Обсуждение: Is this useful

I found this in my mailbox.  Is it any good?

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026
Index: src/backend/executor/execMain.c
===================================================================
RCS file: /usr/local/cvsroot/pgsql/src/backend/executor/execMain.c,v
retrieving revision 1.48
diff -c -r1.48 execMain.c
*** execMain.c    1998/06/15 19:28:19    1.48
--- execMain.c    1998/07/19 03:35:49
***************
*** 522,539 ****
       *        SELECT added by daveh@insightdist.com  5/20/98 to allow
       *        ORDER/GROUP BY have an identifier missing from the target.
       */
-     if (operation == CMD_UPDATE || operation == CMD_DELETE ||
-         operation == CMD_INSERT || operation == CMD_SELECT)
      {
!         JunkFilter *j = (JunkFilter *) ExecInitJunkFilter(targetList);
!         estate->es_junkFilter = j;
!
          if (operation == CMD_SELECT)
!             tupType = j->jf_cleanTupType;
!     }
!     else
!         estate->es_junkFilter = NULL;

      /* ----------------
       *    initialize the "into" relation
       * ----------------
--- 522,559 ----
       *        SELECT added by daveh@insightdist.com  5/20/98 to allow
       *        ORDER/GROUP BY have an identifier missing from the target.
       */
      {
!         bool    junk_filter_needed = false;
!         List    *tlist;
!
          if (operation == CMD_SELECT)
!         {
!             foreach(tlist, targetList)
!             {
!                 TargetEntry    *tle = lfirst(tlist);
!
!                 if (tle->resdom->resjunk)
!                 {
!                     junk_filter_needed = true;
!                     break;
!                 }
!             }
!         }

+         if (operation == CMD_UPDATE || operation == CMD_DELETE ||
+             operation == CMD_INSERT ||
+             (operation == CMD_SELECT && junk_filter_needed))
+         {
+             JunkFilter *j = (JunkFilter *) ExecInitJunkFilter(targetList);
+             estate->es_junkFilter = j;
+
+             if (operation == CMD_SELECT)
+                 tupType = j->jf_cleanTupType;
+         }
+         else
+             estate->es_junkFilter = NULL;
+     }
+
      /* ----------------
       *    initialize the "into" relation
       * ----------------

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> I found this in my mailbox.  Is it any good?

Seems to have been done long since --- see execMain.c, lines 809 ff.

Looking at that code, I wonder if it's still doing unnecessary work.
Why would we need a junkfilter for a DELETE?  We aren't going to be
constructing output tuples, are we?
        regards, tom lane

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > I found this in my mailbox.  Is it any good?
> 
> Seems to have been done long since --- see execMain.c, lines 809 ff.
> 
> Looking at that code, I wonder if it's still doing unnecessary work.
> Why would we need a junkfilter for a DELETE?  We aren't going to be
> constructing output tuples, are we?

Good question.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026