To: Ron Mayer <rm_pg@cheapcomplexdevices.com>
cc: Oleg Bartunov <oleg@sai.msu.su>, Teodor Sigaev <teodor@sigaev.ru>,
	pgsql-performance@postgreSQL.org
Subject: Re: Extremely slow intarray index creation and inserts. 
In-reply-to: <49BFEBD3.4000006@cheapcomplexdevices.com> 
References: <49BFD950.5040905@cheapcomplexdevices.com>
	<49BFEBD3.4000006@cheapcomplexdevices.com>
Comments: In-reply-to Ron Mayer <rm_pg@cheapcomplexdevices.com>
	message dated "Tue, 17 Mar 2009 11:28:35 -0700"
Date: Tue, 17 Mar 2009 23:24:59 -0400
Message-ID: <1804.1237346699@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Ron Mayer <rm_pg@cheapcomplexdevices.com> writes:
> vm=# create index "gist70000" on tmp_intarray_test using GIST (my_int_array gist__int_ops);
> CREATE INDEX
> Time: 2069836.856 ms

> Is that expected, or does it sound like a bug to take over
> half an hour to index 70000 rows of mostly 5 and 6-element
> integer arrays?

I poked at this example with oprofile.  It's entirely CPU-bound AFAICT,
and the CPU utilization is approximately

	55%	g_int_compress
	35%	memmove/memcpy (difficult to distinguish these)
	 1%	pg_qsort
	<1%	anything else

Probably need to look at reducing the number of calls to g_int_compress
... it must be getting called a whole lot more than once per new index
entry, and I wonder why that should need to be.

			regards, tom lane