On Aug 15, 2006, at 13:55 , Peter Eisentraut wrote:
Jim C. Nasby wrote:
Meet EXPLAIN ANALYZE.
Which does no good for apps that you don't control the code on. Even
if you do control the code, you have to find a way to stick EXPLAIN
ANALYZE in front of every query, and figure out how to deal with
what's comming back.
It would not be hard to create an "auto explain analyze" mode that
implicitly runs EXPLAIN ANALYZE along with every query and logs the
result. On its face, it sounds like an obviously great idea. I just
don't see how you would put that to actual use, unless you want to
read
server logs all day long. Grepping for query duration and using the
statistics views are much more manageable tuning methods. In my view
anyway.
Also [and this has been brought up before], explain analyze doesn't
make any effort to highlight the actual discrepancies from the plan.
If it could drop an arrow or an asterisk where, for example, the
numbers are off by an order of magnitude, it would make a big
difference.
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
