Re: funny (cache (?)) bug in postgres (7.x tested)

RISKO Gergely wrote:
[Charset iso-8859-1,iso- unsupported, skipping...]

> Hello!
>
> I found a funny bug in postgres with c functions. (or feature??)
> Let's say we have got an function like this:
> CREATE FUNCTION hupper(text)
> RETURNS text
> AS '/fun.so'
> LANGUAGE 'c';

This is actually neither a feature, nor a bug in Postgres.
Your function is violating some coding rules.

The text argument handed into is actually residing inside the
shared buffer cache. So you're not supposed to change it!

Your function isn't safe for compressed or toasted values. If
you accidentially have big data in that column, it might
crash the backend completely.

A function returning text has to allocate the return value
with palloc().

Look into utils/adt/*.c for examples how to deal correctly
with text attributes.

Jan

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