# Cache warming for MariaDB on Amazon RDS
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InnoDB cache warming can provide performance gains for your MariaDB DB instance by saving the current state of the buffer pool when the DB instance is shut down, and then reloading the buffer pool from the saved information when the DB instance starts up. This approach bypasses the need for the buffer pool to "warm up" from normal database use and instead preloads the buffer pool with the pages for known common queries. For more information on cache warming, see [ Dumping and restoring the buffer pool](http://mariadb.com/kb/en/mariadb/xtradbinnodb-buffer-pool/#dumping-and-restoring-the-buffer-pool) in the MariaDB documentation.

Cache warming is enabled by default on MariaDB 10.3 and higher DB instances. To enable it, set the `innodb_buffer_pool_dump_at_shutdown` and `innodb_buffer_pool_load_at_startup` parameters to 1 in the parameter group for your DB instance. Changing these parameter values in a parameter group affects all MariaDB DB instances that use that parameter group. To enable cache warming for specific MariaDB DB instances, you might need to create a new parameter group for those DB instances. For information on parameter groups, see [Parameter groups for Amazon RDS](USER_WorkingWithParamGroups.md).

Cache warming primarily provides a performance benefit for DB instances that use standard storage. If you use PIOPS storage, you don't commonly see a significant performance benefit.

**Important**  
If your MariaDB DB instance doesn't shut down normally, such as during a failover, then the buffer pool state isn't saved to disk. In this case, MariaDB loads whatever buffer pool file is available when the DB instance is restarted. No harm is done, but the restored buffer pool might not reflect the most recent state of the buffer pool before the restart. To ensure that you have a recent state of the buffer pool available to warm the cache on startup, we recommend that you periodically dump the buffer pool "on demand." You can dump or load the buffer pool on demand.  
You can create an event to dump the buffer pool automatically and at a regular interval. For example, the following statement creates an event named `periodic_buffer_pool_dump` that dumps the buffer pool every hour.   

```
1. CREATE EVENT periodic_buffer_pool_dump 
2.    ON SCHEDULE EVERY 1 HOUR 
3.    DO CALL mysql.rds_innodb_buffer_pool_dump_now();
```
For more information, see [Events](http://mariadb.com/kb/en/mariadb/stored-programs-and-views-events/) in the MariaDB documentation.

## Dumping and loading the buffer pool on demand
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You can save and load the cache on demand using the following stored procedures:
+ To dump the current state of the buffer pool to disk, call the [mysql.rds\_innodb\_buffer\_pool\_dump\_now](mysql-stored-proc-warming.md#mysql_rds_innodb_buffer_pool_dump_now) stored procedure.
+ To load the saved state of the buffer pool from disk, call the [mysql.rds\_innodb\_buffer\_pool\_load\_now](mysql-stored-proc-warming.md#mysql_rds_innodb_buffer_pool_load_now) stored procedure.
+ To cancel a load operation in progress, call the [mysql.rds\_innodb\_buffer\_pool\_load\_abort](mysql-stored-proc-warming.md#mysql_rds_innodb_buffer_pool_load_abort) stored procedure.