[MDEV-7620] Transaction lock wait is missing number of lock waits Created: 2015-02-23 Updated: 2020-11-09 Resolved: 2015-02-23 |
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| Status: | Closed |
| Project: | MariaDB Server |
| Component/s: | Storage Engine - InnoDB, Storage Engine - XtraDB |
| Affects Version/s: | 10.0.16 |
| Fix Version/s: | 10.0.17, 10.1.5 |
| Type: | Bug | Priority: | Trivial |
| Reporter: | Jan Lindström (Inactive) | Assignee: | Jan Lindström (Inactive) |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Description |
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Customer request. Currently, innodb transaction lock information does not contain any information how long/how many times transaction has waited a row/table lock. |
| Comments |
| Comment by Jan Lindström (Inactive) [ 2015-02-23 ] |
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revno: 4616 |
| Comment by Marko Mäkelä [ 2020-11-09 ] |
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It turns out that this change was effectively reverted in MariaDB 10.2.2 when the InnoDB changes from MySQL 5.7.9 and 5.7.14 were applied. We still reserve two machine words related to this in each trx_t, but those data members are not being read or written anywhere. A proper implementation of this should expose the data via PERFORMANCE_SCHEMA and include some tests. |
| Comment by Marko Mäkelä [ 2020-11-09 ] |
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I removed the unused data structures in order to reduce the memory footprint in future 10.2 and later releases. If this feature is considered useful, it should be designed and implemented properly. InnoDB transaction data is being exported via confusingly named views in INFORMATION_SCHEMA. Logically, properties of individual transactions should be made available via PERFORMANCE_SCHEMA. It looks like MariaDB 10.0 and 10.1 exported the information only via SHOW ENGINE INNODB STATUS. |