MeiliSearch/milli/src/update/index_documents/mod.rs

mod enrich;
mod extract;
mod helpers;
mod transform;
mod typed_chunk;

use std::collections::HashSet;
use std::io::{Cursor, Read, Seek};
use std::iter::FromIterator;
use std::num::NonZeroU32;
use std::result::Result as StdResult;

use crossbeam_channel::{Receiver, Sender};
use heed::types::Str;
use heed::Database;
use log::debug;
use roaring::RoaringBitmap;
use serde::{Deserialize, Serialize};
use slice_group_by::GroupBy;
use typed_chunk::{write_typed_chunk_into_index, TypedChunk};

use self::enrich::enrich_documents_batch;
pub use self::enrich::{
    extract_finite_float_from_value, validate_document_id, validate_document_id_value,
    validate_geo_from_json, DocumentId,
};
pub use self::helpers::{
    as_cloneable_grenad, create_sorter, create_writer, fst_stream_into_hashset,
    fst_stream_into_vec, merge_btreeset_string, merge_cbo_roaring_bitmaps, merge_roaring_bitmaps,
    sorter_into_lmdb_database, valid_lmdb_key, writer_into_reader, ClonableMmap, MergeFn,
};
use self::helpers::{grenad_obkv_into_chunks, GrenadParameters};
pub use self::transform::{Transform, TransformOutput};
use crate::documents::{obkv_to_object, DocumentsBatchReader};
use crate::error::{Error, InternalError, UserError};
pub use crate::update::index_documents::helpers::CursorClonableMmap;
use crate::update::{
    self, DeletionStrategy, IndexerConfig, PrefixWordPairsProximityDocids, UpdateIndexingStep,
    WordPrefixDocids, WordPrefixIntegerDocids, WordsPrefixesFst,
};
use crate::{Index, Result, RoaringBitmapCodec};

static MERGED_DATABASE_COUNT: usize = 7;
static PREFIX_DATABASE_COUNT: usize = 5;
static TOTAL_POSTING_DATABASE_COUNT: usize = MERGED_DATABASE_COUNT + PREFIX_DATABASE_COUNT;

#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub struct DocumentAdditionResult {
    /// The number of documents that were indexed during the update
    pub indexed_documents: u64,
    /// The total number of documents in the index after the update
    pub number_of_documents: u64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
#[non_exhaustive]
pub enum IndexDocumentsMethod {
    /// Replace the previous document with the new one,
    /// removing all the already known attributes.
    ReplaceDocuments,

    /// Merge the previous version of the document with the new version,
    /// replacing old attributes values with the new ones and add the new attributes.
    UpdateDocuments,
}

impl Default for IndexDocumentsMethod {
    fn default() -> Self {
        Self::ReplaceDocuments
    }
}

pub struct IndexDocuments<'t, 'u, 'i, 'a, FP, FA> {
    wtxn: &'t mut heed::RwTxn<'i, 'u>,
    index: &'i Index,
    config: IndexDocumentsConfig,
    indexer_config: &'a IndexerConfig,
    transform: Option<Transform<'a, 'i>>,
    progress: FP,
    should_abort: FA,
    added_documents: u64,
    deleted_documents: u64,
}

#[derive(Default, Debug, Clone)]
pub struct IndexDocumentsConfig {
    pub words_prefix_threshold: Option<u32>,
    pub max_prefix_length: Option<usize>,
    pub words_positions_level_group_size: Option<NonZeroU32>,
    pub words_positions_min_level_size: Option<NonZeroU32>,
    pub update_method: IndexDocumentsMethod,
    pub deletion_strategy: DeletionStrategy,
    pub autogenerate_docids: bool,
}

impl<'t, 'u, 'i, 'a, FP, FA> IndexDocuments<'t, 'u, 'i, 'a, FP, FA>
where
    FP: Fn(UpdateIndexingStep) + Sync,
    FA: Fn() -> bool + Sync,
{
    pub fn new(
        wtxn: &'t mut heed::RwTxn<'i, 'u>,
        index: &'i Index,
        indexer_config: &'a IndexerConfig,
        config: IndexDocumentsConfig,
        progress: FP,
        should_abort: FA,
    ) -> Result<IndexDocuments<'t, 'u, 'i, 'a, FP, FA>> {
        let transform = Some(Transform::new(
            wtxn,
            index,
            indexer_config,
            config.update_method,
            config.autogenerate_docids,
        )?);

        Ok(IndexDocuments {
            transform,
            config,
            indexer_config,
            progress,
            should_abort,
            wtxn,
            index,
            added_documents: 0,
            deleted_documents: 0,
        })
    }

    /// Adds a batch of documents to the current builder.
    ///
    /// Since the documents are progressively added to the writer, a failure will cause only
    /// return an error and not the `IndexDocuments` struct as it is invalid to use it afterward.
    ///
    /// Returns the number of documents added to the builder.
    pub fn add_documents<R: Read + Seek>(
        mut self,
        reader: DocumentsBatchReader<R>,
    ) -> Result<(Self, StdResult<u64, UserError>)> {
        puffin::profile_function!();

        // Early return when there is no document to add
        if reader.is_empty() {
            return Ok((self, Ok(0)));
        }

        // We check for user errors in this validator and if there is one, we can return
        // the `IndexDocument` struct as it is valid to send more documents into it.
        // However, if there is an internal error we throw it away!
        let enriched_documents_reader = match enrich_documents_batch(
            self.wtxn,
            self.index,
            self.config.autogenerate_docids,
            reader,
        )? {
            Ok(reader) => reader,
            Err(user_error) => return Ok((self, Err(user_error))),
        };

        let indexed_documents =
            self.transform.as_mut().expect("Invalid document addition state").read_documents(
                enriched_documents_reader,
                self.wtxn,
                &self.progress,
                &self.should_abort,
            )? as u64;

        self.added_documents += indexed_documents;

        Ok((self, Ok(indexed_documents)))
    }

    /// Remove a batch of documents from the current builder.
    ///
    /// Returns the number of documents deleted from the builder.
    pub fn remove_documents(
        mut self,
        to_delete: Vec<String>,
    ) -> Result<(Self, StdResult<u64, UserError>)> {
        puffin::profile_function!();

        // Early return when there is no document to add
        if to_delete.is_empty() {
            return Ok((self, Ok(0)));
        }

        let deleted_documents = self
            .transform
            .as_mut()
            .expect("Invalid document deletion state")
            .remove_documents(to_delete, self.wtxn, &self.should_abort)?
            as u64;

        self.deleted_documents += deleted_documents;

        Ok((self, Ok(deleted_documents)))
    }

    #[logging_timer::time("IndexDocuments::{}")]
    pub fn execute(mut self) -> Result<DocumentAdditionResult> {
        puffin::profile_function!();

        if self.added_documents == 0 {
            let number_of_documents = self.index.number_of_documents(self.wtxn)?;
            return Ok(DocumentAdditionResult { indexed_documents: 0, number_of_documents });
        }
        let output = self
            .transform
            .take()
            .expect("Invalid document addition state")
            .output_from_sorter(self.wtxn, &self.progress)?;

        let new_facets = output.compute_real_facets(self.wtxn, self.index)?;
        self.index.put_faceted_fields(self.wtxn, &new_facets)?;

        // in case new fields were introduced we're going to recreate the searchable fields.
        if let Some(faceted_fields) = self.index.user_defined_searchable_fields(self.wtxn)? {
            // we can't keep references on the faceted fields while we update the index thus we need to own it.
            let faceted_fields: Vec<String> =
                faceted_fields.into_iter().map(str::to_string).collect();
            self.index.put_all_searchable_fields_from_fields_ids_map(
                self.wtxn,
                &faceted_fields.iter().map(String::as_ref).collect::<Vec<_>>(),
                &output.fields_ids_map,
            )?;
        }

        let indexed_documents = output.documents_count as u64;
        let number_of_documents = self.execute_raw(output)?;

        Ok(DocumentAdditionResult { indexed_documents, number_of_documents })
    }

    /// Returns the total number of documents in the index after the update.
    #[logging_timer::time("IndexDocuments::{}")]
    pub fn execute_raw(self, output: TransformOutput) -> Result<u64>
    where
        FP: Fn(UpdateIndexingStep) + Sync,
        FA: Fn() -> bool + Sync,
    {
        puffin::profile_function!();

        let TransformOutput {
            primary_key,
            fields_ids_map,
            field_distribution,
            new_external_documents_ids,
            new_documents_ids,
            replaced_documents_ids,
            documents_count,
            original_documents,
            flattened_documents,
        } = output;

        // The fields_ids_map is put back to the store now so the rest of the transaction sees an
        // up to date field map.
        self.index.put_fields_ids_map(self.wtxn, &fields_ids_map)?;

        let backup_pool;
        let pool = match self.indexer_config.thread_pool {
            Some(ref pool) => pool,
            #[cfg(not(test))]
            None => {
                // We initialize a bakcup pool with the default
                // settings if none have already been set.
                backup_pool = rayon::ThreadPoolBuilder::new().build()?;
                &backup_pool
            }
            #[cfg(test)]
            None => {
                // We initialize a bakcup pool with the default
                // settings if none have already been set.
                backup_pool = rayon::ThreadPoolBuilder::new().num_threads(1).build()?;
                &backup_pool
            }
        };

        let original_documents = grenad::Reader::new(original_documents)?;
        let flattened_documents = grenad::Reader::new(flattened_documents)?;

