#24609: Concat on MySQL doesn't need the coalesce step
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Reporter: adamchainz | Owner: nobody
Type: Cleanup/optimization | Status: new
Component: Database layer (models, ORM) | Version: 1.8
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 1
Easy pickings: 0 | UI/UX: 0
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The new Concat database function calls ConcatPair which does a coalesce
around each argument with the empty string on sqlite and MySQL.
MySQL's CONCAT *does* return NULL if any argument is NULL, however it has
a very similar function, CONCAT_WS that just silently skips NULLs.
Therefore it can be used rather than unnecessary COALESCE calls:
https://dev.mysql.com/doc/refman/5.5/en/string-functions.html
#function_concat-ws
I've implemented this in a patch - it's not a big change.
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Ticket URL: <https://code.djangoproject.com/ticket/24609>
Django <https://code.djangoproject.com/>
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