| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Cc: | pgsql-bugs(at)postgresql(dot)org, Mikael Krantz <mk(at)zigamorph(dot)se>, "Jan-Ivar Mellingen" <jan-ivar(dot)mellingen(at)alreg(dot)no> |
| Subject: | Re: Huge speed penalty using <>TRUE instead of =FALSE |
| Date: | 2009-07-17 14:21:43 |
| Message-ID: | 29292.1247840503@sss.pgh.pa.us |
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| Lists: | pgsql-bugs |
Peter Eisentraut <peter_e(at)gmx(dot)net> writes:
> ... But again, this is data type specific knowledge.
Actually, now that I think about it, the planner already has
datatype-specific knowledge about boolean equality (see
simplify_boolean_equality). It would take just a few more lines of code
there to recognize "x <> true" and "x <> false" as additional variant
spellings of the generic "x" or "NOT x" constructs. Not sure if it's
worth the trouble though; how many people really write such things?
If you really wanted to take it to extremes, you could also reduce
cases like "x > false", but that's starting to get a bit silly.
regards, tom lane
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