        // create LMDB writer channel
        let (lmdb_writer_sx, lmdb_writer_rx): (
            Sender<Result<TypedChunk>>,
            Receiver<Result<TypedChunk>>,
        ) = crossbeam_channel::unbounded();

        // get the primary key field id
        let primary_key_id = fields_ids_map.id(&primary_key).unwrap();

        // get searchable fields for word databases
        let searchable_fields =
            self.index.searchable_fields_ids(self.wtxn)?.map(HashSet::from_iter);
        // get filterable fields for facet databases
        let faceted_fields = self.index.faceted_fields_ids(self.wtxn)?;
        // get the fid of the `_geo.lat` and `_geo.lng` fields.
        let geo_fields_ids = match self.index.fields_ids_map(self.wtxn)?.id("_geo") {
            Some(gfid) => {
                let is_sortable = self.index.sortable_fields_ids(self.wtxn)?.contains(&gfid);
                let is_filterable = self.index.filterable_fields_ids(self.wtxn)?.contains(&gfid);
                // if `_geo` is faceted then we get the `lat` and `lng`
                if is_sortable || is_filterable {
                    let field_ids = self
                        .index
                        .fields_ids_map(self.wtxn)?
                        .insert("_geo.lat")
                        .zip(self.index.fields_ids_map(self.wtxn)?.insert("_geo.lng"))
                        .ok_or(UserError::AttributeLimitReached)?;
                    Some(field_ids)
                } else {
                    None
                }
            }
            None => None,
        };
        // get the fid of the `_vectors` field.
        let vectors_field_id = self.index.fields_ids_map(self.wtxn)?.id("_vectors");

        let stop_words = self.index.stop_words(self.wtxn)?;
        let separators = self.index.allowed_separators(self.wtxn)?;
        let separators: Option<Vec<_>> =
            separators.as_ref().map(|x| x.iter().map(String::as_str).collect());
        let dictionary = self.index.dictionary(self.wtxn)?;
        let dictionary: Option<Vec<_>> =
            dictionary.as_ref().map(|x| x.iter().map(String::as_str).collect());
        let exact_attributes = self.index.exact_attributes_ids(self.wtxn)?;

        let pool_params = GrenadParameters {
            chunk_compression_type: self.indexer_config.chunk_compression_type,
            chunk_compression_level: self.indexer_config.chunk_compression_level,
            max_memory: self.indexer_config.max_memory,
            max_nb_chunks: self.indexer_config.max_nb_chunks, // default value, may be chosen.
        };
        let documents_chunk_size =
            self.indexer_config.documents_chunk_size.unwrap_or(1024 * 1024 * 4); // 4MiB
        let max_positions_per_attributes = self.indexer_config.max_positions_per_attributes;

        // Run extraction pipeline in parallel.
        pool.install(|| {
            puffin::profile_scope!("extract_and_send_grenad_chunks");
            // split obkv file into several chunks
            let original_chunk_iter =
                grenad_obkv_into_chunks(original_documents, pool_params, documents_chunk_size);

            // split obkv file into several chunks
            let flattened_chunk_iter =
                grenad_obkv_into_chunks(flattened_documents, pool_params, documents_chunk_size);

            let result = original_chunk_iter.and_then(|original_chunk| {
                let flattened_chunk = flattened_chunk_iter?;
                // extract all databases from the chunked obkv douments
                extract::data_from_obkv_documents(
                    original_chunk,
                    flattened_chunk,
                    pool_params,
                    lmdb_writer_sx.clone(),
                    searchable_fields,
                    faceted_fields,
                    primary_key_id,
                    geo_fields_ids,
                    vectors_field_id,
                    stop_words,
                    separators.as_deref(),
                    dictionary.as_deref(),
                    max_positions_per_attributes,
                    exact_attributes,
                )
            });

            if let Err(e) = result {
                let _ = lmdb_writer_sx.send(Err(e));
            }

            // needs to be droped to avoid channel waiting lock.
            drop(lmdb_writer_sx)
        });

        // We delete the documents that this document addition replaces. This way we are
        // able to simply insert all the documents even if they already exist in the database.
        if !replaced_documents_ids.is_empty() {
            let mut deletion_builder = update::DeleteDocuments::new(self.wtxn, self.index)?;
            deletion_builder.strategy(self.config.deletion_strategy);
            debug!("documents to delete {:?}", replaced_documents_ids);
            deletion_builder.delete_documents(&replaced_documents_ids);
            let deleted_documents_result = deletion_builder.execute_inner()?;
            debug!("{} documents actually deleted", deleted_documents_result.deleted_documents);
        }

        let index_documents_ids = self.index.documents_ids(self.wtxn)?;
        let index_is_empty = index_documents_ids.is_empty();
        let mut final_documents_ids = RoaringBitmap::new();
        let mut word_pair_proximity_docids = None;
        let mut word_position_docids = None;
        let mut word_fid_docids = None;
        let mut word_docids = None;
        let mut exact_word_docids = None;

        let mut databases_seen = 0;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        for result in lmdb_writer_rx {
            if (self.should_abort)() {
                return Err(Error::InternalError(InternalError::AbortedIndexation));
            }

            let typed_chunk = match result? {
                TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader } => {
                    let cloneable_chunk = unsafe { as_cloneable_grenad(&word_docids_reader)? };
                    word_docids = Some(cloneable_chunk);
                    let cloneable_chunk =
                        unsafe { as_cloneable_grenad(&exact_word_docids_reader)? };
                    exact_word_docids = Some(cloneable_chunk);
                    TypedChunk::WordDocids { word_docids_reader, exact_word_docids_reader }
                }
                TypedChunk::WordPairProximityDocids(chunk) => {
                    let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
                    word_pair_proximity_docids = Some(cloneable_chunk);
                    TypedChunk::WordPairProximityDocids(chunk)
                }
                TypedChunk::WordPositionDocids(chunk) => {
                    let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
                    word_position_docids = Some(cloneable_chunk);
                    TypedChunk::WordPositionDocids(chunk)
                }
                TypedChunk::WordFidDocids(chunk) => {
                    let cloneable_chunk = unsafe { as_cloneable_grenad(&chunk)? };
                    word_fid_docids = Some(cloneable_chunk);
                    TypedChunk::WordFidDocids(chunk)
                }
                otherwise => otherwise,
            };

            let (docids, is_merged_database) =
                write_typed_chunk_into_index(typed_chunk, self.index, self.wtxn, index_is_empty)?;
            if !docids.is_empty() {
                final_documents_ids |= docids;
                let documents_seen_count = final_documents_ids.len();
                (self.progress)(UpdateIndexingStep::IndexDocuments {
                    documents_seen: documents_seen_count as usize,
                    total_documents: documents_count,
                });
                debug!(
                    "We have seen {} documents on {} total document so far",
                    documents_seen_count, documents_count
                );
            }
            if is_merged_database {
                databases_seen += 1;
                (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
                    databases_seen,
                    total_databases: TOTAL_POSTING_DATABASE_COUNT,
                });
            }
        }

        // We write the field distribution into the main database
        self.index.put_field_distribution(self.wtxn, &field_distribution)?;

        // We write the primary key field id into the main database
        self.index.put_primary_key(self.wtxn, &primary_key)?;

        // We write the external documents ids into the main database.
        let mut external_documents_ids = self.index.external_documents_ids(self.wtxn)?;
        external_documents_ids.insert_ids(&new_external_documents_ids)?;
        let external_documents_ids = external_documents_ids.into_static();
        self.index.put_external_documents_ids(self.wtxn, &external_documents_ids)?;

        let all_documents_ids = index_documents_ids | new_documents_ids;
        self.index.put_documents_ids(self.wtxn, &all_documents_ids)?;

        self.execute_prefix_databases(
            word_docids,
            exact_word_docids,
            word_pair_proximity_docids,
            word_position_docids,
            word_fid_docids,
        )?;

        Ok(all_documents_ids.len())
    }

    #[logging_timer::time("IndexDocuments::{}")]
    pub fn execute_prefix_databases(
        self,
        word_docids: Option<grenad::Reader<CursorClonableMmap>>,
        exact_word_docids: Option<grenad::Reader<CursorClonableMmap>>,
        word_pair_proximity_docids: Option<grenad::Reader<CursorClonableMmap>>,
        word_position_docids: Option<grenad::Reader<CursorClonableMmap>>,
        word_fid_docids: Option<grenad::Reader<CursorClonableMmap>>,
    ) -> Result<()>
    where
        FP: Fn(UpdateIndexingStep) + Sync,
        FA: Fn() -> bool + Sync,
    {
        puffin::profile_function!();

        // Merged databases are already been indexed, we start from this count;
        let mut databases_seen = MERGED_DATABASE_COUNT;

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        databases_seen += 1;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        let previous_words_prefixes_fst =
            self.index.words_prefixes_fst(self.wtxn)?.map_data(|cow| cow.into_owned())?;

        // Run the words prefixes update operation.
        let mut builder = WordsPrefixesFst::new(self.wtxn, self.index);
        if let Some(value) = self.config.words_prefix_threshold {
            builder.threshold(value);
        }
        if let Some(value) = self.config.max_prefix_length {
            builder.max_prefix_length(value);
        }
        builder.execute()?;

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        let current_prefix_fst;
        let common_prefix_fst_words_tmp;
        let common_prefix_fst_words: Vec<_>;
        let new_prefix_fst_words;
        let del_prefix_fst_words;

        {
            puffin::profile_scope!("compute_prefix_diffs");

            current_prefix_fst = self.index.words_prefixes_fst(self.wtxn)?;

