Re: Synchronized scans

Jeff Davis <pgsql(at)j-davis(dot)com> writes:
> The problem is, I think people would be more frustrated by 1 in 1000
> queries starting the scan in the wrong place because a hint was deleted,

Yeah --- various people have been complaining recently about how we have
good average performance and bad worst case, and this behavior would
definitely be more of the same. So I'm kind of backing away from the
idea of deleting the hint. But if we could change the hint behavior to
say "start reading here", successive short LIMITed reads would all start
reading from the same point, which fixes both my reproducibility concern
and Heikki's original point about being able to re-use cached data.
You'd only get into the irreproducible behavior if the LIMIT was larger
than the amount of data scanned between hint updates.

regards, tom lane