isTempNamespaceInUse() is incorrect with its handling of MyBackendId

Michael Paquier <[email protected]> Mon, 13 Jan 2020 18:37:03 +0900

Newsgroups	gmane.comp.db.postgresql.devel.general
Message-ID	<[email protected]>

Hi all,

While reviewing some code in namespace.c, I have bumped into the
following issue introduced by 246a6c8:
diff --git a/src/backend/catalog/namespace.c
b/src/backend/catalog/namespace.c
index c82f9fc4b5..e70243a008 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -3235,8 +3235,8 @@ isTempNamespaceInUse(Oid namespaceId)

    backendId = GetTempNamespaceBackendId(namespaceId);

-   if (backendId == InvalidBackendId ||
-       backendId == MyBackendId)
+   /* No such temporary namespace? */
+   if (backendId == InvalidBackendId)
        return false;

The current logic of isTempNamespaceInUse() would cause a session
calling the routine to return always false if trying to check if its
own temporary session is in use, but that's incorrect.  It is actually
safe to remove the check on MyBackendId as the code would fall back on
a check equivalent to MyProc->tempNamespaceId a bit down as per the
attached, so let's fix it.

Thoughts?
--
Michael

temp-schema-use.patch (text/x-diff, 500 B)

diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index c82f9fc4b5..e70243a008 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -3235,8 +3235,8 @@ isTempNamespaceInUse(Oid namespaceId)
 
 	backendId = GetTempNamespaceBackendId(namespaceId);
 
-	if (backendId == InvalidBackendId ||
-		backendId == MyBackendId)
+	/* No such temporary namespace? */
+	if (backendId == InvalidBackendId)
 		return false;
 
 	/* Is the backend alive? */

signature.asc (application/pgp-signature, 833 B)