From afb68b0e7eda8c86ca0d2994c2499f25a46655a0 Mon Sep 17 00:00:00 2001 From: Konstantin Knizhnik Date: Tue, 13 Aug 2024 15:07:24 +0300 Subject: [PATCH] Report search_path to make it possible to use it in pgbouncer track_extra_parameters (#8303) ## Problem When pooled connections are used, session semantic its not preserved, including GUC settings. Many customers have particular problem with setting search_path. But pgbouncer 1.20 has `track_extra_parameters` settings which allows to track parameters included in startup package which are reported by Postgres. Postgres has [an official list of parameters that it reports to the client](https://www.postgresql.org/docs/15/protocol-flow.html#PROTOCOL-ASYNC). This PR makes Postgres also report `search_path` and so allows to include it in `track_extra_parameters`. ## Summary of changes Set GUC_REPORT flag for `search_path`. ## Checklist before requesting a review - [ ] I have performed a self-review of my code. - [ ] If it is a core feature, I have added thorough tests. - [ ] Do we need to implement analytics? if so did you add the relevant metrics to the dashboard? - [ ] If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section. ## Checklist before merging - [ ] Do not forget to reformat commit message to not include the above checklist --------- Co-authored-by: Konstantin Knizhnik --- pgxn/neon/neon.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/pgxn/neon/neon.c b/pgxn/neon/neon.c index 6afca61fae..784d0f1da3 100644 --- a/pgxn/neon/neon.c +++ b/pgxn/neon/neon.c @@ -32,6 +32,7 @@ #include "utils/builtins.h" #include "utils/pg_lsn.h" #include "utils/guc.h" +#include "utils/guc_tables.h" #include "utils/wait_event.h" #include "extension_server.h" @@ -584,6 +585,40 @@ RestoreRunningXactsFromClog(CheckPoint *checkpoint, TransactionId **xids, int *n return false; } + +/* + * pgbouncer is able to track GUCs reported by Postgres. + * But most parameters cannot be tracked this way. The only parameters that can be tracked are ones + * that Postgres reports to the client. Unfortunately `search_path` is not reported by Postgres: + * https://www.postgresql.org/message-id/flat/CAGECzQQ6xFcgrg%2Be0p9mCumtK362TiA6vTiiZKoYbS8OXggwuQ%40mail.gmail.com#be4bfd7a9cf1f0633bdb2d1790a0a1be + * This code sets GUC_REPORT flag for `search_path`making it possible to include it in + * pgbouncer's `track_extra_parameters` list. + * + * This code is inspired by how the Citus extension does this, see + * https://github.com/citusdata/citus/blob/2a263fe69a707d16ef24378f7650742386b0968f/src/backend/distributed/shared_library_init.c#L2694 + */ +static void +ReportSearchPath(void) +{ +#if PG_VERSION_NUM >= 160000 + int nGucs = 0; + struct config_generic **gucs = get_guc_variables(&nGucs); +#else + struct config_generic **gucs = get_guc_variables(); + int nGucs = GetNumConfigOptions(); +#endif + + for (int i = 0; i < nGucs; i++) + { + struct config_generic *guc = (struct config_generic *) gucs[i]; + + if (strcmp(guc->name, "search_path") == 0) + { + guc->flags |= GUC_REPORT; + } + } +} + void _PG_init(void) { @@ -627,6 +662,8 @@ _PG_init(void) * extension was loaded will be removed. */ EmitWarningsOnPlaceholders("neon"); + + ReportSearchPath(); } PG_FUNCTION_INFO_V1(pg_cluster_size);