Re: [PATCH] Improve EXPLAIN ANALYZE overhead by sampling
От | Qingqing Zhou |
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Тема | Re: [PATCH] Improve EXPLAIN ANALYZE overhead by sampling |
Дата | |
Msg-id | e41m79$292g$1@news.hub.org обсуждение исходный текст |
Ответ на | [PATCH] Improve EXPLAIN ANALYZE overhead by sampling (Martijn van Oosterhout <kleptog@svana.org>) |
Ответы |
Re: [PATCH] Improve EXPLAIN ANALYZE overhead by sampling
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Список | pgsql-patches |
"Martijn van Oosterhout" <kleptog@svana.org> wrote > > What it does behave normally for the first 50 tuples of any node, but > after that it starts sampling at ever increasing intervals, the > intervals controlled by an exponential function. > I got two questions after scanning the patch: (1) For a node with 50 loops and another one 50+10^3 loops, the first one will be measured 50 times and the second one will be measured 50+10 times? I am not sure if this is rational. (2) Will this patch instruct multinode without interval? This is because we always use ntuples=0 for multinode, so the tuplecount will not change. Maybe another way is to measure the cost of timing, then substruct it from the result - but this is a hand-waiving only so far ... Regards, Qingqing
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