user variables in session

Hi All,

I wasn't able to find any functions which would allow me to save/fetch/remove
user variables local to pgsql session, e.g. -

1. select setvar('user variable name', 'user value');
2. select getvar('user variable name');
3. select delvar('user variable name');

Is there any way to do this with stock PostgreSQL, or via something in
contrib?

Would pgsql's HTAB with hash_create and hash_search be a good basis for a
simple C extension which would provide such feature ?

I found this to be quite useful in e.g. pl/pgsql triggers, for logging.

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Best Regards,
Igor Shevchenko