hidden errors calling a volatile function inside a stable function

Hi,

I have "PostgreSQL 8.2.4 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC)
3.4.2 (mingw-special)" on Windows OS , but I experienced the same problem on
"PostgreSQL 8.3.5, compiled by Visual C++ build 1400" too.

I attach the demo database here, to be available to test according with the
following scenario.

I found in a STABLE function, for instance "TEST_0"(), it is not allowed to
use INSERT statement. Trying this will give me the error:
ERROR: INSERT is not allowed in a non-volatile function

Same behavior is for DELETE statement (e.g. "TEST_1"()).

If I set the function to VOLATILE (as "TEST_2"() ), it works very well.

I replace DELETE and INSERT statements with a volatile function call, in
"TEST_3"(), and I call it. It works well too.

Finally I set the function as STABLE, not VOLATILE (see "TEST_4"()).

First I call:
DELETE FROM "A";

Then another call:
SELECT "TEST_4"();

I get no rosen errors, but the results are wrong (see the log results),
because "TEST_4"() doesn't see the changes made by the called function.

I find this behaviour it is very dangerous because it is completely hidden.
What do you say ?

TIA,
Sabin

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