> ## Documentation Index
> Fetch the complete documentation index at: https://docs.firebolt.io/llms.txt
> Use this file to discover all available pages before exploring further.

> Query the information_schema.engine_caches view to inspect cache usage across engine nodes.

# Engine caches

You can use the `information_schema.engine_caches` view to return information about the caches of each node in the engine.

```sql theme={"theme":{"light":"css-variables","dark":"css-variables"}}
SELECT
  *
FROM
  information_schema.engine_caches
```

## Columns in information\_schema.engine\_caches

Each row has the following columns with information about each node in the engine.

| Column Name               | Data Type | Description                                                           |
| :------------------------ | :-------- | :-------------------------------------------------------------------- |
| cluster\_ordinal          | BIGINT    | The ordinal number of the cluster.                                    |
| node\_ordinal             | BIGINT    | The ordinal number of the node.                                       |
| type                      | TEXT      | The type of the cache, see below for possible values.                 |
| num\_entries              | BIGINT    | The number of entries in the cache.                                   |
| size\_bytes               | BIGINT    | The size of the cache in bytes.                                       |
| entry\_size\_limit\_bytes | BIGINT    | The size limit of an entry in the cache in bytes.                     |
| storage                   | TEXT      | The storage type of the cache, currently either `ram` or `ssd`.       |
| pool                      | TEXT      | The pool of the cache. Entries in the same pool are evicted together. |
| pool\_size\_limit\_bytes  | BIGINT    | The size limit of the pool in bytes.                                  |

## Currently reported cache types

| Type                           | Description                                                                                                                                                                                                                                       |
| :----------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `automated_column_statistics`  | In-memory cache for [automated column statistics](/performance-and-observability/query-planning/automated-column-statistics).                                                                                                                     |
| `external_scan_files`          | Stores the content of external scan files on the SSD.                                                                                                                                                                                             |
| `external_scan_buffered_files` | In-memory cache for external scan files.                                                                                                                                                                                                          |
| `external_scan_files_metadata` | In-memory metadata for the files reported through `external_scan_files`.                                                                                                                                                                          |
| `history_based_statistics`     | In-memory cache for [history-based statistics](/performance-and-observability/query-planning/history-based-statistics).                                                                                                                           |
| `iceberg_catalog`              | In-memory cache for the [Iceberg](/guides/iceberg-and-data-lake/iceberg) catalog.                                                                                                                                                                 |
| `join_hash_table`              | In-memory cache for the hash table used by the `Join` operator. Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult).                                                                         |
| `join_pruning`                 | In-memory cache for join pruning. Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult).                                                                                                       |
| `list_iceberg`                 | In-memory cache for file lists of [Iceberg](/guides/iceberg-and-data-lake/iceberg) tables. Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult).                                              |
| `materialized_reusable`        | In-memory cache for CTEs marked as [`materialized reusable`](/reference-sql/commands/queries/select#reusable-common-table-expressions). Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult). |
| `parquet_statistics`           | In-memory cache for column-level statistics of parquet files that are used for pruning.                                                                                                                                                           |
| `result`                       | In-memory result cache. Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult).                                                                                                                 |
| `scan`                         | In-memory cache for table scans. Part of the [query cache](/performance-and-observability/runtime/understand-query-performance-subresult).                                                                                                        |
| `unclassified`                 | Additional in-memory [query cache](/performance-and-observability/runtime/understand-query-performance-subresult) entries.                                                                                                                        |
| `vector_index`                 | In-memory cache for vector indexes.                                                                                                                                                                                                               |
| `tablet`                       | Caches the tablet files of Firebolt's managed file format on the SSD.                                                                                                                                                                             |
| `tablet_metadata`              | In-memory metadata for the files reported through `tablet`.                                                                                                                                                                                       |
| `tablet_marks`                 | In-memory cache for tablet marks enabling faster table scan pruning.                                                                                                                                                                              |
| `tablet_recovery`              | Partially written tablets.                                                                                                                                                                                                                        |