Re: [HACKERS] Re: type coersion (was OR clause status) - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Re: type coersion (was OR clause status)
Date
Msg-id 199808092333.TAA21384@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] Re: type coersion (was OR clause status)  ("Thomas G. Lockhart" <lockhart@alumni.caltech.edu>)
List pgsql-hackers
> > > Yes the handling does matter *in general*...
> > This is all a good point. I wonder whether it wouldn't help to make
> > the parser's initial assignment of types to constants depend on how
> > big the constants are.
>
> I agree that there is something to fix, including both of the indexing
> example cases you are following. I've been seeing this as an opportunity
> to fix sub-optimal utilization of indices, and my recent changes to
> enhance the type conversion capabilities in the parser just put the
> index handling in a harsher light.
>
> If we come near release time, and no one has been able to penetrate the
> index handling (to fix cases as simple as "where x = 1 + 1" which have
> never worked) the we could fairly easily go back into the parser and
> brute-force some non-general workarounds to get the few "worse than
> before" cases hacked around.
>
> If we _can_ get the index handling to work more generally, then we have
> substantially enhanced the overall capabilities of Postgres.
>
> So far, I haven't seen cases where the parser has tried to do "the wrong
> thing", only cases where "the right thing" causes the index handling to
> miss the boat...

I have found what is happening in the optimizer, and will explain soon.

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