From d484bc26013caedd0b210bddfcec43c2ab6fa649 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 9 Feb 2026 10:02:23 -0500 Subject: [PATCH] Add a syscache on pg_extension.oid. An upcoming patch requires this cache so that it can track updates in the pg_extension catalog. So far though, the EXTENSIONOID cache only exists in v18 and up (see 490f869d9). We can add it in older branches without an ABI break, if we are careful not to disturb the numbering of existing syscache IDs. In v16 and before, that just requires adding the new ID at the end of the hand-assigned enum list, ignoring our convention about alphabetizing the IDs. But in v17, genbki.pl enforces alphabetical order of the IDs listed in MAKE_SYSCACHE macros. We can fake it out by calling the new cache ZEXTENSIONOID. Note that adding a syscache does change the required contents of the relcache init file (pg_internal.init). But that isn't problematic since we blow those away at postmaster start for other reasons. Author: Tom Lane Reviewed-by: Noah Misch Security: CVE-2026-2004 Backpatch-through: 14-17 --- src/backend/utils/cache/syscache.c | 8 ++++++++ src/include/utils/syscache.h | 6 ++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/src/backend/utils/cache/syscache.c b/src/backend/utils/cache/syscache.c index d55277e90e9..5d1653b82c7 100644 --- a/src/backend/utils/cache/syscache.c +++ b/src/backend/utils/cache/syscache.c @@ -39,6 +39,7 @@ #include "catalog/pg_description.h" #include "catalog/pg_enum.h" #include "catalog/pg_event_trigger.h" +#include "catalog/pg_extension.h" #include "catalog/pg_foreign_data_wrapper.h" #include "catalog/pg_foreign_server.h" #include "catalog/pg_foreign_table.h" @@ -679,6 +680,13 @@ static const struct cachedesc cacheinfo[] = { KEY(Anum_pg_user_mapping_umuser, Anum_pg_user_mapping_umserver), 2 + }, + /* intentionally out of alphabetical order, to avoid an ABI break: */ + [EXTENSIONOID] = { + ExtensionRelationId, + ExtensionOidIndexId, + KEY(Anum_pg_extension_oid), + 2 } }; diff --git a/src/include/utils/syscache.h b/src/include/utils/syscache.h index 1395497e198..34b3b76aa5c 100644 --- a/src/include/utils/syscache.h +++ b/src/include/utils/syscache.h @@ -113,9 +113,11 @@ enum SysCacheIdentifier TYPENAMENSP, TYPEOID, USERMAPPINGOID, - USERMAPPINGUSERSERVER + USERMAPPINGUSERSERVER, + /* intentionally out of alphabetical order, to avoid an ABI break: */ + EXTENSIONOID -#define SysCacheSize (USERMAPPINGUSERSERVER + 1) +#define SysCacheSize (EXTENSIONOID + 1) }; extern void InitCatalogCache(void);