> broadly speaking:
> *) function generates same output from inputs regardless of what's
> going on in the database, and has no side effects: IMMUTABLE
So can I say "if a function is marked IMMUTABLE, then it should never
modify database"? Is there any counter example?
> *) function reads (only) from tables, or is an immutable function in
> most senses but influenced from the GUC (or any other out of scope
> thing): STABLE
It seems if above is correct, I can say STABLE functions should never
modify databases as well.
> *) all other cases: VOLATILE (which is btw the default)
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
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