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do temporary tables have hint bits? 2+ messages / 2 participants [nested] [flat]
* do temporary tables have hint bits? @ 2010-11-13 13:53 Jon Nelson <jnelson+pgsql@jamponi.net> 0 siblings, 1 reply; 2+ messages in thread From: Jon Nelson @ 2010-11-13 13:53 UTC (permalink / raw) To: pgsql-performance I was doing some testing with temporary tables using this sql: begin; select pg_sleep(30); create temporary TABLE foo (a int, b int, c int, d text); insert into foo SELECT (x%1000) AS a,(x%1001) AS b, (x % 650) as c, '' as d FROM generate_series( 1, 1000000 ) AS x; -- create temporary TABLE foo AS SELECT (x%1000) AS a,(x%1001) AS b, (x % 650) as c, '' as d FROM generate_series( 1, 1000000 ) AS x; select count(1) from foo; While it was in pg_sleep, I would attach to the backend process with strace. I observed a few things that I don't yet understand, but one thing I did notice was an I/O pattern (following the count(1)) that seemed to suggest that the table was getting its hint bits set. I thought hint bits were just for the mvcc side of things? If this is a temporary table, is there any need or benefit to setting hint bits? -- Jon ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: do temporary tables have hint bits? @ 2010-11-13 14:57 Tom Lane <tgl@sss.pgh.pa.us> parent: Jon Nelson <jnelson+pgsql@jamponi.net> 0 siblings, 0 replies; 2+ messages in thread From: Tom Lane @ 2010-11-13 14:57 UTC (permalink / raw) To: Jon Nelson <jnelson+pgsql@jamponi.net>; +Cc: pgsql-performance Yes. regards, tom lane ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2010-11-13 14:57 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2010-11-13 13:53 do temporary tables have hint bits? Jon Nelson <jnelson+pgsql@jamponi.net> 2010-11-13 14:57 ` Tom Lane <tgl@sss.pgh.pa.us>
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