Portal and memory management infrastructure for extended query protocol.

Both plannable queries and utility commands are now always executed
within Portals, which have been revamped so that they can handle the
load (they used to be good only for single SELECT queries).  Restructure
code to push command-completion-tag selection logic out of postgres.c,
so that it won't have to be duplicated between simple and extended queries.
initdb forced due to addition of a field to Query nodes.

1 files changed, 51 insertions, 1 deletions

diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index 8ca7fb954f0..5d481a3f0a5 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.119 2003/04/29 22:13:10 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.120 2003/05/02 20:54:35 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1016,6 +1016,7 @@ fireRules(Query *parsetree,
 											event_qual, rt_index, event);
 
 			rule_action->querySource = qsrc;
+			rule_action->canSetTag = false;		/* might change later */
 
 			results = lappend(results, rule_action);
 		}
@@ -1181,6 +1182,9 @@ QueryRewrite(Query *parsetree)
 	List	   *querylist;
 	List	   *results = NIL;
 	List	   *l;
+	CmdType		origCmdType;
+	bool		foundOriginalQuery;
+	Query	   *lastInstead;
 
 	/*
 	 * Step 1
@@ -1235,5 +1239,51 @@ QueryRewrite(Query *parsetree)
 		results = lappend(results, query);
 	}
 
+	/*
+	 * Step 3
+	 *
+	 * Determine which, if any, of the resulting queries is supposed to set
+	 * the command-result tag; and update the canSetTag fields accordingly.
+	 *
+	 * If the original query is still in the list, it sets the command tag.
+	 * Otherwise, the last INSTEAD query of the same kind as the original
+	 * is allowed to set the tag.  (Note these rules can leave us with no
+	 * query setting the tag.  The tcop code has to cope with this by
+	 * setting up a default tag based on the original un-rewritten query.)
+	 *
+	 * The Asserts verify that at most one query in the result list is marked
+	 * canSetTag.  If we aren't checking asserts, we can fall out of the loop
+	 * as soon as we find the original query.
+	 */
+	origCmdType = parsetree->commandType;
+	foundOriginalQuery = false;
+	lastInstead = NULL;
+
+	foreach(l, results)
+	{
+		Query	   *query = (Query *) lfirst(l);
+
+		if (query->querySource == QSRC_ORIGINAL)
+		{
+			Assert(query->canSetTag);
+			Assert(!foundOriginalQuery);
+			foundOriginalQuery = true;
+#ifndef USE_ASSERT_CHECKING
+			break;
+#endif
+		}
+		else
+		{
+			Assert(!query->canSetTag);
+			if (query->commandType == origCmdType &&
+				(query->querySource == QSRC_INSTEAD_RULE ||
+				 query->querySource == QSRC_QUAL_INSTEAD_RULE))
+				lastInstead = query;
+		}
+	}
+
+	if (!foundOriginalQuery && lastInstead != NULL)
+		lastInstead->canSetTag = true;
+
 	return results;
 }