Re: [HACKERS] Re: type coersion (was OR clause status)

From: Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
To: lockhart(at)alumni(dot)caltech(dot)edu (Thomas G(dot) Lockhart)
Cc: tgl(at)sss(dot)pgh(dot)pa(dot)us, hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] Re: type coersion (was OR clause status)
Date: 1998-08-09 23:33:59
Message-ID: 199808092333.TAA21384@candle.pha.pa.us
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> > > 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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