Clean up handling of XactReadOnly and RecoveryInProgress checks.

Add some checks that seem logically necessary, in particular let's make
real sure that HS slave sessions cannot create temp tables.  (If they did
they would think that temp tables belonging to the master's session with
the same BackendId were theirs.  We *must* not allow myTempNamespace to
become set in a slave session.)

Change setval() and nextval() so that they are only allowed on temp sequences
in a read-only transaction.  This seems consistent with what we allow for
table modifications in read-only transactions.  Since an HS slave can't have a
temp sequence, this also provides a nicer cure for the setval PANIC reported
by Erik Rijkers.

Make the error messages more uniform, and have them mention the specific
command being complained of.  This seems worth the trifling amount of extra
code, since people are likely to see such messages a lot more than before.

1 files changed, 10 insertions, 11 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index bb783123127..20d59f9a8c9 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.346 2010/02/09 21:43:30 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.347 2010/02/20 21:24:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,6 +50,7 @@
 #include "storage/bufmgr.h"
 #include "storage/lmgr.h"
 #include "storage/smgr.h"
+#include "tcop/utility.h"
 #include "utils/acl.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
@@ -568,6 +569,10 @@ ExecCheckRTEPerms(RangeTblEntry *rte)
 
 /*
  * Check that the query does not imply any writes to non-temp tables.
+ *
+ * Note: in a Hot Standby slave this would need to reject writes to temp
+ * tables as well; but an HS slave can't have created any temp tables
+ * in the first place, so no need to check that.
  */
 static void
 ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
@@ -577,10 +582,11 @@ ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 	/*
 	 * CREATE TABLE AS or SELECT INTO?
 	 *
-	 * XXX should we allow this if the destination is temp?
+	 * XXX should we allow this if the destination is temp?  Considering
+	 * that it would still require catalog changes, probably not.
 	 */
 	if (plannedstmt->intoClause != NULL)
-		goto fail;
+		PreventCommandIfReadOnly(CreateCommandTag((Node *) plannedstmt));
 
 	/* Fail if write permissions are requested on any non-temp table */
 	foreach(l, plannedstmt->rtable)
@@ -596,15 +602,8 @@ ExecCheckXactReadOnly(PlannedStmt *plannedstmt)
 		if (isTempNamespace(get_rel_namespace(rte->relid)))
 			continue;
 
-		goto fail;
+		PreventCommandIfReadOnly(CreateCommandTag((Node *) plannedstmt));
 	}
-
-	return;
-
-fail:
-	ereport(ERROR,
-			(errcode(ERRCODE_READ_ONLY_SQL_TRANSACTION),
-			 errmsg("transaction is read-only")));
 }