MyRocks Limitations¶

The MyRocks storage engine lacks the following features compared to InnoDB:

• Online DDL
• ALTER TABLE ... EXCHANGE PARTITION
• SAVEPOINT
• Transportable tablespace
• Foreign keys
• Spatial indexes
• Fulltext indexes
• Gap locks

You should also consider the following:

• *_bin (e.g. latin1_bin) or binary collation should be used on CHAR and VARCHAR indexed columns. By default, MyRocks prevents creating indexes with non-binary collations (including latin1). You can optionally use it by setting rocksdb_strict_collation_exceptions to t1 (table names with regex format), but non-binary covering indexes other than latin1 (excluding german1) still require a primary key lookup to return the CHAR or VARCHAR column.
• Either ORDER BY DESC or ORDER BY ASC is slow. This is because of “Prefix Key Encoding” feature in RocksDB. See http://www.slideshare.net/matsunobu/myrocks-deep-dive/58 for details. By default, ascending scan is faster and descending scan is slower. If the “reverse column family” is configured, then descending scan will be faster and ascending scan will be slower. Note that InnoDB also imposes a cost when the index is scanned in the opposite order.
• MyRocks does not support operating as either a master or a slave in any replication topology that is not exclusively row-based. Statement-based and mixed-format binary logging is not supported. For more information, see Replication Formats.