h2database / h2database/h2database
Merge and update on a table with a composite primary key extremely slow.
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- Dominant language
- Java
- Stars
- 4.6k
- Forks
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- Avg merge
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- Merged PRs (30d)
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Description
Merge and update on a table with a composite primary key extremely slow.
After upgrading to the latest version, 2.3.232 merge and update statements became up to 25 times slower on a table with a composite primary key.
Had to replace the composite key with an ID (IDENTITY) column as primary key to reduce the execution time for merge and only use one WHERE condition on ID for update.
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Research direction
The report concerns the 2.3.232 regression in MERGE and UPDATE statements on tables with composite primary keys, but names no source files or tests. Start by reproducing the reported slowdown and compare execution time with an IDENTITY primary key; done means restoring comparable performance for composite-key MERGE and UPDATE operations.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java, sql
- Domain
- databases, performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100