Implement "WITH / WITHOID OIDS" clause for CREATE TABLE AS. This is

intended to allow application authors to insulate themselves from
changes to the default value of 'default_with_oids' in future releases
of PostgreSQL.

This patch also fixes a bug in the earlier implementation of the
'default_with_oids' GUC variable: code in gram.y should not examine
the value of GUC variables directly due to synchronization issues.

doc/src/sgml/ref/create_table_as.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.19 2003/12/13 23:59:07 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.20 2004/01/10 23:28:44 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -20,7 +20,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable> [ (<replaceable>column_name</replaceable> [, ...] ) ]
+CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable> [ (<replaceable>column_name</replaceable> [, ...] ) ] [ [ WITH | WITHOUT ] OIDS ]
     AS <replaceable>query</replaceable>
 </synopsis>
  </refsynopsisdiv>
@@ -98,6 +98,20 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>WITH OIDS</literal></term>
+    <term><literal>WITHOUT OIDS</literal></term>
+     <listitem>
+      <para>
+       This optional clause specifies whether the table created by
+       <command>CREATE TABLE AS</command> should include OIDs. If
+       neither form of this clause if specified, the value of the
+       <varname>default_with_oids</varname> configuration parameter is
+       used.
+      </para>
+     </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><replaceable>query</replaceable></term>
     <listitem>
@@ -121,23 +135,30 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name
    This command is functionally similar to <xref
    linkend="sql-selectinto" endterm="sql-selectinto-title">, but it is
    preferred since it is less likely to be confused with other uses of
-   the <command>SELECT INTO</command> syntax.
+   the <command>SELECT INTO</> syntax. Furthermore, <command>CREATE
+   TABLE AS</command> offers a superset of the functionality offerred
+   by <command>SELECT INTO</command>.
   </para>
 
   <para>
-   Prior to <productname>PostgreSQL</> 7.5, <command>CREATE TABLE
-   AS</command> always included OIDs in the table it
+   Prior to <productname>PostgreSQL</productname> 7.5, <command>CREATE
+   TABLE AS</command> always included OIDs in the table it
    produced. Furthermore, these OIDs were newly generated: they were
    distinct from the OIDs of any of the rows in the source tables of
    the <command>SELECT</command> or <command>EXECUTE</command>
    statement. Therefore, if <command>CREATE TABLE AS</command> was
    frequently executed, the OID counter would be rapidly
-   incremented. As of <productname>PostgreSQL</> 7.5, the inclusion of
-   OIDs in the table generated by <command>CREATE TABLE AS</command>
-   is controlled by the <varname>default_with_oids</varname>
-   configuration variable. This variable currently defaults to true,
-   but will likely default to false in a future release of
-   <productname>PostgreSQL</>.
+   incremented. As of <productname>PostgresSQL</productname> 7.5,
+   the <command>CREATE TABLE AS</command> command allows the user to
+   explicitely specify whether OIDs should be included. If the
+   presence of OIDs is not explicitely specified,
+   the <varname>default_with_oids</varname> configuration variable is
+   used. While this variable currently defaults to true, the default
+   value may be changed in the future. Therefore, applications that
+   require OIDs in the table created by <command>CREATE TABLE
+   AS</command> should explicitely specify <literal>WITH
+   OIDS</literal> to ensure compatibility with future versions
+   of <productname>PostgreSQL</productname>.
   </para>
  </refsect1>
 

doc/src/sgml/runtime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.229 2004/01/06 17:26:22 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.230 2004/01/10 23:28:43 neilc Exp $
 -->
 
