Skip to content

Commit 58be605

Browse files
PS-10085 MyRocks limitations section still showing the Online DDL limitation part
modified: docs/limitations.md
1 parent 49f72ce commit 58be605

File tree

1 file changed

+18
-3
lines changed

1 file changed

+18
-3
lines changed

docs/limitations.md

Lines changed: 18 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -2,12 +2,27 @@
22

33
The MyRocks storage engine lacks the following features compared to InnoDB:
44

5-
* [Online DDL](https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl.html) is not supported due to the lack of atomic DDL support.
5+
* [Online DDL](https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl.html) is generally **not supported** due to the lack of atomic DDL support.
66

7-
* There is no `ALTER TABLE ... ALGORITHM=INSTANT` functionality
7+
As of Percona Server for MySQL 8.0.42-33, RocksDB supports a limited set of Instant DDL operations through specific configuration variables:
88

9-
* A partition management operation only supports the `COPY` algorithms, which rebuilds the partition table and moves the data based on the new `PARTITION ... VALUE` definition. In the case of `DROP PARTITION`, the data not moved to another partition is deleted.
9+
* [`--rocksdb_enable_instant_ddl_for_append_column`](variables.md#rocksdb_enable_instant_ddl_for_append_column)
10+
* [`--rocksdb_enable_instant_ddl_for_column_default_changes`](variables.md#rocksdb_enable_instant_ddl_for_column_default_changes)
11+
* [`--rocksdb_enable_instant_ddl_for_drop_index_changes`](variables.md#rocksdb_enable_instant_ddl_for_drop_index_changes)
12+
* [`--rocksdb_enable_instant_ddl_for_table_comment_changes`](variables.md#rocksdb_enable_instant_ddl_for_table_comment_changes)
1013

14+
However, RocksDB has important limitations compared to InnoDB's Instant DDL support.
15+
16+
* The explicit `ALTER TABLE ... ALGORITHM=INSTANT` syntax is not supported for RocksDB tables.
17+
18+
* As of Percona Server for MySQL 8.0.25-15, certain partition management operations support the `INPLACE` algorithm. For example, dropping a partition can now be performed without a full table rebuild.
19+
20+
```sql
21+
ALTER TABLE t1 ALGORITHM=INPLACE, DROP PARTITION p2;
22+
```
23+
However, not all partition operations support `INPLACE`. Operations that modify the partitioning scheme, such as changing `PARTITION ... VALUES`, still require the `COPY` algorithm. In these cases, the table is rebuilt, and data is redistributed according to the new partition definition.
24+
25+
Note that if you use `DROP PARTITION` without reassigning data to another partition, any data contained in the dropped partition will be permanently deleted.
1126

1227
* [ALTER TABLE .. EXCHANGE PARTITION](https://dev.mysql.com/doc/refman/8.0/en/partitioning-management-exchange.html).
1328

0 commit comments

Comments
 (0)