[MDEV-33069] Instant Modify Column Created: 2023-12-19  Updated: 2023-12-19

Status: Open
Project: MariaDB Server
Component/s: None
Fix Version/s: None

Type: New Feature Priority: Major
Reporter: zhangyuan Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Blocks
is blocked by MDEV-33066 Tencent requested features Open
Relates
relates to MDEV-11424 Instant ALTER TABLE of failure-free r... Closed
relates to MDEV-15563 Instant failure-free data type conver... Closed

 Description   

Supports to change datatype of columns to compatible datatype instantly, like: char(100) to varchar(200), int to bigint. Instant modify column only records column modification information in the data dictionary table, avoiding data copying, which can significantly speedup the performance of some time-consuming DDL operations.

 Comments   
Comment by Marko Mäkelä [ 2023-12-19 ]

We tried something similar in MDEV-15563. In MDEV-11424 there is a table of ALTER TABLE operations that were considered during the development of MariaDB Server 10.4.

I think that the MDEV-11369 and MDEV-15562 compatible way of implementing this for InnoDB would be to extend the metadata record, and simply store the newest table definition in the data dictionary. If affected the columns are indexed, I think that it is simplest to rebuild the indexes.

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