Tweak SPI_cursor_open to allow INSERT/UPDATE/DELETE RETURNING; this was

merely a matter of fixing the error check, since the underlying Portal
infrastructure already handles it.  This in turn allows these statements
to be used in some existing plpgsql and plperl contexts, such as a
plpgsql FOR loop.  Also, do some marginal code cleanup in places that
were being sloppy about distinguishing SELECT from SELECT INTO.

1 files changed, 25 insertions, 32 deletions

diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index c1f39f7c4f7..6c4cc585460 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.154 2006/08/12 02:52:04 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.155 2006/08/12 20:05:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -837,26 +837,12 @@ SPI_cursor_open(const char *name, void *plan,
 	planTree = (Plan *) linitial(ptlist);
 
 	/* Must be a query that returns tuples */
-	switch (queryTree->commandType)
-	{
-		case CMD_SELECT:
-			if (queryTree->into != NULL)
-				ereport(ERROR,
-						(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
-						 errmsg("cannot open SELECT INTO query as cursor")));
-			break;
-		case CMD_UTILITY:
-			if (!UtilityReturnsTuples(queryTree->utilityStmt))
-				ereport(ERROR,
-						(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
-						 errmsg("cannot open non-SELECT query as cursor")));
-			break;
-		default:
-			ereport(ERROR,
-					(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
-					 errmsg("cannot open non-SELECT query as cursor")));
-			break;
-	}
+	if (!QueryReturnsTuples(queryTree))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
+				 /* translator: %s is name of a SQL command, eg INSERT */
+				 errmsg("cannot open %s query as cursor",
+						CreateQueryTag(queryTree))));
 
 	/* Reset SPI result (note we deliberately don't touch lastoid) */
 	SPI_processed = 0;
@@ -876,7 +862,7 @@ SPI_cursor_open(const char *name, void *plan,
 		portal = CreatePortal(name, false, false);
 	}
 
-	/* Switch to portals memory and copy the parsetree and plan to there */
+	/* Switch to portal's memory and copy the parsetree and plan to there */
 	oldcontext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));
 	queryTree = copyObject(queryTree);
 	planTree = copyObject(planTree);
@@ -919,9 +905,9 @@ SPI_cursor_open(const char *name, void *plan,
 	 * Set up the portal.
 	 */
 	PortalDefineQuery(portal,
-					  NULL,
+					  NULL,		/* no statement name */
 					  spiplan->query,
-					  "SELECT", /* don't have the raw parse tree... */
+					  CreateQueryTag(queryTree),
 					  list_make1(queryTree),
 					  list_make1(planTree),
 					  PortalGetHeapMemory(portal));
@@ -954,9 +940,16 @@ SPI_cursor_open(const char *name, void *plan,
 	 */
 	PortalStart(portal, paramLI, snapshot);
 
-	Assert(portal->strategy == PORTAL_ONE_SELECT ||
-		   portal->strategy == PORTAL_ONE_RETURNING ||
-		   portal->strategy == PORTAL_UTIL_SELECT);
+	/*
+	 * If this test fails then we're out of sync with pquery.c about
+	 * which queries can return tuples...
+	 */
+	if (portal->strategy == PORTAL_MULTI_QUERY)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_CURSOR_DEFINITION),
+				 /* translator: %s is name of a SQL command, eg INSERT */
+				 errmsg("cannot open %s query as cursor",
+						CreateQueryTag(queryTree))));
 
 	/* Return the created portal */
 	return portal;
@@ -1046,12 +1039,12 @@ SPI_getargcount(void *plan)
 
 /*
  * Returns true if the plan contains exactly one command
- * and that command originates from normal SELECT (i.e.
- * *not* a SELECT ... INTO). In essence, the result indicates
- * if the command can be used with SPI_cursor_open
+ * and that command returns tuples to the caller (eg, SELECT or
+ * INSERT ... RETURNING, but not SELECT ... INTO). In essence,
+ * the result indicates if the command can be used with SPI_cursor_open
  *
  * Parameters
- *	  plan A plan previously prepared using SPI_prepare
+ *	  plan: A plan previously prepared using SPI_prepare
  */
 bool
 SPI_is_cursor_plan(void *plan)
@@ -1070,7 +1063,7 @@ SPI_is_cursor_plan(void *plan)
 	{
 		Query	   *queryTree = (Query *) linitial((List *) linitial(qtlist));
 
-		if (queryTree->commandType == CMD_SELECT && queryTree->into == NULL)
+		if (QueryReturnsTuples(queryTree))
 			return true;
 	}
 	return false;