam_channel::{Receiver, Sender};
 use grenad::{self, CompressionType};
@@ -252,7 +251,7 @@ impl<'t, 'u, 'i, 'a> IndexDocuments<'t, 'u, 'i, 'a> {
                 documents_file,
                 params.clone(),
                 self.log_every_n,
-                Byte::from_bytes(self.documents_chunk_size.unwrap_or(1024 * 1024 * 128) as u64), // 128MiB
+                self.documents_chunk_size.unwrap_or(1024 * 1024 * 128), // 128MiB
             );
 
             let result = chunk_iter.map(|chunk_iter| {
diff --git a/milli/src/update/index_documents/typed_chunk.rs b/milli/src/update/index_documents/typed_chunk.rs
index c3c71bbf4..5f28034fe 100644
--- a/milli/src/update/index_documents/typed_chunk.rs
+++ b/milli/src/update/index_documents/typed_chunk.rs
@@ -1,3 +1,4 @@
+use std::borrow::Cow;
 use std::fs::File;
 
 use heed::types::ByteSlice;
@@ -188,8 +189,6 @@ fn merge_roaring_bitmaps(new_value: &[u8], db_value: &[u8], buffer: &mut Vec<u8>
     Ok(serialize_roaring_bitmap(&value, buffer)?)
 }
 
-use std::borrow::Cow;
-
 fn merge_cbo_roaring_bitmaps(
     new_value: &[u8],
     db_value: &[u8],
@@ -199,11 +198,6 @@ fn merge_cbo_roaring_bitmaps(
         &[Cow::Borrowed(db_value), Cow::Borrowed(new_value)],
         buffer,
     )?)
-
-    // let new_value = CboRoaringBitmapCodec::deserialize_from(new_value)?;
-    // let db_value = CboRoaringBitmapCodec::deserialize_from(db_value)?;
-    // let value = new_value | db_value;
-    // Ok(CboRoaringBitmapCodec::serialize_into(&value, buffer))
 }
 
 /// Write provided entries in database using serialize_value function.