 <Chapter Id="runtime">
@@ -2437,17 +2437,17 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
       <term><varname>default_with_oids</varname> (<type>boolean</type>)</term>
       <listitem>
        <para>
-        This controls whether <command>CREATE TABLE</command> will
-        include OIDs in newly-created tables, if neither <literal>WITH
-        OIDS</literal> or <literal>WITHOUT OIDS</literal> have been
-        specified. It also determines whether OIDs will be included in
-        the table generated by <command>SELECT INTO</command> and
-        <command>CREATE TABLE AS</command>. In
+        This controls whether <command>CREATE TABLE</command>
+        and <command>CREATE TABLE AS</command> will include OIDs in
+        newly-created tables, if neither <literal>WITH OIDS</literal>
+        or <literal>WITHOUT OIDS</literal> have been specified. It
+        also determines whether OIDs will be included in the table
+        created by <command>SELECT INTO</command>. In
         <productname>PostgreSQL</productname> &version;
-        <varname>default_with_oids</varname> defaults to true. This is
-        also the behavior of previous versions of
-        <productname>PostgreSQL</productname>. However, assuming that
-        tables will contain OIDs by default is not
+        <varname>default_with_oids</varname> defaults to
+        true. This is also the behavior of previous versions
+        of <productname>PostgreSQL</productname>. However, assuming
+        that tables will contain OIDs by default is not
         encouraged. Therefore, this option will default to false in a
         future release of <productname>PostgreSQL</productname>.
        </para>

src/backend/commands/sequence.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.107 2004/01/07 18:56:25 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.108 2004/01/10 23:28:44 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -178,7 +178,7 @@ DefineSequence(CreateSeqStmt *seq)
 	stmt->relation = seq->sequence;
 	stmt->inhRelations = NIL;
 	stmt->constraints = NIL;
-	stmt->hasoids = false;
+	stmt->hasoids = MUST_NOT_HAVE_OIDS;
 	stmt->oncommit = ONCOMMIT_NOOP;
 
 	seqoid = DefineRelation(stmt, RELKIND_SEQUENCE);

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.94 2003/11/29 19:51:47 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.95 2004/01/10 23:28:44 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -47,6 +47,7 @@
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
+#include "utils/guc.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/relcache.h"
@@ -185,7 +186,25 @@ DefineRelation(CreateStmt *stmt, char relkind)
 	 */
 	descriptor = BuildDescForRelation(schema);
 
-	descriptor->tdhasoid = (stmt->hasoids || parentHasOids);
+	if (parentHasOids)
+		descriptor->tdhasoid = true;
+	else
+	{
+		switch (stmt->hasoids)
+		{
+			case MUST_HAVE_OIDS:
+				descriptor->tdhasoid = true;
+				break;
+
+			case MUST_NOT_HAVE_OIDS:
+				descriptor->tdhasoid = false;
+				break;
+
+			case DEFAULT_OIDS:
+				descriptor->tdhasoid = default_with_oids;
+				break;
+		}
+	}
 
 	if (old_constraints != NIL)
 	{

src/backend/commands/typecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.51 2003/11/29 19:51:47 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.52 2004/01/10 23:28:44 neilc Exp $
  *
  * DESCRIPTION
  *	  The "DefineFoo" routines take the parse tree and pick out the
@@ -1066,7 +1066,7 @@ DefineCompositeType(const RangeVar *typevar, List *coldeflist)
 	createStmt->tableElts = coldeflist;
 	createStmt->inhRelations = NIL;
 	createStmt->constraints = NIL;
-	createStmt->hasoids = false;
+	createStmt->hasoids = MUST_NOT_HAVE_OIDS;
 	createStmt->oncommit = ONCOMMIT_NOOP;
 
 	/*

src/backend/commands/view.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.79 2003/11/29 19:51:48 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.80 2004/01/10 23:28:44 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -141,7 +141,7 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
 		createStmt->tableElts = attrList;
 		createStmt->inhRelations = NIL;
 		createStmt->constraints = NIL;
-		createStmt->hasoids = false;
+		createStmt->hasoids = MUST_NOT_HAVE_OIDS;
 		createStmt->oncommit = ONCOMMIT_NOOP;
 
