Details
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Bug
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.5, 10.6, 10.11, 11.1(EOL), 11.2, 11.4, 10.2(EOL), 10.3(EOL), 10.4(EOL), 10.7(EOL), 10.8(EOL), 10.9(EOL), 10.10(EOL), 11.0(EOL), 11.3(EOL)
Description
The implementation of innodb_undo_log_truncate=ON in trx_purge_truncate_history() is interfering with log checkpoint and page write performance.
Before MDEV-13564, we used the MySQL 5.7 implementation, which would force a full flush of the entire buffer pool and a sharp log checkpoint. In MDEV-13564 we changed it so that only the pages of the being-truncated undo tablespace would be removed from the buffer pool, but no log checkpoint would be needed.
There is a less intrusive, lazy approach: We can actually let the 'garbage' undo log pages remain in the buffer pool, just like we do on DROP TABLE or DROP INDEX or when freeing pages in any operation: Simply, if the newest modification to a page (FIL_PAGE_LSN) is older than the LSN of the latest tablespace rebuild, we will discard the page, just like in MDEV-15528 we do for pages whose underlying file page has been freed. With this approach, there is no need for trx_purge_truncate_history() to traverse the buffer pool.
For the similar case of shrinking the InnoDB system tablespace (MDEV-14795), there would not be a complete tablespace rebuild (like there is with innodb_undo_log_truncate=ON), so we must only discard pages that are beyond the end of the current tablespace size; their FIL_PAGE_LSN must be older than the latest LSN of shrinking the FSP_SIZE. I think that we can do that by relaxing the logic around invoking fil_invalid_page_access_msg() in fil_space_t::io().
Attachments
Issue Links
- is blocked by
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MDEV-25491 Race condition between DROP TABLE and purge of SYS_INDEXES record
- Closed
- relates to
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MDEV-33213 History list is not shrunk unless there is a pause in the workload
- Closed
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MDEV-13564 TRUNCATE TABLE and undo tablespace truncation are not compatible with Mariabackup
- Closed
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MDEV-14795 InnoDB system tablespace cannot be shrunk
- Closed
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MDEV-15528 Avoid writing freed InnoDB pages
- Closed
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MDEV-33009 Server hangs for a long time with innodb_undo_log_truncate=ON
- Closed