Alex Vandiver 6e91e326e9 deferred_work: Reduce batch size due to bad statistics. ...

PostgreSQL's estimate of the number of usermessage rows for a single
message can be wildly off, due to poor statistics generation.  This
causes this query, with 100-message batch sizes, to incorrectly
estimate millions of matched rows, causing it to perform a full-table
index scan, rather than piecemeal using the `message_id` index.

Reduce the batch size to 50, which is enough to tip in favor of a
rational query plan.

2024-03-11 09:24:59 -07:00

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