            // We retrieve the common words between the previous and new prefix word fst.
            common_prefix_fst_words_tmp = fst_stream_into_vec(
                previous_words_prefixes_fst.op().add(&current_prefix_fst).intersection(),
            );
            common_prefix_fst_words = common_prefix_fst_words_tmp
                .as_slice()
                .linear_group_by_key(|x| x.chars().next().unwrap())
                .collect();

            // We retrieve the newly added words between the previous and new prefix word fst.
            new_prefix_fst_words = fst_stream_into_vec(
                current_prefix_fst.op().add(&previous_words_prefixes_fst).difference(),
            );

            // We compute the set of prefixes that are no more part of the prefix fst.
            del_prefix_fst_words = fst_stream_into_hashset(
                previous_words_prefixes_fst.op().add(&current_prefix_fst).difference(),
            );
        }

        databases_seen += 1;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        if let Some(word_docids) = word_docids {
            execute_word_prefix_docids(
                self.wtxn,
                word_docids,
                self.index.word_docids,
                self.index.word_prefix_docids,
                self.indexer_config,
                &new_prefix_fst_words,
                &common_prefix_fst_words,
                &del_prefix_fst_words,
            )?;
        }

        if let Some(exact_word_docids) = exact_word_docids {
            execute_word_prefix_docids(
                self.wtxn,
                exact_word_docids,
                self.index.exact_word_docids,
                self.index.exact_word_prefix_docids,
                self.indexer_config,
                &new_prefix_fst_words,
                &common_prefix_fst_words,
                &del_prefix_fst_words,
            )?;
        }

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        databases_seen += 1;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        if let Some(word_pair_proximity_docids) = word_pair_proximity_docids {
            // Run the word prefix pair proximity docids update operation.
            PrefixWordPairsProximityDocids::new(
                self.wtxn,
                self.index,
                self.indexer_config.chunk_compression_type,
                self.indexer_config.chunk_compression_level,
            )
            .execute(
                word_pair_proximity_docids,
                &new_prefix_fst_words,
                &common_prefix_fst_words,
                &del_prefix_fst_words,
            )?;
        }

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        databases_seen += 1;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        if let Some(word_position_docids) = word_position_docids {
            // Run the words prefix position docids update operation.
            let mut builder = WordPrefixIntegerDocids::new(
                self.wtxn,
                self.index.word_prefix_position_docids,
                self.index.word_position_docids,
            );
            builder.chunk_compression_type = self.indexer_config.chunk_compression_type;
            builder.chunk_compression_level = self.indexer_config.chunk_compression_level;
            builder.max_nb_chunks = self.indexer_config.max_nb_chunks;
            builder.max_memory = self.indexer_config.max_memory;

            builder.execute(
                word_position_docids,
                &new_prefix_fst_words,
                &common_prefix_fst_words,
                &del_prefix_fst_words,
            )?;
        }
        if let Some(word_fid_docids) = word_fid_docids {
            // Run the words prefix fid docids update operation.
            let mut builder = WordPrefixIntegerDocids::new(
                self.wtxn,
                self.index.word_prefix_fid_docids,
                self.index.word_fid_docids,
            );
            builder.chunk_compression_type = self.indexer_config.chunk_compression_type;
            builder.chunk_compression_level = self.indexer_config.chunk_compression_level;
            builder.max_nb_chunks = self.indexer_config.max_nb_chunks;
            builder.max_memory = self.indexer_config.max_memory;
            builder.execute(
                word_fid_docids,
                &new_prefix_fst_words,
                &common_prefix_fst_words,
                &del_prefix_fst_words,
            )?;
        }

        if (self.should_abort)() {
            return Err(Error::InternalError(InternalError::AbortedIndexation));
        }

        databases_seen += 1;
        (self.progress)(UpdateIndexingStep::MergeDataIntoFinalDatabase {
            databases_seen,
            total_databases: TOTAL_POSTING_DATABASE_COUNT,
        });

        Ok(())
    }
}

/// Run the word prefix docids update operation.
#[allow(clippy::too_many_arguments)]
fn execute_word_prefix_docids(
    txn: &mut heed::RwTxn,
    reader: grenad::Reader<Cursor<ClonableMmap>>,
    word_docids_db: Database<Str, RoaringBitmapCodec>,
    word_prefix_docids_db: Database<Str, RoaringBitmapCodec>,
    indexer_config: &IndexerConfig,
    new_prefix_fst_words: &[String],
    common_prefix_fst_words: &[&[String]],
    del_prefix_fst_words: &HashSet<Vec<u8>>,
) -> Result<()> {
    puffin::profile_function!();

    let cursor = reader.into_cursor()?;
    let mut builder = WordPrefixDocids::new(txn, word_docids_db, word_prefix_docids_db);
    builder.chunk_compression_type = indexer_config.chunk_compression_type;
    builder.chunk_compression_level = indexer_config.chunk_compression_level;
    builder.max_nb_chunks = indexer_config.max_nb_chunks;
    builder.max_memory = indexer_config.max_memory;
    builder.execute(cursor, new_prefix_fst_words, common_prefix_fst_words, del_prefix_fst_words)?;
    Ok(())
}

#[cfg(test)]
mod tests {
    use big_s::S;
    use maplit::hashset;

    use super::*;
    use crate::documents::documents_batch_reader_from_objects;
    use crate::index::tests::TempIndex;
    use crate::search::TermsMatchingStrategy;
    use crate::update::DeleteDocuments;
    use crate::{db_snap, BEU16};

    #[test]
    fn simple_document_replacement() {
        let index = TempIndex::new();

        // First we send 3 documents with ids from 1 to 3.
        index
            .add_documents(documents!([
                { "id": 1, "name": "kevin" },
                { "id": 2, "name": "kevina" },
                { "id": 3, "name": "benoit" }
            ]))
            .unwrap();

        // Check that there is 3 documents now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);
        drop(rtxn);

        // Second we send 1 document with id 1, to erase the previous ones.
        index.add_documents(documents!([ { "id": 1, "name": "updated kevin" } ])).unwrap();

        // Check that there is **always** 3 documents.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);
        drop(rtxn);

        // Third we send 3 documents again to replace the existing ones.
        index
            .add_documents(documents!([
                { "id": 1, "name": "updated second kevin" },
                { "id": 2, "name": "updated kevina" },
                { "id": 3, "name": "updated benoit" }
            ]))
            .unwrap();

        // Check that there is **always** 3 documents.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);
        let count = index.all_documents(&rtxn).unwrap().count();
        assert_eq!(count, 3);

        drop(rtxn);
    }

    #[test]
    fn simple_document_merge() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        // First we send 3 documents with duplicate ids and
        // change the index method to merge documents.
        index
            .add_documents(documents!([
                { "id": 1, "name": "kevin" },
                { "id": 1, "name": "kevina" },
                { "id": 1, "name": "benoit" }
            ]))
            .unwrap();

        // Check that there is only 1 document now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 1);

        // Check that we get only one document from the database.
        let docs = index.documents(&rtxn, Some(0)).unwrap();
        assert_eq!(docs.len(), 1);
        let (id, doc) = docs[0];
        assert_eq!(id, 0);

        // Check that this document is equal to the last one sent.
        let mut doc_iter = doc.iter();
        assert_eq!(doc_iter.next(), Some((0, &b"1"[..])));
        assert_eq!(doc_iter.next(), Some((1, &br#""benoit""#[..])));
        assert_eq!(doc_iter.next(), None);
        drop(rtxn);

        // Second we send 1 document with id 1, to force it to be merged with the previous one.
        index.add_documents(documents!([ { "id": 1, "age": 25 } ])).unwrap();

        // Check that there is **always** 1 document.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 1);

        // Check that we get only one document from the database.
        // Since the document has been deleted and re-inserted, its internal docid has been incremented to 1
        let docs = index.documents(&rtxn, Some(1)).unwrap();
        assert_eq!(docs.len(), 1);
        let (id, doc) = docs[0];
        assert_eq!(id, 1);

        // Check that this document is equal to the last one sent.
        let mut doc_iter = doc.iter();
        assert_eq!(doc_iter.next(), Some((0, &b"1"[..])));
        assert_eq!(doc_iter.next(), Some((1, &br#""benoit""#[..])));
        assert_eq!(doc_iter.next(), Some((2, &b"25"[..])));
        assert_eq!(doc_iter.next(), None);
        drop(rtxn);
    }

    #[test]
    fn not_auto_generated_documents_ids() {
        let index = TempIndex::new();

        let result = index.add_documents(documents!([
            { "name": "kevin" },
            { "name": "kevina" },
            { "name": "benoit" }
        ]));
        assert!(result.is_err());

        // Check that there is no document.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 0);
        drop(rtxn);
    }

    #[test]
    fn simple_auto_generated_documents_ids() {
        let mut index = TempIndex::new();
        index.index_documents_config.autogenerate_docids = true;
        // First we send 3 documents with ids from 1 to 3.
        index
            .add_documents(documents!([
                { "name": "kevin" },
                { "name": "kevina" },
                { "name": "benoit" }
            ]))
            .unwrap();

        // Check that there is 3 documents now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);

        let docs = index.documents(&rtxn, vec![0, 1, 2]).unwrap();
        let (_id, obkv) = docs.iter().find(|(_id, kv)| kv.get(0) == Some(br#""kevin""#)).unwrap();
        let kevin_uuid: String = serde_json::from_slice(obkv.get(1).unwrap()).unwrap();
        drop(rtxn);

