SELECT FOR UPDATE should never be cached about django-cachalot HOT 7 CLOSED

@jklardie You’re right, thanks for the detailed report. I vaguely assumed no-one would execute two times the same SELECT FOR UPDATE, but it was a bad assumption. I’ll soon release a new version with this fixed!

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Fixed by c5d5ee7.

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I can vouch for this. We ran into concurrency issues on our production environment. Not caching select_for_update like described by OP fixed this.

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FYI: in my system this occurs where such queries are triggered via Ajax requests. In environments where the user has bad connection, multiple requests sometimes get stacked and reach our server simultaneously.

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@jklardie: Why did you add select_for_update_nowait? From what I understand, it cannot be True without select_for_update (see lines 828-840 of query.py).

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You are right, I was not aware of this. I wrongly assumed Django handled them exclusively. I will update my initial post.

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Version 1.4.0 is out, including this fix!

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