At Thu, 13 May 2021 13:26:37 +0900 (JST), Kyotaro Horiguchi <horikyota....@gmail.com> wrote in > At Thu, 13 May 2021 12:11:12 +0900 (JST), Kyotaro Horiguchi > <horikyota....@gmail.com> wrote in > > As the result, even if we take the DLL approach, still not need to > > split out the query-id provider part. By the following config: > > > > > query_id_provider = 'pg_stat_statements' > > > > the core can obtain the entrypoint of, say, "_PG_calculate_query_id" > > to call it. And it can be of another module. > > > > It seems like the only problem doing that is we don't have a means to > > call per-process intializer for a preload libralies. > > So this is a crude PoC of that. > > pg_stat_statemnts defines its own query-id provider function in > pg_stat_statements which calls in-core DefaultJumbeQuery (end emits a > log line). > > If server started with query_id_provider='auto' and pg_stat_statements > is not loaded, pg_stat_activity.query_id is null. > > If query_id_provider='auto' and pg_stat_statements is loaded, > pg_stat_activity.query_id is filled in with a query id. > > If query_id_provider='default' or 'pg_stat_statements' and > pg_stat_statements is not loaded, pg_stat_activity.query_id is filled > in with a query id. > > If query_id_provider='none' and pg_stat_statements is loaded, it > complains as "query id provider is not available" and refuss to start. > > If showing the variable, it shows the real provider name instead of > the setting in postgresql.conf.
The change contains needless things that tries to handle per-backend change case, so it would be simpler assuming we don't want on-the-fly change of provider (and I believe so since that change surely causes inconsistency) regards. -- Kyotaro Horiguchi NTT Open Source Software Center
