stig erikson <[EMAIL PROTECTED]> writes:
> the question is simply why the planner is not smart enough to skip the bitmap
> scan if normal operation is faster.
Probably because it hasn't got good statistics about the distribution of
"bid":
> -> Bitmap Index Scan on bid_index (cost=0.00..44.51
> rows=7576 width=0) (actual time=0.137..0.137 rows=506 loops=1)
> Index Cond: (bid = 17675)
When the rowcount estimate is off by more than a factor of 10, the costs
are going to be wrong too. Try increasing the statistics target for this
table.
regards, tom lane
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TIP 5: don't forget to increase your free space map settings
