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

From: "Thomas G(dot) Lockhart" <lockhart(at)alumni(dot)caltech(dot)edu>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us>
Cc: PostgreSQL-development <hackers(at)postgreSQL(dot)org>
Subject: Re: [HACKERS] Re: type coersion (was OR clause status)
Date: 1998-08-09 22:30:23
Message-ID: 35CE22FF.4B30E754@alumni.caltech.edu
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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...

- Tom

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