 		/*

src/backend/executor/execMain.c

@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.225 2004/01/07 18:56:26 neilc Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.226 2004/01/10 23:28:44 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -593,14 +593,7 @@ InitPlan(QueryDesc *queryDesc, bool explainOnly)
 	if (operation == CMD_SELECT && parseTree->into != NULL)
 	{
 		do_select_into = true;
-
-		/*
-		 * The presence of OIDs in the result set of SELECT INTO is
-		 * controlled by the default_with_oids GUC parameter. The
-		 * behavior in versions of PostgreSQL prior to 7.5 is to
-		 * always include OIDs.
-		 */
-		estate->es_force_oids = default_with_oids;
+		estate->es_force_oids = parseTree->intoHasOids;
 	}
 
 	/*

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.275 2004/01/06 23:55:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.276 2004/01/10 23:28:44 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1549,6 +1549,7 @@ _copyQuery(Query *from)
 	COPY_NODE_FIELD(utilityStmt);
 	COPY_SCALAR_FIELD(resultRelation);
 	COPY_NODE_FIELD(into);
+	COPY_SCALAR_FIELD(intoHasOids);
 	COPY_SCALAR_FIELD(hasAggs);
 	COPY_SCALAR_FIELD(hasSubLinks);
 	COPY_NODE_FIELD(rtable);
@@ -1623,6 +1624,7 @@ _copySelectStmt(SelectStmt *from)
 	COPY_NODE_FIELD(distinctClause);
 	COPY_NODE_FIELD(into);
 	COPY_NODE_FIELD(intoColNames);
+	COPY_SCALAR_FIELD(intoHasOids);
 	COPY_NODE_FIELD(targetList);
 	COPY_NODE_FIELD(fromClause);
 	COPY_NODE_FIELD(whereClause);

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.213 2004/01/06 23:55:18 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.214 2004/01/10 23:28:45 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -604,6 +604,7 @@ _equalQuery(Query *a, Query *b)
 	COMPARE_NODE_FIELD(utilityStmt);
 	COMPARE_SCALAR_FIELD(resultRelation);
 	COMPARE_NODE_FIELD(into);
+	COMPARE_SCALAR_FIELD(intoHasOids);
 	COMPARE_SCALAR_FIELD(hasAggs);
 	COMPARE_SCALAR_FIELD(hasSubLinks);
 	COMPARE_NODE_FIELD(rtable);
@@ -667,6 +668,7 @@ _equalSelectStmt(SelectStmt *a, SelectStmt *b)
 	COMPARE_NODE_FIELD(distinctClause);
 	COMPARE_NODE_FIELD(into);
 	COMPARE_NODE_FIELD(intoColNames);
+	COMPARE_SCALAR_FIELD(intoHasOids);
 	COMPARE_NODE_FIELD(targetList);
 	COMPARE_NODE_FIELD(fromClause);
 	COMPARE_NODE_FIELD(whereClause);

src/backend/parser/analyze.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.293 2004/01/05 20:58:58 neilc Exp $
+ *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.294 2004/01/10 23:28:45 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -41,6 +41,7 @@
 #include "utils/acl.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
+#include "utils/guc.h"
 #include "utils/lsyscache.h"
 #include "utils/relcache.h"
 #include "utils/syscache.h"
@@ -1974,6 +1975,21 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 	if (stmt->intoColNames)
 		applyColumnNames(qry->targetList, stmt->intoColNames);
 
+	switch (stmt->intoHasOids)
+	{
+		case MUST_HAVE_OIDS:
+			qry->intoHasOids = true;
+			break;
+
+		case MUST_NOT_HAVE_OIDS:
+			qry->intoHasOids = false;
+			break;
+
+		case DEFAULT_OIDS:
+			qry->intoHasOids = default_with_oids;
+			break;
+	}
+
 	/* mark column origins */
 	markTargetListOrigins(pstate, qry->targetList);
 

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.444 2004/01/10 02:21:08 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.445 2004/01/10 23:28:45 neilc Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -63,7 +63,6 @@
 #include "utils/numeric.h"
 #include "utils/datetime.h"
 #include "utils/date.h"
-#include "utils/guc.h"
 
 extern List *parsetree;			/* final parse result is delivered here */
 
@@ -109,6 +108,7 @@ static void doNegateFloat(Value *v);
 	JoinType			jtype;
 	DropBehavior		dbehavior;
 	OnCommitAction		oncommit;
+	ContainsOids		withoids;
 	List				*list;
 	FastList			fastlist;
 	Node				*node;
@@ -235,8 +235,9 @@ static void doNegateFloat(Value *v);
 %type <fun_param> func_arg
 %type <typnam>	func_return func_type aggr_argtype
 