        // Second we send 1 document with the generated uuid, to erase the previous ones.
        index.add_documents(documents!([ { "name": "updated kevin", "id": kevin_uuid } ])).unwrap();

        // Check that there is **always** 3 documents.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);

        // the document 0 has been deleted and reinserted with the id 3
        let docs = index.documents(&rtxn, vec![1, 2, 3]).unwrap();
        let kevin_position =
            docs.iter().position(|(_, d)| d.get(0).unwrap() == br#""updated kevin""#).unwrap();
        assert_eq!(kevin_position, 2);
        let (_, doc) = docs[kevin_position];

        // Check that this document is equal to the last
        // one sent and that an UUID has been generated.
        assert_eq!(doc.get(0), Some(&br#""updated kevin""#[..]));
        // This is an UUID, it must be 36 bytes long plus the 2 surrounding string quotes (").
        assert_eq!(doc.get(1).unwrap().len(), 36 + 2);
        drop(rtxn);
    }

    #[test]
    fn reordered_auto_generated_documents_ids() {
        let mut index = TempIndex::new();

        // First we send 3 documents with ids from 1 to 3.
        index
            .add_documents(documents!([
                { "id": 1, "name": "kevin" },
                { "id": 2, "name": "kevina" },
                { "id": 3, "name": "benoit" }
            ]))
            .unwrap();

        // Check that there is 3 documents now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 3);
        drop(rtxn);

        // Second we send 1 document without specifying the id.
        index.index_documents_config.autogenerate_docids = true;
        index.add_documents(documents!([ { "name": "new kevin" } ])).unwrap();

        // Check that there is 4 documents now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 4);
        drop(rtxn);
    }

    #[test]
    fn empty_update() {
        let index = TempIndex::new();

        // First we send 0 documents and only headers.
        index.add_documents(documents!([])).unwrap();

        // Check that there is no documents.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 0);
        drop(rtxn);
    }

    #[test]
    fn invalid_documents_ids() {
        let index = TempIndex::new();

        // First we send 1 document with an invalid id.
        // There is a space in the document id.
        index.add_documents(documents!([ { "id": "brume bleue", "name": "kevin" } ])).unwrap_err();

        // Then we send 1 document with a valid id.
        index.add_documents(documents!([ { "id": 32, "name": "kevin" } ])).unwrap();

        // Check that there is 1 document now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 1);
        drop(rtxn);
    }

    #[test]
    fn complex_documents() {
        let index = TempIndex::new();

        // First we send 3 documents with an id for only one of them.
        index
            .add_documents(documents!([
                { "id": 0, "name": "kevin", "object": { "key1": "value1", "key2": "value2" } },
                { "id": 1, "name": "kevina", "array": ["I", "am", "fine"] },
                { "id": 2, "name": "benoit", "array_of_object": [{ "wow": "amazing" }] }
            ]))
            .unwrap();

        // Check that there is 1 documents now.
        let rtxn = index.read_txn().unwrap();

        // Search for a sub object value
        let result = index.search(&rtxn).query(r#""value2""#).execute().unwrap();
        assert_eq!(result.documents_ids, vec![0]);

        // Search for a sub array value
        let result = index.search(&rtxn).query(r#""fine""#).execute().unwrap();
        assert_eq!(result.documents_ids, vec![1]);

        // Search for a sub array sub object key
        let result = index.search(&rtxn).query(r#""amazing""#).execute().unwrap();
        assert_eq!(result.documents_ids, vec![2]);

        drop(rtxn);
    }

    #[test]
    fn simple_documents_replace() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::ReplaceDocuments;

        index.add_documents(documents!([
          { "id": 2,    "title": "Pride and Prejudice",                    "author": "Jane Austin",              "genre": "romance",    "price": 3.5, "_geo": { "lat": 12, "lng": 42 } },
          { "id": 456,  "title": "Le Petit Prince",                        "author": "Antoine de Saint-Exupéry", "genre": "adventure" , "price": 10.0 },
          { "id": 1,    "title": "Alice In Wonderland",                    "author": "Lewis Carroll",            "genre": "fantasy",    "price": 25.99 },
          { "id": 1344, "title": "The Hobbit",                             "author": "J. R. R. Tolkien",         "genre": "fantasy" },
          { "id": 4,    "title": "Harry Potter and the Half-Blood Prince", "author": "J. K. Rowling",            "genre": "fantasy" },
          { "id": 42,   "title": "The Hitchhiker's Guide to the Galaxy",   "author": "Douglas Adams", "_geo": { "lat": 35, "lng": 23 } }
        ])).unwrap();

        db_snap!(index, word_docids, "initial");

        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        index
            .add_documents(documents!([
                {"id":4,"title":"Harry Potter and the Half-Blood Princess"},
                {"id":456,"title":"The Little Prince"}
            ]))
            .unwrap();

        index
            .add_documents(documents!([
                { "id": 2, "author": "J. Austen", "date": "1813" }
            ]))
            .unwrap();

        // Check that there is **always** 6 documents.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 6);
        let count = index.all_documents(&rtxn).unwrap().count();
        assert_eq!(count, 6);

        db_snap!(index, word_docids, "updated");
        db_snap!(index, soft_deleted_documents_ids, "updated", @"[0, 1, 4, ]");

        drop(rtxn);
    }

    #[test]
    fn mixed_geo_documents() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::ReplaceDocuments;

        // We send 6 documents and mix the ones that have _geo and those that don't have it.
        index
            .add_documents(documents!([
              { "id": 2, "price": 3.5, "_geo": { "lat": 12, "lng": 42 } },
              { "id": 456 },
              { "id": 1 },
              { "id": 1344 },
              { "id": 4 },
              { "id": 42, "_geo": { "lat": 35, "lng": 23 } }
            ]))
            .unwrap();

        index
            .update_settings(|settings| {
                settings.set_filterable_fields(hashset!(S("_geo")));
            })
            .unwrap();
    }

    #[test]
    fn geo_error() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::ReplaceDocuments;

        index
            .update_settings(|settings| {
                settings.set_filterable_fields(hashset!(S("_geo")));
            })
            .unwrap();

        let error = index
            .add_documents(documents!([
              { "id": 0, "_geo": { "lng": 42 } }
            ]))
            .unwrap_err();
        assert_eq!(
            &error.to_string(),
            r#"Could not find latitude in the document with the id: `0`. Was expecting a `_geo.lat` field."#
        );

        let error = index
            .add_documents(documents!([
              { "id": 0, "_geo": { "lat": 42 } }
            ]))
            .unwrap_err();
        assert_eq!(
            &error.to_string(),
            r#"Could not find longitude in the document with the id: `0`. Was expecting a `_geo.lng` field."#
        );

        let error = index
            .add_documents(documents!([
              { "id": 0, "_geo": { "lat": "lol", "lng": 42 } }
            ]))
            .unwrap_err();
        assert_eq!(
            &error.to_string(),
            r#"Could not parse latitude in the document with the id: `0`. Was expecting a finite number but instead got `"lol"`."#
        );

        let error = index
            .add_documents(documents!([
              { "id": 0, "_geo": { "lat": [12, 13], "lng": 42 } }
            ]))
            .unwrap_err();
        assert_eq!(
            &error.to_string(),
            r#"Could not parse latitude in the document with the id: `0`. Was expecting a finite number but instead got `[12,13]`."#
        );

        let error = index
            .add_documents(documents!([
              { "id": 0, "_geo": { "lat": 12, "lng": "hello" } }
            ]))
            .unwrap_err();
        assert_eq!(
            &error.to_string(),
            r#"Could not parse longitude in the document with the id: `0`. Was expecting a finite number but instead got `"hello"`."#
        );
    }

    #[test]
    fn delete_documents_then_insert() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
                { "objectId": 123, "title": "Pride and Prejudice", "comment": "A great book" },
                { "objectId": 456, "title": "Le Petit Prince",     "comment": "A french book" },
                { "objectId": 1,   "title": "Alice In Wonderland", "comment": "A weird book" },
                { "objectId": 30,  "title": "Hamlet", "_geo": { "lat": 12, "lng": 89 } }
            ]))
            .unwrap();
        let mut wtxn = index.write_txn().unwrap();
        assert_eq!(index.primary_key(&wtxn).unwrap(), Some("objectId"));

        // Delete not all of the documents but some of them.
        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
        builder.delete_external_id("30");
        builder.execute().unwrap();

        let external_documents_ids = index.external_documents_ids(&wtxn).unwrap();
        assert!(external_documents_ids.get("30").is_none());
        wtxn.commit().unwrap();

        index
            .add_documents(documents!([
                { "objectId": 30,  "title": "Hamlet", "_geo": { "lat": 12, "lng": 89 } }
            ]))
            .unwrap();

        let wtxn = index.write_txn().unwrap();
        let external_documents_ids = index.external_documents_ids(&wtxn).unwrap();
        assert!(external_documents_ids.get("30").is_some());
        wtxn.commit().unwrap();

        index
            .add_documents(documents!([
                { "objectId": 30,  "title": "Hamlet", "_geo": { "lat": 12, "lng": 89 } }
            ]))
            .unwrap();
    }

    #[test]
    fn index_more_than_256_fields() {
        let index = TempIndex::new();

        let mut big_object = serde_json::Map::new();
        big_object.insert(S("id"), serde_json::Value::from("wow"));
        for i in 0..1000 {
            let key = i.to_string();
            big_object.insert(key, serde_json::Value::from("I am a text!"));
        }

        let documents = documents_batch_reader_from_objects([big_object]);
        index.add_documents(documents).unwrap();
    }

