Re: [HACKERS] Execution time.
От | Shiby Thomas |
---|---|
Тема | Re: [HACKERS] Execution time. |
Дата | |
Msg-id | 199802041807.NAA12522@cise.ufl.edu обсуждение исходный текст |
Ответ на | Re: [HACKERS] Execution time. (The Hermit Hacker <scrappy@hub.org>) |
Список | pgsql-hackers |
=> > Is the size of the hash bucket dependent on the number of buffers available ? => > If so, with -B 30000, it might create huge hash buckets and hence the => > hash join could degenerate to a nested loops join. Is that possible -- just => > checking. What could be good values for -B and -S. The largest table I am => > joining is about 60M => => My production server runs with a -B 256, and a -S 10240 => => With less buffers, it is giving "hash table out of memory" error. I ran with -B 512 AGG :c=435416.5312 :s=0 :w=0 l: GROUP :c=435416.5312 :s=0 :w=0 l: SORT :c=435416.5312 :s=0 :w=0 l: HASHJOIN :c=435416.5312 :s=305715 :w=16 l: SEQSCAN :c=36107.7500 :s=917144 :w=8 ( t1 ) r: HASH :c=0.0000 :s=0 :w=0 l: SEQSCAN :c=36107.7500 :s=917144 :w=8 ( t1 ) ERROR: hash table out of memory. Use -B parameter to increase buffers.
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