| From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
|---|---|
| To: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
| Subject: | Volatility - docs vs behaviour? |
| Date: | 2014-06-30 09:24:55 |
| Message-ID: | 53B12CE7.5090506@2ndquadrant.com |
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| Lists: | pgsql-performance |
Hi all
The docs say:
"For best optimization results, you should label your functions with the
strictest volatility category that is valid for them."
http://www.postgresql.org/docs/current/interactive/xfunc-volatility.html
... but I recall discussion here suggesting that in fact IMMUTABLE
functions may not be inlined where you'd expect, e.g.
That's always seemed counter to my expectations. Am I just
misunderstanding? Tom's comment seemed to confirm what Pavel was saying.
I know STRICT can prevent inlining (unfortunately, though necessarily),
but it seems inexplicable that IMMUTABLE should. If it can, then the
documentation is wrong.
Which is it?
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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