[MDEV-17383] BLOB leak when emptying an instantly altered table Created: 2018-10-07  Updated: 2023-04-27

Status: Open
Project: MariaDB Server
Component/s: Storage Engine - InnoDB
Affects Version/s: 10.3.2, 10.4.0
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Marko Mäkelä Assignee: Marko Mäkelä
Resolution: Unresolved Votes: 0
Labels: BLOB, instant

Issue Links:
Blocks
is blocked by MDEV-17197 "1713: Undo log record is too big" fo... Confirmed
Problem/Incident
is caused by MDEV-11369 Instant add column for InnoDB Closed

 Description   

When a table becomes empty after an instant ADD COLUMN operation, it would be converted to the canonical format.

If the added columns had long DEFAULT values, these values can be stored off-page. These pages would not be freed when the table becomes empty.

It appears that btr_free_but_not_root() or similar should be executed in order to mark the BLOB pages freed. Otherwise, the space for the BLOB pages would not be released until the table is dropped or rebuilt.



 Comments   
Comment by Marko Mäkelä [ 2018-10-12 ]

My attempt to reproduce this was blocked by MDEV-17197.

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