    #[test]
    fn index_more_than_1000_positions_in_a_field() {
        let index = TempIndex::new_with_map_size(4096 * 100_000); // 400 MB
        let mut content = String::with_capacity(382101);
        for i in 0..=u16::MAX {
            content.push_str(&format!("{i} "));
        }
        index
            .add_documents(documents!({
                "id": "wow",
                "content": content
            }))
            .unwrap();

        let rtxn = index.read_txn().unwrap();

        assert!(index.word_docids.get(&rtxn, "0").unwrap().is_some());
        assert!(index.word_docids.get(&rtxn, "64").unwrap().is_some());
        assert!(index.word_docids.get(&rtxn, "256").unwrap().is_some());
        assert!(index.word_docids.get(&rtxn, "1024").unwrap().is_some());
        assert!(index.word_docids.get(&rtxn, "32768").unwrap().is_some());
        assert!(index.word_docids.get(&rtxn, "65535").unwrap().is_some());
    }

    #[test]
    fn index_documents_with_zeroes() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
                {
                    "id": 2,
                    "title": "Prideand Prejudice",
                    "au{hor": "Jane Austin",
                    "genre": "romance",
                    "price$": "3.5$",
                },
                {
                    "id": 456,
                    "title": "Le Petit Prince",
                    "au{hor": "Antoine de Saint-Exupéry",
                    "genre": "adventure",
                    "price$": "10.0$",
                },
                {
                    "id": 1,
                    "title": "Wonderland",
                    "au{hor": "Lewis Carroll",
                    "genre": "fantasy",
                    "price$": "25.99$",
                },
                {
                    "id": 4,
                    "title": "Harry Potter ing fantasy\0lood Prince",
                    "au{hor": "J. K. Rowling",
                    "genre": "fantasy\0",
                },
            ]))
            .unwrap();
    }

    #[test]
    fn index_documents_with_nested_fields() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
                {
                    "id": 0,
                    "title": "The zeroth document",
                },
                {
                    "id": 1,
                    "title": "The first document",
                    "nested": {
                        "object": "field",
                        "machin": "bidule",
                    },
                },
                {
                    "id": 2,
                    "title": "The second document",
                    "nested": [
                        "array",
                        {
                            "object": "field",
                        },
                        {
                            "prout": "truc",
                            "machin": "lol",
                        },
                    ],
                },
                {
                    "id": 3,
                    "title": "The third document",
                    "nested": "I lied",
                },
            ]))
            .unwrap();

        index
            .update_settings(|settings| {
                let searchable_fields = vec![S("title"), S("nested.object"), S("nested.machin")];
                settings.set_searchable_fields(searchable_fields);

                let faceted_fields = hashset!(S("title"), S("nested.object"), S("nested.machin"));
                settings.set_filterable_fields(faceted_fields);
            })
            .unwrap();

        let rtxn = index.read_txn().unwrap();

        let facets = index.faceted_fields(&rtxn).unwrap();
        assert_eq!(facets, hashset!(S("title"), S("nested.object"), S("nested.machin")));

        // testing the simple query search
        let mut search = crate::Search::new(&rtxn, &index);
        search.query("document");
        search.terms_matching_strategy(TermsMatchingStrategy::default());
        // all documents should be returned
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids.len(), 4);

        search.query("zeroth");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![0]);
        search.query("first");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1]);
        search.query("second");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![2]);
        search.query("third");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![3]);

        search.query("field");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1, 2]);

        search.query("lol");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![2]);

        search.query("object");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert!(documents_ids.is_empty());

        search.query("array");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert!(documents_ids.is_empty()); // nested is not searchable

        search.query("lied");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert!(documents_ids.is_empty()); // nested is not searchable

        // testing the filters
        let mut search = crate::Search::new(&rtxn, &index);
        search.filter(crate::Filter::from_str(r#"title = "The first document""#).unwrap().unwrap());
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1]);

        search.filter(crate::Filter::from_str(r#"nested.object = field"#).unwrap().unwrap());
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1, 2]);

        search.filter(crate::Filter::from_str(r#"nested.machin = bidule"#).unwrap().unwrap());
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1]);

        search.filter(crate::Filter::from_str(r#"nested = array"#).unwrap().unwrap());
        let error = search.execute().map(|_| unreachable!()).unwrap_err(); // nested is not filterable
        assert!(matches!(error, crate::Error::UserError(crate::UserError::InvalidFilter(_))));

        search.filter(crate::Filter::from_str(r#"nested = "I lied""#).unwrap().unwrap());
        let error = search.execute().map(|_| unreachable!()).unwrap_err(); // nested is not filterable
        assert!(matches!(error, crate::Error::UserError(crate::UserError::InvalidFilter(_))));
    }

    #[test]
    fn index_documents_with_nested_primary_key() {
        let index = TempIndex::new();

        index
            .update_settings(|settings| {
                settings.set_primary_key("complex.nested.id".to_owned());
            })
            .unwrap();

        index
            .add_documents(documents!([
                {
                    "complex": {
                        "nested": {
                            "id": 0,
                        },
                    },
                    "title": "The zeroth document",
                },
                {
                    "complex.nested": {
                        "id": 1,
                    },
                    "title": "The first document",
                },
                {
                    "complex": {
                        "nested.id": 2,
                    },
                    "title": "The second document",
                },
                {
                    "complex.nested.id": 3,
                    "title": "The third document",
                },
            ]))
            .unwrap();

        let rtxn = index.read_txn().unwrap();

        // testing the simple query search
        let mut search = crate::Search::new(&rtxn, &index);
        search.query("document");
        search.terms_matching_strategy(TermsMatchingStrategy::default());
        // all documents should be returned
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids.len(), 4);

        search.query("zeroth");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![0]);
        search.query("first");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1]);
        search.query("second");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![2]);
        search.query("third");
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![3]);
    }

    #[test]
    fn retrieve_a_b_nested_document_id() {
        let index = TempIndex::new();

        index
            .update_settings(|settings| {
                settings.set_primary_key("a.b".to_owned());
            })
            .unwrap();

        // There must be an issue with the primary key no present in the given document
        index.add_documents(documents!({ "a" : { "b" : { "c" :  1 }}})).unwrap_err();
    }

    #[test]
    fn retrieve_a_b_c_nested_document_id() {
        let index = TempIndex::new();

        index
            .update_settings(|settings| {
                settings.set_primary_key("a.b.c".to_owned());
            })
            .unwrap();
        index.add_documents(documents!({ "a" : { "b" : { "c" :  1 }}})).unwrap();

        let rtxn = index.read_txn().unwrap();
        let external_documents_ids = index.external_documents_ids(&rtxn).unwrap();
        assert!(external_documents_ids.get("1").is_some());
    }

    #[test]
    fn test_facets_generation() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
                {
                    "id": 0,
                    "dog": {
                        "race": {
                            "bernese mountain": "zeroth",
                        },
                    },
                },
                {
                    "id": 1,
                    "dog.race": {
                        "bernese mountain": "first",
                    },
                },
                {
                    "id": 2,
                    "dog.race.bernese mountain": "second",
                },
                {
                    "id": 3,
                    "dog": {
                        "race.bernese mountain": "third"
                    },
                },
            ]))
            .unwrap();

        index
            .update_settings(|settings| {
                settings.set_filterable_fields(hashset!(String::from("dog")));
            })
            .unwrap();

        db_snap!(index, facet_id_string_docids, @r###"
        3   0  first        1  [1, ]
        3   0  second       1  [2, ]
        3   0  third        1  [3, ]
        3   0  zeroth       1  [0, ]
        "###);
        db_snap!(index, field_id_docid_facet_strings, @r###"
        3   0    zeroth       zeroth
        3   1    first        first
        3   2    second       second
        3   3    third        third
        "###);
        db_snap!(index, string_faceted_documents_ids, @r###"
        0   []
        1   []
        2   []
        3   [0, 1, 2, 3, ]
        "###);

        let rtxn = index.read_txn().unwrap();

        let hidden = index.faceted_fields(&rtxn).unwrap();

        assert_eq!(hidden, hashset!(S("dog"), S("dog.race"), S("dog.race.bernese mountain")));

        for (s, i) in [("zeroth", 0), ("first", 1), ("second", 2), ("third", 3)] {
            let mut search = crate::Search::new(&rtxn, &index);
            let filter = format!(r#""dog.race.bernese mountain" = {s}"#);
            search.filter(crate::Filter::from_str(&filter).unwrap().unwrap());
            let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
            assert_eq!(documents_ids, vec![i]);
        }
        // Reset the settings
        index
            .update_settings(|settings| {
                settings.reset_filterable_fields();
            })
            .unwrap();

        db_snap!(index, facet_id_string_docids, @"");
        db_snap!(index, field_id_docid_facet_strings, @"");
        db_snap!(index, string_faceted_documents_ids, @r###"
        0   []
        1   []
        2   []
        3   [0, 1, 2, 3, ]
        "###);

        let rtxn = index.read_txn().unwrap();

        let facets = index.faceted_fields(&rtxn).unwrap();

        assert_eq!(facets, hashset!());