-%type <boolean> arg_class TriggerForType OptTemp OptWithOids
-%type <oncommit>	OnCommitOption
+%type <boolean> arg_class TriggerForType OptTemp
+%type <oncommit> OnCommitOption
+%type <withoids> OptWithOids WithOidsAs
 
 %type <list>	for_update_clause opt_for_update_clause update_list
 %type <boolean>	opt_all
@@ -1824,14 +1825,9 @@ OptInherit: INHERITS '(' qualified_name_list ')'	{ $$ = $3; }
 		;
 
 OptWithOids:
-			WITH OIDS								{ $$ = TRUE; }
-			| WITHOUT OIDS							{ $$ = FALSE; }
-			/*
-			 * If the user didn't explicitely specify WITH or WITHOUT
-			 * OIDS, decide whether to include OIDs based on the
-			 * "default_with_oids" GUC var
-			 */
-			| /*EMPTY*/								{ $$ = default_with_oids; }
+			WITH OIDS								{ $$ = MUST_HAVE_OIDS; }
+			| WITHOUT OIDS							{ $$ = MUST_NOT_HAVE_OIDS; }
+			| /*EMPTY*/								{ $$ = DEFAULT_OIDS; }
 		;
 
 OnCommitOption:  ON COMMIT DROP				{ $$ = ONCOMMIT_DROP; }
@@ -1847,7 +1843,7 @@ OnCommitOption:  ON COMMIT DROP				{ $$ = ONCOMMIT_DROP; }
  */
 
 CreateAsStmt:
-			CREATE OptTemp TABLE qualified_name OptCreateAs AS SelectStmt
+			CREATE OptTemp TABLE qualified_name OptCreateAs WithOidsAs SelectStmt
 				{
 					/*
 					 * When the SelectStmt is a set-operation tree, we must
@@ -1864,10 +1860,23 @@ CreateAsStmt:
 					$4->istemp = $2;
 					n->into = $4;
 					n->intoColNames = $5;
+					n->intoHasOids = $6;
 					$$ = $7;
 				}
 		;
 
+/*
+ * To avoid a shift/reduce conflict in CreateAsStmt, we need to
+ * include the 'AS' terminal in the parsing of WITH/WITHOUT
+ * OIDS. Unfortunately that means this production is effectively a
+ * duplicate of OptWithOids.
+ */
+WithOidsAs:
+			WITH OIDS AS 							{ $$ = MUST_HAVE_OIDS; }
+			| WITHOUT OIDS AS 						{ $$ = MUST_NOT_HAVE_OIDS; }
+			| AS 									{ $$ = DEFAULT_OIDS; }
+			;
+
 OptCreateAs:
 			'(' CreateAsList ')'					{ $$ = $2; }
 			| /*EMPTY*/								{ $$ = NIL; }
@@ -4531,6 +4540,7 @@ simple_select:
 					n->targetList = $3;
 					n->into = $4;
 					n->intoColNames = NIL;
+					n->intoHasOids = DEFAULT_OIDS;
 					n->fromClause = $5;
 					n->whereClause = $6;
 					n->groupClause = $7;

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.251 2004/01/06 23:55:19 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.252 2004/01/10 23:28:45 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -55,6 +55,7 @@ typedef struct Query
 	int			resultRelation; /* target relation (index into rtable) */
 
 	RangeVar   *into;			/* target relation for SELECT INTO */
+	bool		intoHasOids;	/* should target relation contain OIDs? */
 
 	bool		hasAggs;		/* has aggregates in tlist or havingQual */
 	bool		hasSubLinks;	/* has subquery SubLink */
@@ -595,6 +596,16 @@ typedef enum SetOperation
 	SETOP_EXCEPT
 } SetOperation;
 
