| From: | Shiby Thomas <sthomas(at)cise(dot)ufl(dot)edu> |
|---|---|
| To: | The Hermit Hacker <scrappy(at)hub(dot)org> |
| Cc: | "Vadim B(dot) Mikheev" <vadim(at)sable(dot)krasnoyarsk(dot)su>, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] Execution time. |
| Date: | 1998-02-04 18:07:01 |
| Message-ID: | 199802041807.NAA12522@cise.ufl.edu |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | 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.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Julia Anne Case | 1998-02-04 18:19:29 | Re: [HACKERS] connection troubles |
| Previous Message | Bruce Momjian | 1998-02-04 17:58:37 | Re: [HACKERS] Hi |