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_tables.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'src/backend/utils/misc/guc_tables.c') diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index ab3140ff3af..fda3f9befb0 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -1505,7 +1505,7 @@ struct config_bool ConfigureNamesBool[] = {"transaction_read_only", PGC_USERSET, CLIENT_CONN_STATEMENT, gettext_noop("Sets the current transaction's read-only status."), NULL, - GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE + GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE }, &XactReadOnly, false, @@ -1524,7 +1524,7 @@ struct config_bool ConfigureNamesBool[] = {"transaction_deferrable", PGC_USERSET, CLIENT_CONN_STATEMENT, gettext_noop("Whether to defer a read-only serializable transaction until it can be executed with no possible serialization failures."), NULL, - GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE + GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE }, &XactDeferrable, false, @@ -3606,7 +3606,7 @@ struct config_real ConfigureNamesReal[] = {"seed", PGC_USERSET, UNGROUPED, gettext_noop("Sets the seed for random-number generation."), NULL, - GUC_NO_SHOW_ALL | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE + GUC_NO_SHOW_ALL | GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE }, &phony_random_seed, 0.0, -1.0, 1.0, @@ -4557,7 +4557,7 @@ struct config_enum ConfigureNamesEnum[] = {"transaction_isolation", PGC_USERSET, CLIENT_CONN_STATEMENT, gettext_noop("Sets the current transaction's isolation level."), NULL, - GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE + GUC_NO_RESET | GUC_NO_RESET_ALL | GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE }, &XactIsoLevel, XACT_READ_COMMITTED, isolation_level_options, -- cgit v1.2.3