Re: about explain analyze

Teodor Sigaev <teodor(at)sigaev(dot)ru> writes:
> Tom, I am afraid that I don't understand. My first example:
> wow=# explain analyze select max(click.accesses) from click;
> QUERY PLAN
> -----------------------------------------------------------------------------------------------------------------
> Aggregate (cost=1103.70..1103.70 rows=1 width=8) (actual
> time=289.391..289.393 rows=1 loops=1)
> -> Seq Scan on click (cost=0.00..971.36 rows=52936 width=8) (actual
> time=0.013..133.943 rows=52936 loops=1)
> Total runtime: 289.498 ms
> (3 rows)

> Time: 290,695 ms

> select max() returns only one row... If you mean rows in Seq Scan than
> gettimeofday was called (52936+1)*2. Huge value :(

Right, that many times at the Seq Scan plan node, and (1+1)*2 more times
at the Aggregate node.

regards, tom lane