Convert REPLACE INTO -> INSERT ON DUPLICATE KEY UPDATE (MySQL) #601
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shawnhathaway
changed the title
alexshtin
reviewed
Jul 24, 2020
| return mdb.conn.Exec(q, args...) | ||
| } | ||
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| func expandBatchInsertQuery(q string, rowCount int) string { |
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I hope you covered this with tests (at least existing ones).
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Yes this was covered by existing tests atleast and will fail without this :) It took way too long to make named batch inserts work given sqlx bug of inserting artifacts at the end of the query.
alexshtin
approved these changes
Jul 24, 2020
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What changed?
Converted all REPLACE INTO usages with INSERT ON DUPLICATE KEY UPDATE semantics.
Docs - https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html
Why?
Vitess does not support REPLACE INTO with fully sharded setups as REPLACE INTO deletes and reinserts the new row, which could possibly be in another shard depending on the VIndex. INSERT ON DUPLICATE KEY UPDATE forces you to specify which columns are being updated (cannot be VIndex column) and modifies the existing row.
How did you test it?
Existing Unit Tests, Buildkite, Manual BenchTest on EKS cluster.
Potential risks
Update behavior change of REPLACE vs INSERT could bring in subtle changes in behavior, but this should not be a major issue.
Todo
This needs to be validated for Postgres, but as Postgres does not support REPLACE INTO, this may not be an issue. In any case this is a backwards compatible change. Will do in a separate PR.