[Pgpool-general] White and blacklist of function

[Tatsuo Ishii]

Hi Guillaume,

It was nice to see you in Paris..

> This won't be easy to do. Let's say you have this query :
> 
> SELECT function_which_writes(), function_which_doesnt_write;
> 
> It fails with an error indicating that one tried to write, which
> function is the culprit? pgpool-II can't guess that.

Actually it would be able to guess:

test=# select nextval('t1_i_seq'), upper('foo');
ERROR:  cannot execute nextval() in a read-only transaction

However I tend to think parsing the error message is not easy and am
not sure it worth the trouble.

> Moreover, it would deny the capacity to load balance explicit transactions.

Can you explain more?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp