From 385366426511399a91da327c0f04765bbcfd5322 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 27 Sep 2022 11:47:12 -0400 Subject: Introduce GUC_NO_RESET flag. Previously, the transaction-property GUCs such as transaction_isolation could be reset after starting a transaction, because we marked them as GUC_NO_RESET_ALL but still allowed a targeted RESET. That leads to assertion failures or worse, because those properties aren't supposed to change after we've acquired a transaction snapshot. There are some NO_RESET_ALL variables for which RESET is okay, so we can't just redefine the semantics of that flag. Instead introduce a separate GUC_NO_RESET flag. Mark "seed", as well as the transaction property GUCs, as GUC_NO_RESET. We have to disallow GUC_ACTION_SAVE as well as straight RESET, because otherwise a function having a "SET transaction_isolation" clause can still break things: the end-of-function restore action is equivalent to a RESET. No back-patch, as it's conceivable that someone is doing something this patch will forbid (like resetting one of these GUCs at transaction start, or "CREATE FUNCTION ... SET transaction_read_only = 1") and not running into problems with it today. Given how long we've had this issue and not noticed, the side effects in non-assert builds can't be too serious. Per bug #17385 from Andrew Bille. Masahiko Sawada Discussion: https://postgr.es/m/17385-9ee529fb091f0ce5@postgresql.org --- src/backend/utils/misc/guc_funcs.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'src/backend/utils/misc/guc_funcs.c') diff --git a/src/backend/utils/misc/guc_funcs.c b/src/backend/utils/misc/guc_funcs.c index 3d2df18659b..ffc71726f91 100644 --- a/src/backend/utils/misc/guc_funcs.c +++ b/src/backend/utils/misc/guc_funcs.c @@ -141,9 +141,6 @@ ExecSetVariableStmt(VariableSetStmt *stmt, bool isTopLevel) WarnNoTransactionBlock(isTopLevel, "SET LOCAL"); /* fall through */ case VAR_RESET: - if (strcmp(stmt->name, "transaction_isolation") == 0) - WarnNoTransactionBlock(isTopLevel, "RESET TRANSACTION"); - (void) set_config_option(stmt->name, NULL, (superuser() ? PGC_SUSET : PGC_USERSET), @@ -539,7 +536,7 @@ ShowAllGUCConfig(DestReceiver *dest) Datum pg_settings_get_flags(PG_FUNCTION_ARGS) { -#define MAX_GUC_FLAGS 5 +#define MAX_GUC_FLAGS 6 char *varname = TextDatumGetCString(PG_GETARG_DATUM(0)); struct config_generic *record; int cnt = 0; @@ -554,6 +551,8 @@ pg_settings_get_flags(PG_FUNCTION_ARGS) if (record->flags & GUC_EXPLAIN) flags[cnt++] = CStringGetTextDatum("EXPLAIN"); + if (record->flags & GUC_NO_RESET) + flags[cnt++] = CStringGetTextDatum("NO_RESET"); if (record->flags & GUC_NO_RESET_ALL) flags[cnt++] = CStringGetTextDatum("NO_RESET_ALL"); if (record->flags & GUC_NO_SHOW_ALL) -- cgit v1.2.3