Re: explain doubt

Luca Ferrari <fluca1978@infinito.it> writes:
> Now, what is the .35 in the cost of the bitmap index scan nodes?

If you're going to get picky about second-order cost components,
it's time to start reading the source code:


http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/optimizer/path/costsize.c;h=480c1b7425ce66a02e2e10711359143ea7ffe59c;hb=HEAD#l218

http://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/utils/adt/selfuncs.c;h=95e46276f0a8911758f4ec02b993193bf55eee15;hb=HEAD#l6087

The short answer though is that this is probably coming from CPU cost
components not disk-access components.

            regards, tom lane