        // update the settings to test the sortable
        index
            .update_settings(|settings| {
                settings.set_sortable_fields(hashset!(S("dog.race")));
            })
            .unwrap();

        db_snap!(index, facet_id_string_docids, @r###"
        3   0  first        1  [1, ]
        3   0  second       1  [2, ]
        3   0  third        1  [3, ]
        3   0  zeroth       1  [0, ]
        "###);
        db_snap!(index, field_id_docid_facet_strings, @r###"
        3   0    zeroth       zeroth
        3   1    first        first
        3   2    second       second
        3   3    third        third
        "###);
        db_snap!(index, string_faceted_documents_ids, @r###"
        0   []
        1   []
        2   []
        3   [0, 1, 2, 3, ]
        "###);

        let rtxn = index.read_txn().unwrap();

        let facets = index.faceted_fields(&rtxn).unwrap();

        assert_eq!(facets, hashset!(S("dog.race"), S("dog.race.bernese mountain")));

        let mut search = crate::Search::new(&rtxn, &index);
        search.sort_criteria(vec![crate::AscDesc::Asc(crate::Member::Field(S(
            "dog.race.bernese mountain",
        )))]);
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids, vec![1, 2, 3, 0]);
    }

    #[test]
    fn index_2_times_documents_split_by_zero_document_indexation() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
                {"id": 0, "name": "Kerollmops", "score": 78},
                {"id": 1, "name": "ManyTheFish", "score": 75},
                {"id": 2, "name": "Ferdi", "score": 39},
                {"id": 3, "name": "Tommy", "score": 33}
            ]))
            .unwrap();

        // Check that there is 4 document now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 4);

        index.add_documents(documents!([])).unwrap();

        // Check that there is 4 document now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 4);

        index
            .add_documents(documents!([
                {"id": 0, "name": "Kerollmops", "score": 78},
                {"id": 1, "name": "ManyTheFish", "score": 75},
                {"id": 2, "name": "Ferdi", "score": 39},
                {"id": 3, "name": "Tommy", "score": 33}
            ]))
            .unwrap();

        // Check that there is 4 document now.
        let rtxn = index.read_txn().unwrap();
        let count = index.number_of_documents(&rtxn).unwrap();
        assert_eq!(count, 4);
    }

    #[cfg(feature = "chinese")]
    #[test]
    fn test_meilisearch_1714() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
              {"id": "123", "title": "小化妆包" },
              {"id": "456", "title": "Ipad 包" }
            ]))
            .unwrap();

        let rtxn = index.read_txn().unwrap();

        // Only the first document should match.
        let count = index.word_docids.get(&rtxn, "huàzhuāngbāo").unwrap().unwrap().len();
        assert_eq!(count, 1);

        // Only the second document should match.
        let count = index.word_docids.get(&rtxn, "bāo").unwrap().unwrap().len();
        assert_eq!(count, 1);

        let mut search = crate::Search::new(&rtxn, &index);
        search.query("化妆包");
        search.terms_matching_strategy(TermsMatchingStrategy::default());

        // only 1 document should be returned
        let crate::SearchResult { documents_ids, .. } = search.execute().unwrap();
        assert_eq!(documents_ids.len(), 1);
    }

    /// We try to index documents with words that are too long here,
    /// it should not return any error.
    #[test]
    fn text_with_too_long_words() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
              {"id": 1, "title": "a".repeat(256) },
              {"id": 2, "title": "b".repeat(512) },
              {"id": 3, "title": format!("{} {}", "c".repeat(250), "d".repeat(250)) },
            ]))
            .unwrap();
    }

    #[test]
    fn text_with_too_long_keys() {
        let index = TempIndex::new();
        let script = "https://bug.example.com/meilisearch/milli.saml2?ROLE=Programmer-1337&SAMLRequest=Cy1ytcZT1Po%2L2IY2y9Unru8rgnW4qWfPiI0EpT7P8xjJV8PeQikRL%2E8D9A4pj9tmbymbQCQwGmGjPMK7qwXFPX4DH52JO2b7n6TXjuR7zkIFuYdzdY2rwRNBPgCL7ihclEm9zyIjKZQ%2JTqiwfXxWjnI0KEYQYHdwd6Q%2Fx%28BDLNsvmL54CCY2F4RWeRs4eqWfn%2EHqxlhreFzax4AiQ2tgOtV5thOaaWqrhZD%2Py70nuyZWNTKwciGI43AoHg6PThANsQ5rAY5amzN%2ufbs1swETUXlLZuOut5YGpYPZfY6STJWNp4QYSUOUXBZpdElYsH7UHZ7VhJycgyt%28aTK0GW6GbKne2tJM0hgSczOqndg6RFa9WsnSBi4zMcaEfYur4WlSsHDYInF9ROousKqVMZ6H8%2gbUissaLh1eXRGo8KEJbyEHbhVVKGD%28kx4cfKjx9fT3pkeDTdvDrVn25jIzi9wHyt9l1lWc8ICnCvXCVUPP%2BjBG4wILR29gMV9Ux2QOieQm2%2Fycybhr8sBGCl30mHC7blvWt%2T3mrCHQoS3VK49PZNPqBZO9C7vOjOWoszNkJx4QckWV%2FZFvbpzUUkiBiehr9F%2FvQSxz9lzv68GwbTu9fr638p%2FQM%3D&RelayState=https%3A%2F%example.bug.com%2Fde&SigAlg=http%3A%2F%2Fwww.w3.org%2F2000%2F09%2Fxmldsig%23rsa-sha1&Signature=AZFpkhFFII7PodiewTovaGnLQKUVZp0qOCCcBIUkJ6P5by3lE3Lldj9pKaFu4wz4j%2B015HEhDvF0LlAmwwES85vdGh%2FpD%2cIQPRUEjdCbQkQDd3dy1mMXbpXxSe4QYcv9Ni7tqNTQxekpO1gE7rtg6zC66EU55uM9aj9abGQ034Vly%2F6IJ08bvAq%2B%2FB9KruLstuiNWnlXTfNGsOxGLK7%2BXr94LTkat8m%2FMan6Qr95%2KeR5TmmqaQIE4N9H6o4TopT7mXr5CF2Z3";

        // Create 200 documents with a long text
        let content = {
            let documents_iter = (0..200i32)
                .map(|i| serde_json::json!({ "id": i, "script": script }))
                .filter_map(|json| match json {
                    serde_json::Value::Object(object) => Some(object),
                    _ => None,
                });
            documents_batch_reader_from_objects(documents_iter)
        };
        // Index those 200 long documents
        index.add_documents(content).unwrap();

        // Index one long document
        index
            .add_documents(documents!([
              {"id": 400, "script": script },
            ]))
            .unwrap();
    }

    #[test]
    fn index_documents_in_multiple_transforms() {
        let index = TempIndex::new();

        let doc1 = documents! {[{
            "id": 228142,
            "title": "asdsad",
            "state": "automated",
            "priority": "normal",
            "public_uid": "37ccf021",
            "project_id": 78207,
            "branch_id_number": 0
        }]};

        let doc2 = documents! {[{
            "id": 228143,
            "title": "something",
            "state": "automated",
            "priority": "normal",
            "public_uid": "39c6499b",
            "project_id": 78207,
            "branch_id_number": 0
        }]};

        {
            let mut wtxn = index.write_txn().unwrap();
            index.put_primary_key(&mut wtxn, "id").unwrap();
            wtxn.commit().unwrap();
        }

        index.add_documents(doc1).unwrap();
        index.add_documents(doc2).unwrap();

        let wtxn = index.read_txn().unwrap();

        let map = index.external_documents_ids(&wtxn).unwrap().to_hash_map();
        let ids = map.values().collect::<HashSet<_>>();

        assert_eq!(ids.len(), map.len());
    }

    #[test]
    fn index_documents_check_exists_database() {
        let content = || {
            documents!([
                {
                    "id": 0,
                    "colour": 0,
                },
                {
                    "id": 1,
                    "colour": []
                },
                {
                    "id": 2,
                    "colour": {}
                },
                {
                    "id": 3,
                    "colour": null
                },
                {
                    "id": 4,
                    "colour": [1]
                },
                {
                    "id": 5
                },
                {
                    "id": 6,
                    "colour": {
                        "green": 1
                    }
                },
                {
                    "id": 7,
                    "colour": {
                        "green": {
                            "blue": []
                        }
                    }
                }
            ])
        };

        let check_ok = |index: &Index| {
            let rtxn = index.read_txn().unwrap();
            let facets = index.faceted_fields(&rtxn).unwrap();
            assert_eq!(facets, hashset!(S("colour"), S("colour.green"), S("colour.green.blue")));

            let colour_id = index.fields_ids_map(&rtxn).unwrap().id("colour").unwrap();
            let colour_green_id = index.fields_ids_map(&rtxn).unwrap().id("colour.green").unwrap();

            let bitmap_colour =
                index.facet_id_exists_docids.get(&rtxn, &BEU16::new(colour_id)).unwrap().unwrap();
            assert_eq!(bitmap_colour.into_iter().collect::<Vec<_>>(), vec![0, 1, 2, 3, 4, 6, 7]);

            let bitmap_colour_green = index
                .facet_id_exists_docids
                .get(&rtxn, &BEU16::new(colour_green_id))
                .unwrap()
                .unwrap();
            assert_eq!(bitmap_colour_green.into_iter().collect::<Vec<_>>(), vec![6, 7]);
        };

        let faceted_fields = hashset!(S("colour"));

        let index = TempIndex::new();
        index.add_documents(content()).unwrap();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        check_ok(&index);

        let index = TempIndex::new();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        index.add_documents(content()).unwrap();
        check_ok(&index);
    }

