Re: explain analyze reports 20x more time than actual

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

"Craig A. James" <cjames(at)modgraph-usa(dot)com> writes:
> I have a query that needs to run faster, with the obvious solution
> being to add an index.  But to confirm this, I ran explain analyze.
> When I run the actual query, it consistently takes 6-7 seconds by the
> wall clock.  My application with a "verbose" mode enabled reports 6.6
> seconds consistently.  However, when I run EXPLAIN ANALYZE, it takes
> 120 seconds!

See recent discussions --- if you've got duff PC hardware, it seems that
reading the clock takes forever :-(.  In this case I'd assume that the
cost of the seqscan (11497361 rows returned) is being overstated because
of the 2*11497361 gettimeofday calls involved.

			regards, tom lane