# buffer\_manager\_cached\_memory

> **⚠️ Warning**: `buffer_manager_cached_memory` is read-only and cannot be modified by users.

SingleStore keeps unused Buffer Manager memory mapped instead of returning every freed buffer to the operating system so that later allocations can use it. `Buffer_manager_cached_memory` tracks this cached memory.

While `Total_server_memory` is at or below 90% of `maximum_memory` or at least 10 GB of free memory remains, `Buffer_manager_cached_memory` is capped at 25% of `maximum_memory` on each node. When the cache size reaches the capped limit, additional freed memory blocks (or buffers) are returned to the operating system. Buffers that are already cached are still mapped and left in place, therefore crossing the capped limit does not trim the cache. The cache shrinks when a subsequent allocation uses the cached buffer, and it can get unmapped if another allocation may otherwise exceed `maximum_memory`.

When `Total_server_memory` is above 90% of `maximum_memory` and less than 10 GB of free memory remains, newly freed buffers are cached only until the cache size reaches approximately 1% of `maximum_memory` (vs. the default 25%). Existing cached buffers are not trimmed when this limit applies.

As cached memory stays mapped, `Total_server_memory` includes `Buffer_manager_cached_memory`. After a large rowstore `DELETE`, `Alloc_table_memory` can fall while `Total_server_memory` stays high because the freed memory blocks are still held as unrecycled or cached memory.

The cache is not released on a fixed schedule. Run `TRIGGER GC FLUSH` to explicitly release unused Buffer Manager cached memory.

View the size of cached memory reserved for each node in the output of the `SHOW STATUS EXTENDED` command. For example:

```sql
SHOW STATUS EXTENDED LIKE 'buffer_manager_cached%';

```

```output

+------------------------------+---------+
| Variable_name                |  Value  |
+------------------------------+---------+
| Buffer_manager_cached_memory | 80.0 MB |
+------------------------------+---------+

```

Refer to [Identifying and Reducing Memory Usage](https://docs.singlestore.com/db/v9.0/reference/troubleshooting-reference/identifying-and-reducing-memory-usage/#section-id235465259061611.md) for more information on `Buffer_manager_cached_memory` and `Total_server_memory`.

***

Modified at: October 19, 2026

Source: [/db/v9.0/user-and-cluster-administration/maintain-your-cluster/managing-memory/buffer-manager-cached-memory/](https://docs.singlestore.com/db/v9.0/user-and-cluster-administration/maintain-your-cluster/managing-memory/buffer-manager-cached-memory/)

(An index of the documentation is available at /llms.txt)