On Mon, Mar 19, 2007 at 04:40:52PM +0300, Teodor Sigaev wrote:
> >Right, except that flag is per operator in operator class, and what I'm
> >proposing is that the index could pass a flag per tuple in the scan.
>
> That might make sense even for GiST. Sometimes complex compressions is used
> in GiST opclasses. If indexing value is rather small then it's stored in
> index as is, but large value is compressed with lossy techniques. So, GiST
> might return a tuple which is allowed to not recheck.
Given that rechecking requires Expr and state structures, maybe it would
be easier to make the operators RECHECK so the planner does the right
thing now, but make a flag that tells the index scan *not* to recheck
this tuple. That would seem slightly less work and fit better with the
existing code. (In other words, it's an optimisation rather than a big
change).
Have a nice day,
--
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.