[MDEV-14307] LOCK_DURATION always NULL in METADATA_LOCK_INFO Created: 2017-11-07 Updated: 2018-05-17 Resolved: 2018-05-17 |
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| Status: | Closed |
| Project: | MariaDB Server |
| Component/s: | Locking, Plugins |
| Affects Version/s: | 10.0.26, 10.1.15, 10.2.8 |
| Fix Version/s: | N/A |
| Type: | Bug | Priority: | Major |
| Reporter: | Hartmut Holzgraefe | Assignee: | Sergey Vojtovich |
| Resolution: | Duplicate | Votes: | 1 |
| Labels: | None | ||
| Issue Links: |
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| Description |
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The LOCK_DURATION column of the I_S.METADATA_LOCK_INFO table provided by the metadata lock info plugin is populated just fine in 10.0, but only shows NULL in 10.1 and 10.2. How to reproduce: try examples form https://mariadb.com/kb/en/library/information-schema-metadata_lock_info-table/ |
| Comments |
| Comment by Hartmut Holzgraefe [ 2017-11-07 ] |
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Turns out this change was intentional as fix for Unfortunately it was never documented as such, and it is not clear whether it's supposed to stay that way forever or to be fixed again in some future version ... |
| Comment by Valerii Kravchuk [ 2017-11-07 ] |
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Just wanted to add that there is some way to get this information, hopefully without crashes and "properly" in the performance_schema.metadata_locks table in upstream MySQL 5.7+. Maybe we should try to get it in a similar way for plugin, at least for 10.2+, or prove that upstream implementation has bugs and report them? |
| Comment by Sergey Vojtovich [ 2017-11-22 ] |
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Upstream uses different code to implement this, so they can't be affected by this particular issue. There's substantial difference in approaches used by I_S and PFS tables: the former iterates live array, the latter notifies PFS whenever change occurs. A perfect solution would be to merge performance_schema.metadata_locks implementation and get rid of I_S plugin. This particular issue was supposed to be fixed in scope of MDEV-10275. I wonder how important it is to have this field store proper information? |
| Comment by Sergey Vojtovich [ 2018-05-17 ] |
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Duplicate of MDEV-10275. |