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Reading explain plans- row estimates/actuals on lower nodes vs nextlevel up - Mailing list pgsql-performance

From Michael Lewis
Subject Reading explain plans- row estimates/actuals on lower nodes vs nextlevel up
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Msg-id CAHOFxGo1UAF45F_fdZML1QKmSjjvN_npLx52yQv7NV6Xk=COJg@mail.gmail.com
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Responses Re: Reading explain plans- row estimates/actuals on lower nodes vsnext level up
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https://explain.depesz.com/s/Caa5

I am looking at this explain analyze output and seeing a nested loop towards the lowest levels with pretty bad estimate vs actual (2.3k vs 99k), but the things that feed that nested loop seem like the estimates are rather close (index scans with 11 estimated vs 30 actual and 3350 vs 3320)... why does the higher node have such a different estimate vs actual ratio? 


Michael Lewis  |  Software Engineer
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