| From: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
|---|---|
| To: | pgsql-bugs(at)postgresql(dot)org |
| Cc: | 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 12:35:29 |
| Message-ID: | 200907171535.29504.peter_e@gmx.net |
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| Lists: | pgsql-bugs |
On Friday 17 July 2009 12:45:47 Mikael Krantz wrote:
> It might be that your column may be NULL as well as TRUE or FALSE. I
> am no expert in this matter though.
Nulls also need to be considered when attempting to substitute purportedly
equivalent clauses. But in this case it wouldn't actually matter, because
WHERE foo <> TRUE
and
WHERE foo = false
would both omit the row if foo is null. Both expressions only return true if
foo has the value "false". But again, this is data type specific knowledge.
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