Restructure command destination handling so that we pass around

DestReceiver pointers instead of just CommandDest values.  The DestReceiver
is made at the point where the destination is selected, rather than
deep inside the executor.  This cleans up the original kluge implementation
of tstoreReceiver.c, and makes it easy to support retrieving results
from utility statements inside portals.  Thus, you can now do fun things
like Bind and Execute a FETCH or EXPLAIN command, and it'll all work
as expected (e.g., you can Describe the portal, or use Execute's count
parameter to suspend the output partway through).  Implementation involves
stuffing the utility command's output into a Tuplestore, which would be
kind of annoying for huge output sets, but should be quite acceptable
for typical uses of utility commands.

1 files changed, 54 insertions, 10 deletions

diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index c81dd33d36a..2e040f78903 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.64 2003/05/06 00:20:31 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execTuples.c,v 1.65 2003/05/06 20:26:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -591,6 +591,49 @@ ExecTypeFromTL(List *targetList, bool hasoid)
 	return typeInfo;
 }
 
+/* ----------------------------------------------------------------
+ *		ExecCleanTypeFromTL
+ *
+ *		Same as above, but resjunk columns are omitted from the result.
+ * ----------------------------------------------------------------
+ */
+TupleDesc
+ExecCleanTypeFromTL(List *targetList, bool hasoid)
+{
+	TupleDesc	typeInfo;
+	List	   *tlitem;
+	int			len;
+	int			cleanresno;
+
+	/*
+	 * allocate a new typeInfo
+	 */
+	len = ExecCleanTargetListLength(targetList);
+	typeInfo = CreateTemplateTupleDesc(len, hasoid);
+
+	/*
+	 * scan list, generate type info for each entry
+	 */
+	cleanresno = 1;
+	foreach(tlitem, targetList)
+	{
+		TargetEntry *tle = lfirst(tlitem);
+		Resdom	   *resdom = tle->resdom;
+
+		if (resdom->resjunk)
+			continue;
+		TupleDescInitEntry(typeInfo,
+						   cleanresno++,
+						   resdom->resname,
+						   resdom->restype,
+						   resdom->restypmod,
+						   0,
+						   false);
+	}
+
+	return typeInfo;
+}
+
 /*
  * TupleDescGetSlot - Initialize a slot based on the supplied tupledesc
  */
@@ -713,17 +756,17 @@ BuildTupleFromCStrings(AttInMetadata *attinmeta, char **values)
  * Table Function capability. Currently used by EXPLAIN and SHOW ALL
  */
 TupOutputState *
-begin_tup_output_tupdesc(CommandDest dest, TupleDesc tupdesc)
+begin_tup_output_tupdesc(DestReceiver *dest, TupleDesc tupdesc)
 {
 	TupOutputState *tstate;
 
 	tstate = (TupOutputState *) palloc(sizeof(TupOutputState));
 
 	tstate->metadata = TupleDescGetAttInMetadata(tupdesc);
-	tstate->destfunc = DestToFunction(dest);
+	tstate->dest = dest;
 
-	(*tstate->destfunc->setup) (tstate->destfunc, (int) CMD_SELECT,
-								NULL, tupdesc, NIL);
+	(*tstate->dest->startup) (tstate->dest, (int) CMD_SELECT,
+							  NULL, tupdesc, NIL);
 
 	return tstate;
 }
@@ -741,9 +784,9 @@ do_tup_output(TupOutputState *tstate, char **values)
 	HeapTuple	tuple = BuildTupleFromCStrings(tstate->metadata, values);
 
 	/* send the tuple to the receiver */
-	(*tstate->destfunc->receiveTuple) (tuple,
-									   tstate->metadata->tupdesc,
-									   tstate->destfunc);
+	(*tstate->dest->receiveTuple) (tuple,
+								   tstate->metadata->tupdesc,
+								   tstate->dest);
 	/* clean up */
 	heap_freetuple(tuple);
 }
@@ -766,7 +809,7 @@ do_text_output_multiline(TupOutputState *tstate, char *text)
 		if (eol)
 			*eol++ = '\0';
 		else
-			eol = text +strlen(text);
+			eol = text + strlen(text);
 
 		do_tup_output(tstate, &text);
 		text = eol;
@@ -776,7 +819,8 @@ do_text_output_multiline(TupOutputState *tstate, char *text)
 void
 end_tup_output(TupOutputState *tstate)
 {
-	(*tstate->destfunc->cleanup) (tstate->destfunc);
+	(*tstate->dest->shutdown) (tstate->dest);
+	/* note that destroying the dest is not ours to do */
 	/* XXX worth cleaning up the attinmetadata? */
 	pfree(tstate);
 }