Rewrite mysql PaginateBranchesFromHistoryTree query #3509
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yiminc
approved these changes
Oct 18, 2022
yiminc
reviewed
Oct 18, 2022
| ORDER BY shard_id, tree_id, branch_id | ||
| LIMIT ?` | ||
| FROM history_tree | ||
| WHERE shard_id = ? AND ((tree_id = ? AND branch_id > ?) OR tree_id > ?) OR shard_id > ? |
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maybe add some simple comment here that we tried the tuple comparison but it result in mysql doing stupid thing
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What changed?
Rewrite this query to use simple boolean expressions instead of tuple comparison.
Why?
For some reason mysql ends up using a full scan for this query even though the explain query plan looks reasonable.
How did you test it?
Tested with pre-release build on pipelines.
Potential risks
Is hotfix candidate?
yes