| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> |
| Cc: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it>, pgsql-sql(at)postgresql(dot)org |
| Subject: | Re: short-cutting if sum()>constant |
| Date: | 2009-12-23 16:36:31 |
| Message-ID: | 28619.1261586191@sss.pgh.pa.us |
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| Lists: | pgsql-sql |
Craig Ringer <craig(at)postnewspapers(dot)com(dot)au> writes:
> Pavel Stehule wrote:
>> these queries are executed in some special mode, but still it is more
>> expensive than C a = a + 1
> ... and may have different rules, so you can't just write a simple "map
> expressions to C equivalents" arithmetic evaluator.
Yeah. As an example, overflow is supposed to be caught in "a + 1",
unlike what would happen in C.
In principle you could map some of the builtin operators into inline
code, but it would be a great deal of work and the results would be
un-portable.
regards, tom lane
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