Without index: 1.140 ms
With index: 1.400 ms
With default_statistic_targer = 200:   1.800 ms




Can I just check that 1.800ms means 1.8 secs (You're using . as the thousands separator)?


If it means 1.8ms then frankly the times are too short to mean anything without running them 100 times and averaging.



It mean 1.8 ms and that execution time is sticky to that value even with 1000 times.

Given the almost irrelvant difference in the speed of those queries, I'd say that with the stats so high, postgres simply takes longer to check the statistics to come to the same conclusion. ie. it has to loop over 200 rows instead of just 10.


Chris


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