On Thu, May 13, 2021 at 08:52:36AM +0800, Julien Rouhaud wrote: > On Wed, May 12, 2021 at 08:36:18PM -0400, Bruce Momjian wrote: > > The problem with compute_query_id=auto is that there is no way to know > > if the query id is actually enabled, unless you guess from the installed > > extensions, or we add another variable to report that, and maybe another > > variable to control the provier, unless we require turning > > compute_query_id=off if you are using custom query id computation. What > > if it is auto, and pg_stat_statments is installed, and you want to use a > > custom query id computation --- what happens? As you can see, this is > > all becoming very complicated. > > Well, as implemented you can get the value of compute_query_id, and if it's > still "auto" then it's not enabled as calling queryIdWanted() would turn it to > on. I agree that it's not ideal but you have a way to know. We could > document > that auto means that it's set to auto and no one asked to automatically > enabled > it.
Wow, so the extension changes it? How do we record the "source" of that change? Do we have other GUCs that do that? > Or you can just do e.g. > > SELECT query_id FROM pg_stat_activity WHERE pid = pg_backend_pid(); > > and see if you have a query_id or not. True. > If you want to use third-party modules, they you have to explicitly disable > compute_query_id. If you don't, every query execution will raise an error as > we documented that third-party modules should error out if they see that a > query_id is already generated. Such module could also explicitly check that > compute_query_id is off and also raise an error if that's not the case. OK. > > I think we might be just as well to go with compute_query_id=on/off, and > > just complain loudly from CREATE EXTENSION, or in the server logs on > > server start via shared_preload_libraries, or when querying > > pg_stat_statements system view. We simply say to change > > compute_query_id=on or to provide a custom query id implementation. > > I'm not opposed to that, but it was already suggested and apparently people > didn't like that approach. Also probably true. -- Bruce Momjian <br...@momjian.us> https://momjian.us EDB https://enterprisedb.com If only the physical world exists, free will is an illusion.
