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/gcbrun |
roger2hk
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Apr 4, 2025
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@AlCutter ping :) |
mhutchinson
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Apr 10, 2025
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In our CT logs that use the PostgreSQL quota manager, we've found that in practice
ANALYZE (SKIP_LOCKED TRUE)in the count_estimate() function gets skipped a lot of the time. Removing(SKIP_LOCKED TRUE)hurts performance, because it first has to wait for a lock and then it holds that lock until theANALYZEoperation completes. For tables with a relatively small number of rows, it's actually a lot quicker to do a simpleSELECT count(1)query (whereas for large tables,SELECT count(1)is very slow). This PR implements a hybrid approach that avoids runningANALYZEwhen there are <1000 rows and avoids runningSELECT count(1)for >1000 rows. We've deployed this to our Elephant and Tiger CT logs, and it's definitely improved performance.This PR also implements a couple of minor editorial changes to the queue_leaves() and add_sequenced_leaves() functions.
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