Re: bgwriter, inherited temp tables TODO items?

"Thomas F. O'Connell" <tfo@sitening.com> writes:
> Tom seems to come pretty close to a TODO item in his analysis in my  
> opinion. Something like:

> "Make the planner ignore temp tables of other backends when expanding  
> an inheritance list."

I've done this in CVS tip.  I'm not sure whether it should be considered
a backpatchable bug fix, though.

If you want to apply the patch locally, it's attached --- should work
fine in 8.0, but I'm not sure about 7.4 or earlier, which have slightly
different logic here.
        regards, tom lane


*** src/backend/optimizer/prep/prepunion.c.orig    Thu Jul 28 18:27:00 2005
--- src/backend/optimizer/prep/prepunion.c    Tue Aug  2 16:21:41 2005
***************
*** 22,27 ****
--- 22,28 ----   #include "access/heapam.h"
+ #include "catalog/namespace.h" #include "catalog/pg_type.h" #include "nodes/makefuncs.h" #include
"optimizer/clauses.h"
***************
*** 808,813 ****
--- 809,824 ----         Index        childRTindex;          /*
+          * It is possible that the parent table has children that are
+          * temp tables of other backends.  We cannot safely access such
+          * tables (because of buffering issues), and the best thing to do
+          * seems to be to silently ignore them.
+          */
+         if (childOID != parentOID &&
+             isOtherTempNamespace(get_rel_namespace(childOID)))
+             continue;
+ 
+         /*          * Build an RTE for the child, and attach to query's rangetable          * list. We copy most
fieldsof the parent's RTE, but replace          * relation OID, and set inh = false.
 
***************
*** 818,823 ****
--- 829,845 ----         parse->rtable = lappend(parse->rtable, childrte);         childRTindex =
list_length(parse->rtable);        inhRTIs = lappend_int(inhRTIs, childRTindex);
 
+     }
+ 
+     /*
+      * If all the children were temp tables, pretend it's a non-inheritance
+      * situation.  The duplicate RTE we added for the parent table is harmless.
+      */
+     if (list_length(inhRTIs) < 2)
+     {
+         /* Clear flag to save repeated tests if called again */
+         rte->inh = false;
+         return NIL;     }      /*