> ## Documentation Index
> Fetch the complete documentation index at: https://meilisearch-6b28dec2-mintlify-code-samples.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Optimize indexing performance with batch statistics

> Learn how to analyze the `progressTrace` to identify and resolve indexing bottlenecks in Meilisearch.

# Optimize indexing performance by analyzing batch statistics

Indexing performance can vary significantly depending on your dataset, index settings, and hardware. The [batch object](/reference/api/batches) provides information about the progress of asynchronous indexing operations.

The `progressTrace` field within the batch object offers a detailed breakdown of where time is spent during the indexing process. Use this data to identify bottlenecks and improve indexing speed.

## Understanding the `progressTrace`

`progressTrace` is a hierarchical trace showing each phase of indexing and how long it took.
Each entry follows the structure:

```json theme={null}
"processing tasks > indexing > extracting word proximity": "33.71s"
```

This means:

* The step occurred during **indexing**.
* The subtask was **extracting word proximity**.
* It took **33.71 seconds**.

Focus on the **longest-running steps** and investigate which index settings or data characteristics influence them.

## Key phases and how to optimize them

### `computing document changes`and `extracting documents`

| Description                                               | Optimization                                                                                             |
| --------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- |
| Meilisearch compares incoming documents to existing ones. | No direct optimization possible. Process duration scales with the number and size of incoming documents. |

### `extracting facets` and `merging facet caches`

| Description                                | Optimization                                                                                                |
| ------------------------------------------ | ----------------------------------------------------------------------------------------------------------- |
| Extracts and merges filterable attributes. | Keep the number of [**filterable attributes**](/reference/api/settings#filterable-attributes) to a minimum. |

### `extracting words` and `merging word caches`

| Description                                   | Optimization                                                                                                                                                   |
| --------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Tokenizes text and builds the inverted index. | Ensure the [searchable attributes](/reference/api/settings#searchable-attributes) list only includes the fields you want to be checked for query word matches. |

### `extracting word proximity` and `merging word proximity`

| Description                                              | Optimization                                                                                                                         |
| -------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------ |
| Builds data structures for phrase and attribute ranking. | Lower the precision of this operation by setting [proximity precision](/reference/api/settings#proximity-precision) to `byAttribute` |

### `waiting for database writes`

| Description                      | Optimization                                                                                                                                       |
| -------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------- |
| Time spent writing data to disk. | No direct optimization possible. Either the disk is too slow or you are writing too much data in a single operation. Avoid HDDs (Hard Disk Drives) |

### `waiting for extractors`

| Description                                  | Optimization                                                                                                                                 |
| -------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------- |
| Time spent waiting for CPU-bound extraction. | No direct optimization possible. Indicates a CPU bottleneck. Use more cores or scale horizontally with [sharding](/learn/advanced/sharding). |

### `post processing facets > strings bulk` / `numbers bulk`

| Description                               | Optimization                                                                                                                                                                                                                  |
| ----------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Processes equality or comparison filters. | - Disable unused [**filter features**](/reference/api/settings#features), such as comparison operators on string values. <br /> - Reduce the number of [**sortable attributes**](reference/api/settings#sortable-attributes). |

### `post processing facets > facet search`

| Description                                                                | Optimization                                                                                               |
| -------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------- |
| Builds structures for the [facet search API](/reference/api/facet_search). | If you don’t use the facet search API, [disable it](/reference/api/settings#update-facet-search-settings). |

### Embeddings

| Trace key                        | Description                          | Optimization                                                                                                                                                                                                                            |
| -------------------------------- | ------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `writing embeddings to database` | Time spent saving vector embeddings. | Use embedding vectors with fewer dimensions. <br />- [Disabling embedding regeneration on document update](/reference/api/documents#vectors). <br />- Consider enabling [binary quantization](/reference/api/settings#binaryquantized). |

### `post processing words > word prefix *`

| Description | Optimization                                                                                                                         |                                                                                                                                                    |
| ----------- | ------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------- |
|             | Builds prefix data for autocomplete. Allows matching documents that begin with a specific query term, instead of only exact matches. | Disable [**prefix search**](/reference/api/settings#prefix-search) (`prefixSearch: disabled`). *This can severely impact search result relevancy.* |

### `post processing words > word fst`

| Description                                    | Optimization                                                                                                                                                           |
| ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Builds the word FST (finite state transducer). | No direct action possible, as FST size reflect the number of different words in the database. Using documents with fewer searchable words may improve operation speed. |

## Example analysis

If you see:

```json theme={null}
"processing tasks > indexing > post processing facets > facet search": "1763.06s"
```

[Facet searching](/learn/filtering_and_sorting/search_with_facet_filters#searching-facet-values) is raking significant indexing time. If your application doesn’t use facets, disable the feature:

```bash theme={null}
curl \
  -X PUT 'MEILISEARCH_URL/indexes/INDEX_UID/settings/facet-search' \
  -H 'Content-Type: application/json' \
  --data-binary 'false'
```

## Learn more

* [Indexing best practices](/learn/indexing/indexing_best_practices)
* [Impact of RAM and multi-threading on indexing performance
  ](/learn/indexing/ram_multithreading_performance)
* [Configuring index settings](/learn/configuration/configuring_index_settings)