2008/6/28 Adam Rich <adam(dot)r(at)sbcglobal(dot)net>:
> > This is not wrong, or at least not obviously wrong. A full-table
> > indexscan is often slower than seqscan-and-sort. If the particular
> > case is wrong for you, you need to look at adjusting the planner's
> > cost parameters to match your environment. But you didn't provide any
> > evidence that the chosen plan is actually worse than the alternative
> > ...
> I think I understand what Bob's getting at when he mentions blocking.
> The seqscan-and-sort would return the last record faster, but the
> indexscan returns the first record faster. If you're iterating
> through the records via a cursor, the indexscan behavior would be
> more desirable. You could get the initial rows back without waiting
> for all 130 million to be fetched and sorted.
> In oracle, there is a first-rows vs. all-rows query hint for this sort
> of thing.
Yes, that's exactly what I mean. I've already tried your suggestion (set
enable_seqscan to off) with no luck.
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