    #[test]
    fn index_documents_check_is_null_database() {
        let content = || {
            documents!([
                {
                    "id": 0,
                    "colour": null,
                },
                {
                    "id": 1,
                    "colour": [null], // must not be returned
                },
                {
                    "id": 6,
                    "colour": {
                        "green": null
                    }
                },
                {
                    "id": 7,
                    "colour": {
                        "green": {
                            "blue": null
                        }
                    }
                },
                {
                    "id": 8,
                    "colour": 0,
                },
                {
                    "id": 9,
                    "colour": []
                },
                {
                    "id": 10,
                    "colour": {}
                },
                {
                    "id": 12,
                    "colour": [1]
                },
                {
                    "id": 13
                },
                {
                    "id": 14,
                    "colour": {
                        "green": 1
                    }
                },
                {
                    "id": 15,
                    "colour": {
                        "green": {
                            "blue": []
                        }
                    }
                }
            ])
        };

        let check_ok = |index: &Index| {
            let rtxn = index.read_txn().unwrap();
            let facets = index.faceted_fields(&rtxn).unwrap();
            assert_eq!(facets, hashset!(S("colour"), S("colour.green"), S("colour.green.blue")));

            let colour_id = index.fields_ids_map(&rtxn).unwrap().id("colour").unwrap();
            let colour_green_id = index.fields_ids_map(&rtxn).unwrap().id("colour.green").unwrap();
            let colour_blue_id =
                index.fields_ids_map(&rtxn).unwrap().id("colour.green.blue").unwrap();

            let bitmap_null_colour =
                index.facet_id_is_null_docids.get(&rtxn, &BEU16::new(colour_id)).unwrap().unwrap();
            assert_eq!(bitmap_null_colour.into_iter().collect::<Vec<_>>(), vec![0]);

            let bitmap_colour_green = index
                .facet_id_is_null_docids
                .get(&rtxn, &BEU16::new(colour_green_id))
                .unwrap()
                .unwrap();
            assert_eq!(bitmap_colour_green.into_iter().collect::<Vec<_>>(), vec![2]);

            let bitmap_colour_blue = index
                .facet_id_is_null_docids
                .get(&rtxn, &BEU16::new(colour_blue_id))
                .unwrap()
                .unwrap();
            assert_eq!(bitmap_colour_blue.into_iter().collect::<Vec<_>>(), vec![3]);
        };

        let faceted_fields = hashset!(S("colour"));

        let index = TempIndex::new();
        index.add_documents(content()).unwrap();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        check_ok(&index);

        let index = TempIndex::new();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        index.add_documents(content()).unwrap();
        check_ok(&index);
    }

    #[test]
    fn index_documents_check_is_empty_database() {
        let content = || {
            documents!([
                {"id": 0, "tags": null },
                {"id": 1, "tags": [null] },
                {"id": 2, "tags": [] },
                {"id": 3, "tags": ["hello","world"] },
                {"id": 4, "tags": [""] },
                {"id": 5 },
                {"id": 6, "tags": {} },
                {"id": 7, "tags": {"green": "cool"} },
                {"id": 8, "tags": {"green": ""} },
                {"id": 9, "tags": "" },
                {"id": 10, "tags": { "green": null } },
                {"id": 11, "tags": { "green": { "blue": null } } },
                {"id": 12, "tags": { "green": { "blue": [] } } }
            ])
        };

        let check_ok = |index: &Index| {
            let rtxn = index.read_txn().unwrap();
            let facets = index.faceted_fields(&rtxn).unwrap();
            assert_eq!(facets, hashset!(S("tags"), S("tags.green"), S("tags.green.blue")));

            let tags_id = index.fields_ids_map(&rtxn).unwrap().id("tags").unwrap();
            let tags_green_id = index.fields_ids_map(&rtxn).unwrap().id("tags.green").unwrap();
            let tags_blue_id = index.fields_ids_map(&rtxn).unwrap().id("tags.green.blue").unwrap();

            let bitmap_empty_tags =
                index.facet_id_is_empty_docids.get(&rtxn, &BEU16::new(tags_id)).unwrap().unwrap();
            assert_eq!(bitmap_empty_tags.into_iter().collect::<Vec<_>>(), vec![2, 6, 9]);

            let bitmap_tags_green = index
                .facet_id_is_empty_docids
                .get(&rtxn, &BEU16::new(tags_green_id))
                .unwrap()
                .unwrap();
            assert_eq!(bitmap_tags_green.into_iter().collect::<Vec<_>>(), vec![8]);

            let bitmap_tags_blue = index
                .facet_id_is_empty_docids
                .get(&rtxn, &BEU16::new(tags_blue_id))
                .unwrap()
                .unwrap();
            assert_eq!(bitmap_tags_blue.into_iter().collect::<Vec<_>>(), vec![12]);
        };

        let faceted_fields = hashset!(S("tags"));

        let index = TempIndex::new();
        index.add_documents(content()).unwrap();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        check_ok(&index);

        let index = TempIndex::new();
        index
            .update_settings(|settings| {
                settings.set_filterable_fields(faceted_fields.clone());
            })
            .unwrap();
        index.add_documents(content()).unwrap();
        check_ok(&index);
    }

    #[test]
    fn primary_key_must_not_contain_floats() {
        let index = TempIndex::new_with_map_size(4096 * 100);

        let doc1 = documents! {[{
            "id": -228142,
            "title": "asdsad",
        }]};

        let doc2 = documents! {[{
            "id": 228143.56,
            "title": "something",
        }]};

        let doc3 = documents! {[{
            "id": -228143.56,
            "title": "something",
        }]};

        let doc4 = documents! {[{
            "id": 2.0,
            "title": "something",
        }]};

        index.add_documents(doc1).unwrap();
        index.add_documents(doc2).unwrap_err();
        index.add_documents(doc3).unwrap_err();
        index.add_documents(doc4).unwrap_err();
    }

    #[test]
    fn primary_key_must_not_contain_whitespace() {
        let index = TempIndex::new();

        let doc1 = documents! {[{
            "id": " 1",
            "title": "asdsad",
        }]};

        let doc2 = documents! {[{
            "id": "\t2",
            "title": "something",
        }]};

        let doc3 = documents! {[{
            "id": "\r3",
            "title": "something",
        }]};

        let doc4 = documents! {[{
            "id": "\n4",
            "title": "something",
        }]};

        index.add_documents(doc1).unwrap_err();
        index.add_documents(doc2).unwrap_err();
        index.add_documents(doc3).unwrap_err();
        index.add_documents(doc4).unwrap_err();
    }

    #[test]
    fn primary_key_inference() {
        let index = TempIndex::new();

        let doc_no_id = documents! {[{
            "title": "asdsad",
            "state": "automated",
            "priority": "normal",
            "branch_id_number": 0
        }]};
        assert!(matches!(
            index.add_documents(doc_no_id),
            Err(Error::UserError(UserError::NoPrimaryKeyCandidateFound))
        ));

        let doc_multiple_ids = documents! {[{
            "id": 228143,
            "title": "something",
            "state": "automated",
            "priority": "normal",
            "public_uid": "39c6499b",
            "project_id": 78207,
            "branch_id_number": 0
        }]};

        let Err(Error::UserError(UserError::MultiplePrimaryKeyCandidatesFound { candidates })) =
            index.add_documents(doc_multiple_ids)
        else {
            panic!("Expected Error::UserError(MultiplePrimaryKeyCandidatesFound)")
        };

        assert_eq!(candidates, vec![S("id"), S("project_id"), S("public_uid"),]);

        let doc_inferable = documents! {[{
            "video": "test.mp4",
            "id": 228143,
            "title": "something",
            "state": "automated",
            "priority": "normal",
            "public_uid_": "39c6499b",
            "project_id_": 78207,
            "branch_id_number": 0
        }]};

        index.add_documents(doc_inferable).unwrap();

        let txn = index.read_txn().unwrap();

        assert_eq!(index.primary_key(&txn).unwrap().unwrap(), "id");
    }

    #[test]
    fn long_words_must_be_skipped() {
        let index = TempIndex::new();

        // this is obviousy too long
        let long_word = "lol".repeat(1000);
        let doc1 = documents! {[{
            "id": "1",
            "title": long_word,
        }]};

        index.add_documents(doc1).unwrap();

        let rtxn = index.read_txn().unwrap();
        let words_fst = index.words_fst(&rtxn).unwrap();
        assert!(!words_fst.contains(&long_word));
    }

    #[test]
    fn long_facet_values_must_not_crash() {
        let index = TempIndex::new();

