# Supported storage engines for MariaDB on Amazon RDS
<a name="MariaDB.Concepts.Storage"></a>

RDS for MariaDB supports the following storage engines.

**Topics**
+ [The InnoDB storage engine](#MariaDB.Concepts.Storage.InnoDB)
+ [The MyRocks storage engine](#MariaDB.Concepts.Storage.MyRocks)

Other storage engines aren't currently supported by RDS for MariaDB.

## The InnoDB storage engine
<a name="MariaDB.Concepts.Storage.InnoDB"></a>

Although MariaDB supports multiple storage engines with varying capabilities, not all of them are optimized for recovery and data durability. InnoDB is the recommended storage engine for MariaDB DB instances on Amazon RDS. Amazon RDS features such as point-in-time restore and snapshot restore require a recoverable storage engine and are supported only for the recommended storage engine for the MariaDB version.

For more information, see [InnoDB](https://mariadb.com/kb/en/innodb/).

## The MyRocks storage engine
<a name="MariaDB.Concepts.Storage.MyRocks"></a>

The MyRocks storage engine is available in RDS for MariaDB version 10.6 and higher. Before using the MyRocks storage engine in a production database, we recommend that you perform thorough benchmarking and testing to verify any potential benefits over InnoDB for your use case.

The default parameter group for MariaDB version 10.6 includes MyRocks parameters. For more information, see [Parameters for MariaDB](Appendix.MariaDB.Parameters.md) and [Parameter groups for Amazon RDS](USER_WorkingWithParamGroups.md).

To create a table that uses the MyRocks storage engine, specify `ENGINE=RocksDB` in the `CREATE TABLE` statement. The following example creates a table that uses the MyRocks storage engine.

```
CREATE TABLE test (a INT NOT NULL, b CHAR(10)) ENGINE=RocksDB;
```

We strongly recommend that you don't run transactions that span both InnoDB and MyRocks tables. MariaDB doesn't guarantee ACID (atomicity, consistency, isolation, durability) for transactions across storage engines. Although it is possible to have both InnoDB and MyRocks tables in a DB instance, we don't recommend this approach except during a migration from one storage engine to the other. When both InnoDB and MyRocks tables exist in a DB instance, each storage engine has its own buffer pool, which might cause performance to degrade.

MyRocks doesn’t support `SERIALIZABLE` isolation or gap locks. So, generally you can't use MyRocks with statement-based replication. For more information, see [ MyRocks and Replication](https://mariadb.com/kb/en/myrocks-and-replication/).

Currently, you can modify only the following MyRocks parameters:
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_block_cache_size](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_block_cache_size)
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_bulk_load](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_bulk_load)
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_bulk_load_size](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_bulk_load_size)
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_deadlock_detect](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_deadlock_detect)
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_deadlock_detect_depth](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_deadlock_detect_depth)
+ [https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_max_latest_deadlocks](https://mariadb.com/kb/en/myrocks-system-variables/#rocksdb_max_latest_deadlocks)

The MyRocks storage engine and the InnoDB storage engine can compete for memory based on the settings for the `rocksdb_block_cache_size` and `innodb_buffer_pool_size` parameters. In some cases, you might only intend to use the MyRocks storage engine on a particular DB instance. If so, we recommend setting the `innodb_buffer_pool_size minimal` parameter to a minimal value and setting the `rocksdb_block_cache_size` as high as possible.

You can access MyRocks log files by using the [https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DescribeDBLogFiles.html](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DescribeDBLogFiles.html) and [https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DownloadDBLogFilePortion.html](https://docs.aws.amazon.com/AmazonRDS/latest/APIReference/API_DownloadDBLogFilePortion.html) operations.

For more information about MyRocks, see [MyRocks](https://mariadb.com/kb/en/myrocks/) on the MariaDB website.