Fix performance issue by using LATERAL in group notification CTE #31123
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renchap
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The CTE used
CROSS JOINinstead of aJOIN LATERAL, meaning that thenotificationsquery could not use the (single-item) working table for quick filtering, and had to filter and limit a posteriori, causing a lot of extra work.Unfortunately, it does not seem ActiveRecord exposes
LATERAL, so we have to work around witharel. Using theFROM foo, LATERAL (SELECT …)allows keepingarelusage to a minimal.