isTempNamespaceInUse() is incorrect with its handling of MyBackendId - Mailing list pgsql-hackers

From Michael Paquier
Subject isTempNamespaceInUse() is incorrect with its handling of MyBackendId
Date
Msg-id 20200113093703.GA41902@paquier.xyz
Whole thread Raw
Responses Re: isTempNamespaceInUse() is incorrect with its handling ofMyBackendId  (Julien Rouhaud <rjuju123@gmail.com>)
List pgsql-hackers
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

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