+typedef enum ContainsOids
+{
+	MUST_HAVE_OIDS,				/* WITH OIDS explicitely specified */
+	MUST_NOT_HAVE_OIDS,			/* WITHOUT OIDS explicitely specified */
+	DEFAULT_OIDS				/* neither specified; use the default,
+								 * which is the value of the
+								 * default_with_oids GUC var
+								 */
+} ContainsOids;
+
 typedef struct SelectStmt
 {
 	NodeTag		type;
@@ -602,13 +613,15 @@ typedef struct SelectStmt
 	/*
 	 * These fields are used only in "leaf" SelectStmts.
 	 *
-	 * into and intoColNames are a kluge; they belong somewhere else...
+	 * into, intoColNames and intoHasOids are a kluge; they belong
+	 * somewhere else...
 	 */
 	List	   *distinctClause; /* NULL, list of DISTINCT ON exprs, or
 								 * lcons(NIL,NIL) for all (SELECT
 								 * DISTINCT) */
 	RangeVar   *into;			/* target table (for select into table) */
 	List	   *intoColNames;	/* column names for into table */
+	ContainsOids intoHasOids;	/* should target table have OIDs? */
 	List	   *targetList;		/* the target list (of ResTarget) */
 	List	   *fromClause;		/* the FROM clause */
 	Node	   *whereClause;	/* WHERE qualification */
@@ -895,7 +908,7 @@ typedef struct CreateStmt
 	List	   *inhRelations;	/* relations to inherit from (list of
 								 * inhRelation) */
 	List	   *constraints;	/* constraints (list of Constraint nodes) */
-	bool		hasoids;		/* should it have OIDs? */
+	ContainsOids   hasoids;		/* should it have OIDs? */
 	OnCommitAction oncommit;	/* what do we do at COMMIT? */
 } CreateStmt;
 

src/test/regress/expected/without_oid.out

@@ -36,3 +36,27 @@ SELECT min(relpages) < max(relpages), min(reltuples) - max(reltuples)
 
 DROP TABLE wi;
 DROP TABLE wo;
+--
+-- WITH / WITHOUT OIDS in CREATE TABLE AS
+--
+CREATE TABLE create_table_test (
+    a int,
+    b int
+);
+COPY create_table_test FROM stdin;
+CREATE TABLE create_table_test2 WITH OIDS AS
+    SELECT a + b AS c1, a - b AS c2 FROM create_table_test;
+CREATE TABLE create_table_test3 WITHOUT OIDS AS
+    SELECT a + b AS c1, a - b AS c2 FROM create_table_test;
+SELECT count(oid) FROM create_table_test2;
+ count 
+-------
+     2
+(1 row)
+
+-- should fail
+SELECT count(oid) FROM create_table_test3;
+ERROR:  column "oid" does not exist
+DROP TABLE create_table_test;
+DROP TABLE create_table_test2;
+DROP TABLE create_table_test3;

src/test/regress/sql/without_oid.sql

@@ -33,3 +33,30 @@ SELECT min(relpages) < max(relpages), min(reltuples) - max(reltuples)
 
 DROP TABLE wi;
 DROP TABLE wo;
+
+--
+-- WITH / WITHOUT OIDS in CREATE TABLE AS
+--
+CREATE TABLE create_table_test (
+    a int,
+    b int
+);
+
+COPY create_table_test FROM stdin;
+5	10
+10	15
+\.
+
+CREATE TABLE create_table_test2 WITH OIDS AS
+    SELECT a + b AS c1, a - b AS c2 FROM create_table_test;
+
+CREATE TABLE create_table_test3 WITHOUT OIDS AS
+    SELECT a + b AS c1, a - b AS c2 FROM create_table_test;
+
+SELECT count(oid) FROM create_table_test2;
+-- should fail
+SELECT count(oid) FROM create_table_test3;
+
+DROP TABLE create_table_test;
+DROP TABLE create_table_test2;
+DROP TABLE create_table_test3;