        // this is obviousy too long
        let long_word = "lol".repeat(1000);
        let doc1 = documents! {[{
            "id": "1",
            "title": long_word,
        }]};

        index
            .update_settings(|settings| {
                settings.set_filterable_fields(hashset! { S("title") });
            })
            .unwrap();

        index.add_documents(doc1).unwrap();
    }

    #[cfg(feature = "default")]
    #[test]
    fn store_detected_script_and_language_per_document_during_indexing() {
        use charabia::{Language, Script};
        let index = TempIndex::new();
        index
            .add_documents(documents!([
                { "id": 1, "title": "The quick (\"brown\") fox can't jump 32.3 feet, right? Brr, it's 29.3°F!" },
                { "id": 2, "title": "人人生而自由﹐在尊嚴和權利上一律平等。他們賦有理性和良心﹐並應以兄弟關係的精神互相對待。" },
                { "id": 3, "title": "הַשּׁוּעָל הַמָּהִיר (״הַחוּם״) לֹא יָכוֹל לִקְפֹּץ 9.94 מֶטְרִים, נָכוֹן? ברר, 1.5°C- בַּחוּץ!" },
                { "id": 4, "title": "関西国際空港限定トートバッグ すもももももももものうち" },
                { "id": 5, "title": "ภาษาไทยง่ายนิดเดียว" },
                { "id": 6, "title": "The quick 在尊嚴和權利上一律平等。" },
            ]))
            .unwrap();

        let rtxn = index.read_txn().unwrap();
        let key_jpn = (Script::Cj, Language::Jpn);
        let key_cmn = (Script::Cj, Language::Cmn);
        let cj_jpn_docs = index.script_language_documents_ids(&rtxn, &key_jpn).unwrap().unwrap();
        let cj_cmn_docs = index.script_language_documents_ids(&rtxn, &key_cmn).unwrap().unwrap();
        let expected_cj_jpn_docids = [3].iter().collect();
        assert_eq!(cj_jpn_docs, expected_cj_jpn_docids);
        let expected_cj_cmn_docids = [1, 5].iter().collect();
        assert_eq!(cj_cmn_docs, expected_cj_cmn_docids);
    }

    #[test]
    fn add_and_delete_documents_in_single_transform() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 1, "doggo": "kevin" },
            { "id": 2, "doggo": { "name": "bob", "age": 20 } },
            { "id": 3, "name": "jean", "age": 25 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"3");

        let (builder, removed) = builder.remove_documents(vec![S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"1");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 3,
            number_of_documents: 2,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"doggo":"kevin"}
        {"id":3,"name":"jean","age":25}
        "###);
    }

    #[test]
    fn add_update_and_delete_documents_in_single_transform() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 1, "doggo": "kevin" },
            { "id": 2, "doggo": { "name": "bob", "age": 20 } },
            { "id": 3, "name": "jean", "age": 25 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"3");

        let documents = documents!([
            { "id": 2, "catto": "jorts" },
            { "id": 3, "legs": 4 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"2");

        let (builder, removed) = builder.remove_documents(vec![S("1"), S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"2");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 5,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":3,"name":"jean","age":25,"legs":4}
        "###);
    }

    #[test]
    fn add_document_and_in_another_transform_update_and_delete_documents() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 1, "doggo": "kevin" },
            { "id": 2, "doggo": { "name": "bob", "age": 20 } },
            { "id": 3, "name": "jean", "age": 25 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"3");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 3,
            number_of_documents: 3,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"doggo":"kevin"}
        {"id":2,"doggo":{"name":"bob","age":20}}
        {"id":3,"name":"jean","age":25}
        "###);

        // A first batch of documents has been inserted

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 2, "catto": "jorts" },
            { "id": 3, "legs": 4 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"2");

        let (builder, removed) = builder.remove_documents(vec![S("1"), S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"2");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 2,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":3,"name":"jean","age":25,"legs":4}
        "###);
    }

    #[test]
    fn delete_document_and_then_add_documents_in_the_same_transform() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let (builder, removed) = builder.remove_documents(vec![S("1"), S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"0");

        let documents = documents!([
            { "id": 2, "doggo": { "name": "jean", "age": 20 } },
            { "id": 3, "name": "bob", "age": 25 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"2");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 2,
            number_of_documents: 2,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":2,"doggo":{"name":"jean","age":20}}
        {"id":3,"name":"bob","age":25}
        "###);
    }

    #[test]
    fn delete_the_same_document_multiple_time() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let (builder, removed) =
            builder.remove_documents(vec![S("1"), S("2"), S("1"), S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"0");

        let documents = documents!([
            { "id": 1, "doggo": "kevin" },
            { "id": 2, "doggo": { "name": "jean", "age": 20 } },
            { "id": 3, "name": "bob", "age": 25 },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"3");

        let (builder, removed) =
            builder.remove_documents(vec![S("1"), S("2"), S("1"), S("2")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"2");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 3,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":3,"name":"bob","age":25}
        "###);
    }

    #[test]
    fn add_document_and_in_another_transform_delete_the_document_then_add_it_again() {
        let mut index = TempIndex::new();
        index.index_documents_config.update_method = IndexDocumentsMethod::UpdateDocuments;

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 1, "doggo": "kevin" },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"1");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 1,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"doggo":"kevin"}
        "###);

        // A first batch of documents has been inserted

        let mut wtxn = index.write_txn().unwrap();
        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let (builder, removed) = builder.remove_documents(vec![S("1")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"1");

        let documents = documents!([
            { "id": 1, "catto": "jorts" },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"1");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 1,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"catto":"jorts"}
        "###);
    }

    #[test]
    fn test_word_fid_position() {
        let index = TempIndex::new();

        index
            .add_documents(documents!([
              {"id": 0, "text": "sun flowers are looking at the sun" },
              {"id": 1, "text": "sun flowers are looking at the sun" },
              {"id": 2, "text": "the sun is shining today" },
              {
                "id": 3,
                "text": "a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a a a a a a
                a a a a a a a a a a a a a a a a a a a a a "
             }
            ]))
            .unwrap();

        db_snap!(index, word_fid_docids, 1, @"bf3355e493330de036c8823ddd1dbbd9");
        db_snap!(index, word_position_docids, 1, @"896d54b29ed79c4c6f14084f326dcf6f");

        index
            .add_documents(documents!([
              {"id": 4, "text": "sun flowers are looking at the sun" },
              {"id": 5, "text2": "sun flowers are looking at the sun" },
              {"id": 6, "text": "b b b" },
              {
                "id": 7,
                "text2": "a a a a"
             }
            ]))
            .unwrap();

        db_snap!(index, word_fid_docids, 2, @"a48d3f88db33f94bc23110a673ea49e4");
        db_snap!(index, word_position_docids, 2, @"3c9e66c6768ae2cf42b46b2c46e46a83");

        let mut wtxn = index.write_txn().unwrap();

        // Delete not all of the documents but some of them.
        let mut builder = DeleteDocuments::new(&mut wtxn, &index).unwrap();
        builder.strategy(DeletionStrategy::AlwaysHard);
        builder.delete_external_id("0");
        builder.delete_external_id("3");
        let result = builder.execute().unwrap();
        println!("{result:?}");

        wtxn.commit().unwrap();

        db_snap!(index, word_fid_docids, 3, @"4c2e2a1832e5802796edc1638136d933");
        db_snap!(index, word_position_docids, 3, @"74f556b91d161d997a89468b4da1cb8f");
    }

    #[test]
    fn reproduce_the_bug() {
        /*
            [milli/examples/fuzz.rs:69] &batches = [
            Batch(
                [
                    AddDoc(
                        { "id": 1, "doggo": "bernese" }, => internal 0
                    ),
                ],
            ),
            Batch(
                [
                    DeleteDoc(
                        1, => delete internal 0
                    ),
                    AddDoc(
                        { "id": 0, "catto": "jorts" }, => internal 1
                    ),
                ],
            ),
            Batch(
                [
                    AddDoc(
                        { "id": 1, "catto": "jorts" }, => internal 2
                    ),
                ],
            ),
        ]
        */
        let mut index = TempIndex::new();
        index.index_documents_config.deletion_strategy = DeletionStrategy::AlwaysHard;

        // START OF BATCH

        println!("--- ENTERING BATCH 1");

        let mut wtxn = index.write_txn().unwrap();

        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        // OP

        let documents = documents!([
            { "id": 1, "doggo": "bernese" },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"1");

        // FINISHING
        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 1,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"doggo":"bernese"}
        "###);
        db_snap!(index, external_documents_ids, @r###"
        soft:
        hard:
        1                        0
        "###);

        // A first batch of documents has been inserted

        // BATCH 2

        println!("--- ENTERING BATCH 2");

        let mut wtxn = index.write_txn().unwrap();

        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let (builder, removed) = builder.remove_documents(vec![S("1")]).unwrap();
        insta::assert_display_snapshot!(removed.unwrap(), @"1");

        let documents = documents!([
            { "id": 0, "catto": "jorts" },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"1");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 1,
            number_of_documents: 1,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":0,"catto":"jorts"}
        "###);

        db_snap!(index, external_documents_ids, @r###"
        soft:
        hard:
        0                        1
        "###);

        db_snap!(index, soft_deleted_documents_ids, @"[]");

        // BATCH 3

        println!("--- ENTERING BATCH 3");

        let mut wtxn = index.write_txn().unwrap();

        let builder = IndexDocuments::new(
            &mut wtxn,
            &index,
            &index.indexer_config,
            index.index_documents_config.clone(),
            |_| (),
            || false,
        )
        .unwrap();

        let documents = documents!([
            { "id": 1, "catto": "jorts" },
        ]);
        let (builder, added) = builder.add_documents(documents).unwrap();
        insta::assert_display_snapshot!(added.unwrap(), @"1");

        let addition = builder.execute().unwrap();
        insta::assert_debug_snapshot!(addition, @r###"
        DocumentAdditionResult {
            indexed_documents: 1,
            number_of_documents: 2,
        }
        "###);
        wtxn.commit().unwrap();

        db_snap!(index, documents, @r###"
        {"id":1,"catto":"jorts"}
        {"id":0,"catto":"jorts"}
        "###);

        // Ensuring all the returned IDs actually exists
        let rtxn = index.read_txn().unwrap();
        let res = index.search(&rtxn).execute().unwrap();
        index.documents(&rtxn, res.documents_ids).unwrap();
    }
}