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
<command>SHOW ALL</command> commands.
</entry>
</row>
+ <row>
+ <entry><literal>NO_RESET</literal></entry>
+ <entry>Parameters with this flag do not support
+ <command>RESET</command> commands.
+ </entry>
+ </row>
<row>
<entry><literal>NO_RESET_ALL</literal></entry>
<entry>Parameters with this flag are excluded from
}
}
+ /* Disallow resetting and saving GUC_NO_RESET values */
+ if (record->flags & GUC_NO_RESET)
+ {
+ if (value == NULL)
+ {
+ ereport(elevel,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("parameter \"%s\" cannot be reset", name)));
+ return 0;
+ }
+ if (action == GUC_ACTION_SAVE)
+ {
+ ereport(elevel,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("parameter \"%s\" cannot be set locally in functions",
+ name)));
+ return 0;
+ }
+ }
+
/*
* Should we set reset/stacked values? (If so, the behavior is not
* transactional.) This is done either when we get a default value from
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),
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;
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)
{"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,
{"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,
{"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,
{"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,
#define GUC_LIST_INPUT 0x0001 /* input can be list format */
#define GUC_LIST_QUOTE 0x0002 /* double-quote list elements */
#define GUC_NO_SHOW_ALL 0x0004 /* exclude from SHOW ALL */
+#define GUC_NO_RESET 0x400000 /* disallow RESET and SAVE */
#define GUC_NO_RESET_ALL 0x0008 /* exclude from RESET ALL */
#define GUC_REPORT 0x0010 /* auto-report changes to client */
#define GUC_NOT_IN_SAMPLE 0x0020 /* not in postgresql.conf.sample */
PERFORM 1;
RAISE INFO '%', current_setting('transaction_isolation');
COMMIT;
- SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
- RESET TRANSACTION ISOLATION LEVEL;
+ SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
PERFORM 1;
RAISE INFO '%', current_setting('transaction_isolation');
COMMIT;
$$;
INFO: read committed
INFO: repeatable read
-INFO: read committed
+INFO: serializable
-- error cases
DO LANGUAGE plpgsql $$
BEGIN
PERFORM 1;
RAISE INFO '%', current_setting('transaction_isolation');
COMMIT;
- SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
- RESET TRANSACTION ISOLATION LEVEL;
+ SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
PERFORM 1;
RAISE INFO '%', current_setting('transaction_isolation');
COMMIT;
CREATE TABLE tab_settings_flags AS SELECT name, category,
'EXPLAIN' = ANY(flags) AS explain,
+ 'NO_RESET' = ANY(flags) AS no_reset,
'NO_RESET_ALL' = ANY(flags) AS no_reset_all,
'NO_SHOW_ALL' = ANY(flags) AS no_show_all,
'NOT_IN_SAMPLE' = ANY(flags) AS not_in_sample,
------
(0 rows)
+-- NO_RESET implies NO_RESET_ALL.
+SELECT name FROM tab_settings_flags
+ WHERE no_reset AND NOT no_reset_all
+ ORDER BY 1;
+ name
+------
+(0 rows)
+
DROP TABLE tab_settings_flags;
777 | 777.777
(5 rows)
+-- Test that transaction characteristics cannot be reset.
+BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
+SELECT COUNT(*) FROM xacttest;
+ count
+-------
+ 5
+(1 row)
+
+RESET transaction_isolation; -- error
+ERROR: parameter "transaction_isolation" cannot be reset
+END;
+BEGIN TRANSACTION READ ONLY;
+SELECT COUNT(*) FROM xacttest;
+ count
+-------
+ 5
+(1 row)
+
+RESET transaction_read_only; -- error
+ERROR: parameter "transaction_read_only" cannot be reset
+END;
+BEGIN TRANSACTION DEFERRABLE;
+SELECT COUNT(*) FROM xacttest;
+ count
+-------
+ 5
+(1 row)
+
+RESET transaction_deferrable; -- error
+ERROR: parameter "transaction_deferrable" cannot be reset
+END;
+CREATE FUNCTION errfunc() RETURNS int LANGUAGE SQL AS 'SELECT 1'
+SET transaction_read_only = on; -- error
+ERROR: parameter "transaction_read_only" cannot be set locally in functions
-- Read-only tests
CREATE TABLE writetest (a int);
CREATE TEMPORARY TABLE temptest (a int);
SELECT pg_settings_get_flags('does_not_exist');
CREATE TABLE tab_settings_flags AS SELECT name, category,
'EXPLAIN' = ANY(flags) AS explain,
+ 'NO_RESET' = ANY(flags) AS no_reset,
'NO_RESET_ALL' = ANY(flags) AS no_reset_all,
'NO_SHOW_ALL' = ANY(flags) AS no_show_all,
'NOT_IN_SAMPLE' = ANY(flags) AS not_in_sample,
SELECT name FROM tab_settings_flags
WHERE no_show_all AND NOT not_in_sample
ORDER BY 1;
+-- NO_RESET implies NO_RESET_ALL.
+SELECT name FROM tab_settings_flags
+ WHERE no_reset AND NOT no_reset_all
+ ORDER BY 1;
DROP TABLE tab_settings_flags;
-- should have members again
SELECT * FROM xacttest;
+-- Test that transaction characteristics cannot be reset.
+BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
+SELECT COUNT(*) FROM xacttest;
+RESET transaction_isolation; -- error
+END;
+
+BEGIN TRANSACTION READ ONLY;
+SELECT COUNT(*) FROM xacttest;
+RESET transaction_read_only; -- error
+END;
+
+BEGIN TRANSACTION DEFERRABLE;
+SELECT COUNT(*) FROM xacttest;
+RESET transaction_deferrable; -- error
+END;
+
+CREATE FUNCTION errfunc() RETURNS int LANGUAGE SQL AS 'SELECT 1'
+SET transaction_read_only = on; -- error
-- Read-only tests
projects / postgresql-pgindent.git / commitdiff