Chris Velevitch wrote:
On 2/27/06, Russell Smith <mr-russ@xxxxxxxxxx> wrote:
Not necessarily. How many rows are there in the table at the moment.
If pg uses and index, it first has to get the index page, then get the
heap page. So if you have a small number of blocks in the heap it's
actually cheaper to just scan the heap. I would guess the heap is small
by the fact that the seq scan only find one row, and finds it in 46.32
units. The row width isn't high either and that means you get good
block packing. Probably 80-100 row's per block.
It's about 200 records.
Are you saying that the strategy pg uses is dynamic, in that as the
size of the table grows the strategy changes?
Yes, it does.
For 200 rows, it's just as quick for it to look at every row. If you
have 20,000 - then that's a different case.
--
Postgresql & php tutorials
http://www.designmagick.com/
