Remove the prohibition on executing cursor commands through SPI_execute.

Vadim had included this restriction in the original design of the SPI code,
but I'm darned if I can see a reason for it.

I left the macro definition of SPI_ERROR_CURSOR in place, so as not to
needlessly break any SPI callers that are checking for it, but that code
will never actually be returned anymore.

doc/src/sgml/spi.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.54 2007/03/15 23:12:06 tgl Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/spi.sgml,v 1.55 2007/03/25 23:27:59 tgl Exp $ -->
 
 <chapter id="spi">
  <title>Server Programming Interface</title>
@@ -554,21 +554,11 @@ typedef struct
      </listitem>
     </varlistentry>
 
-    <varlistentry>
-     <term><symbol>SPI_ERROR_CURSOR</symbol></term>
-     <listitem>
-      <para>
-       if <command>DECLARE</>, <command>CLOSE</>, or <command>FETCH</>
-       was attempted
-      </para>
-     </listitem>
-    </varlistentry>
-
     <varlistentry>
      <term><symbol>SPI_ERROR_TRANSACTION</symbol></term>
      <listitem>
       <para>
-       if any command involving transaction manipulation was attempted
+       if a transaction manipulation command was attempted
        (<command>BEGIN</>,
        <command>COMMIT</>,
        <command>ROLLBACK</>,

src/backend/executor/spi.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.173 2007/03/17 03:15:38 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.174 2007/03/25 23:27:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1155,8 +1155,6 @@ SPI_result_code_string(int code)
 			return "SPI_ERROR_OPUNKNOWN";
 		case SPI_ERROR_UNCONNECTED:
 			return "SPI_ERROR_UNCONNECTED";
-		case SPI_ERROR_CURSOR:
-			return "SPI_ERROR_CURSOR";
 		case SPI_ERROR_ARGUMENT:
 			return "SPI_ERROR_ARGUMENT";
 		case SPI_ERROR_PARAM:
@@ -1490,13 +1488,6 @@ _SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
 							goto fail;
 						}
 					}
-					else if (IsA(stmt, DeclareCursorStmt) ||
-							 IsA(stmt, ClosePortalStmt) ||
-							 IsA(stmt, FetchStmt))
-					{
-						my_res = SPI_ERROR_CURSOR;
-						goto fail;
-					}
 					else if (IsA(stmt, TransactionStmt))
 					{
 						my_res = SPI_ERROR_TRANSACTION;

src/include/executor/spi.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/executor/spi.h,v 1.59 2007/03/15 23:12:06 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/executor/spi.h,v 1.60 2007/03/25 23:27:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -61,7 +61,7 @@ typedef struct _SPI_plan *SPIPlanPtr;
 #define SPI_ERROR_COPY			(-2)
 #define SPI_ERROR_OPUNKNOWN		(-3)
 #define SPI_ERROR_UNCONNECTED	(-4)
-#define SPI_ERROR_CURSOR		(-5)
+#define SPI_ERROR_CURSOR		(-5)			/* not used anymore */
 #define SPI_ERROR_ARGUMENT		(-6)
 #define SPI_ERROR_PARAM			(-7)
 #define SPI_ERROR_TRANSACTION	(-8)

src/pl/plpgsql/src/pl_exec.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.190 2007/03/15 23:12:07 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.191 2007/03/25 23:27:59 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2327,11 +2327,6 @@ exec_prepare_plan(PLpgSQL_execstate *estate,
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 						 errmsg("cannot COPY to/from client in PL/pgSQL")));
-			case SPI_ERROR_CURSOR:
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					errmsg("cannot manipulate cursors directly in PL/pgSQL"),
-						 errhint("Use PL/pgSQL's cursor features instead.")));
 			case SPI_ERROR_TRANSACTION:
 				ereport(ERROR,
 						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -2631,11 +2626,6 @@ exec_stmt_dynexecute(PLpgSQL_execstate *estate,
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("cannot COPY to/from client in PL/pgSQL")));
-		case SPI_ERROR_CURSOR:
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot manipulate cursors directly in PL/pgSQL"),
-					 errhint("Use PL/pgSQL's cursor features instead.")));
 		case SPI_ERROR_TRANSACTION:
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),