# maximum\_table\_memory

SingleStore will not allow writes to any table once the cumulative memory in use by all tables in SingleStore reaches `maximum_table_memory` (SingleStore will become read-only). `SELECT` and `DELETE` queries will still be allowed even once the limit is reached. `UPDATE`, `INSERT` , `CREATE TABLE`, `ALTER TABLE`, `CREATE INDEX` or `DROP INDEX` statements will fail with an error message once the limit has been reached. Query compilations are also disallowed once the limit is reached.

This setting is designed to allow SELECT queries to allocate temporary memory for sorting, hash group-by, and so on. The `maximum_table_memory` must be set to a value lower than `maximum_memory`. By default, `maximum_table_memory` is set to 90% of `maximum_memory`, which translates to about 80% of physical memory on the host machine.

If the `maximum_table_memory` limit has been reached, `DELETE` queries can still be executed to remove data from the table; however large `DELETE` queries may fail if the memory used by SingleStore reaches `maximum_memory`.

Caution should be taken as `DELETE` queries allocate extra memory to mark rows as deleted. For rowstore tables, this equates to roughly 40 + 8\**number\_of\_indexes* bytes per deleted row. For columnstore tables, the memory usage will be lower because of how rows are marked to be deleted (roughly *num\_rows\_in\_table*/8 bytes if you delete a row in every segment file in the table).

If the table is narrow, such as containing a small number of int columns, `DELETE` queries will show up as a relatively large spike in memory usage compared to the size of the table.

The memory for a deleted row is reclaimed after the transaction commits and the memory is freed asynchronously by the garbage collector. For more information, see the [DELETE](https://docs.singlestore.com/db/v9.1/reference/sql-reference/data-manipulation-language-dml/delete.md) reference topic.

Replicating databases will pause if memory use reaches `maximum_table_memory` while replicating data. If memory becomes available again - say some data is deleted - replication will automatically continue.

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Modified at: September 19, 2022

Source: [/db/v9.1/user-and-cluster-administration/maintain-your-cluster/managing-memory/maximum-table-memory/](https://docs.singlestore.com/db/v9.1/user-and-cluster-administration/maintain-your-cluster/managing-memory/maximum-table-memory/)

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