Tom Lane wrote:
And you can't just dismiss the issue of wrong cost models and say we can
get numbers anyway.
Is there a way to see more details about the cost estimates.
EXPLAIN ANALYZE seems to show the total time and rows; but not
information like how many disk pages were accessed.
I get the feeling that sometimes the number of rows is estimated
very well, but the amount of disk I/O is way off.
Sometimes the number of pages read/written is grossly
overestimated (if tables lave a lot of locally clustered data)
or underestimated if a sort barely exceeds sort_mem.
Perhaps an EXPLAN ANALYZE VERBOSE that would add info like this:
Index scan ([...]estimated 1000 pages read) (actual[...] 10 pages read)
would help track those down?
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
