Add support for temporary views, including documentation and regression

tests. Contributed by Koju Iijima, review from Neil Conway, Gavin Sherry
and Tom Lane.

Also, fix error in description of WITH CHECK OPTION clause in the CREATE
VIEW reference page: it should be "CASCADED", not "CASCADE".

doc/src/sgml/ref/create_table.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.91 2005/01/22 23:22:17 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.92 2005/02/02 06:35:59 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -66,12 +66,12 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> is:
 
   <para>
    If a schema name is given (for example, <literal>CREATE TABLE
-   myschema.mytable ...</>) then the table is created in the
-   specified schema.  Otherwise it is created in the current schema.
-   Temporary tables exist in a special schema, so a schema name may not be
-   given when creating a temporary table.
-   The table name must be distinct from the name of any other table,
-   sequence, index, or view in the same schema.
+   myschema.mytable ...</>) then the table is created in the specified
+   schema.  Otherwise it is created in the current schema.  Temporary
+   tables exist in a special schema, so a schema name may not be given
+   when creating a temporary table.  The name of the table must be
+   distinct from the name of any other table, sequence, index, or view
+   in the same schema.
   </para>
 
   <para>

doc/src/sgml/ref/create_view.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_view.sgml,v 1.29 2005/01/04 00:39:53 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_view.sgml,v 1.30 2005/02/02 06:35:59 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -20,7 +20,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-CREATE [ OR REPLACE ] VIEW <replaceable class="PARAMETER">name</replaceable> [ ( <replaceable
+CREATE [ OR REPLACE ] [ TEMP | TEMPORARY ] VIEW <replaceable class="PARAMETER">name</replaceable> [ ( <replaceable
 class="PARAMETER">column_name</replaceable> [, ...] ) ] AS <replaceable class="PARAMETER">query</replaceable>
 </synopsis>
  </refsynopsisdiv>
@@ -43,10 +43,12 @@ class="PARAMETER">column_name</replaceable> [, ...] ) ] AS <replaceable class="P
 
   <para>
    If a schema name is given (for example, <literal>CREATE VIEW
-   myschema.myview ...</>) then the view is created in the
-   specified schema.  Otherwise it is created in the current schema.
-   The view name must be distinct from the name of any other view, table,
-   sequence, or index in the same schema.
+   myschema.myview ...</>) then the view is created in the specified
+   schema.  Otherwise it is created in the current schema.  Temporary
+   views exist in a special schema, so a schema name may not be given
+   when creating a temporary view. The name of the view must be
+   distinct from the name of any other view, table, sequence, or index
+   in the same schema.
   </para>
  </refsect1>
 
@@ -54,6 +56,28 @@ class="PARAMETER">column_name</replaceable> [, ...] ) ] AS <replaceable class="P
   <title>Parameters</title>
 
   <variablelist>
+   <varlistentry>
+    <term><literal>TEMPORARY</> or <literal>TEMP</></term>
+    <listitem>
+     <para>
+      If specified, the view is created as a temporary view.
+      Temporary views are automatically dropped at the end of the
+      current session. Temporary views are automatically placed in the
+      current backend's local temporary schema, so it is illegal to
+      specify a schema-qualified name for a temporary view. Existing
+      permanent relations with the same name are not visible to the
+      current session while the temporary view exists, unless they are
+      referenced with schema-qualified names.
+     </para>
+
+     <para>
+      If any of the base tables referenced by the view are temporary,
+      the view is created as a temporary view (whether
+      <literal>TEMPORARY</literal> is specified or not).
+     </para>
+    </listitem>
+   </varlistentry>
+   
    <varlistentry>
     <term><replaceable class="parameter">name</replaceable></term>
     <listitem>
@@ -102,7 +126,8 @@ class="PARAMETER">column_name</replaceable> [, ...] ) ] AS <replaceable class="P
    </para>
 
    <para>
-    Use the <command>DROP VIEW</command> statement to drop views.
+    Use the <xref linkend="sql-dropview" endterm="sql-dropview-title">
+    statement to drop views.
    </para>
 
    <para>
@@ -153,7 +178,7 @@ CREATE VIEW comedies AS
 <synopsis>
 CREATE VIEW <replaceable class="parameter">name</replaceable> [ ( <replaceable class="parameter">column</replaceable> [, ...] ) ]
     AS query
-    [ WITH [ CASCADE | LOCAL ] CHECK OPTION ]
+    [ WITH [ CASCADED | LOCAL ] CHECK OPTION ]
 </synopsis>
   </para>
 
@@ -184,12 +209,12 @@ CREATE VIEW <replaceable class="parameter">name</replaceable> [ ( <replaceable c
      </varlistentry>
 
      <varlistentry>
-      <term><literal>CASCADE</literal></term>
+      <term><literal>CASCADED</literal></term>
       <listitem>
        <para>
         Check for integrity on this view and on any dependent
-        view. <literal>CASCADE</> is assumed if neither
-        <literal>CASCADE</> nor <literal>LOCAL</> is specified.
+        view. <literal>CASCADED</> is assumed if neither
+        <literal>CASCADED</> nor <literal>LOCAL</> is specified.
        </para>
       </listitem>
      </varlistentry>

src/backend/commands/view.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.86 2004/12/31 21:59:42 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/view.c,v 1.87 2005/02/02 06:36:00 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,6 +21,7 @@
 #include "commands/view.h"
 #include "miscadmin.h"
 #include "nodes/makefuncs.h"
+#include "optimizer/clauses.h"
 #include "parser/parse_relation.h"
 #include "rewrite/rewriteDefine.h"
 #include "rewrite/rewriteManip.h"
@@ -30,7 +31,55 @@
 
 
 static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
+static bool isViewOnTempTable_walker(Node *node, void *context);
 
+/*---------------------------------------------------------------------
+ * isViewOnTempTable
+ *
+ * Returns true iff any of the relations underlying this view are
+ * temporary tables.
+ *---------------------------------------------------------------------
+ */
+static bool
+isViewOnTempTable(Query *viewParse)
+{
+	return isViewOnTempTable_walker((Node *) viewParse, NULL);
+}
+
+static bool
+isViewOnTempTable_walker(Node *node, void *context)
+{
+	if (node == NULL)
+		return false;
+
+	if (IsA(node, Query))
+	{
+		Query		*query = (Query *) node;
+		ListCell	*rtable;
+
+		foreach (rtable, query->rtable)
+		{
+			RangeTblEntry *rte = lfirst(rtable);
+			if (rte->rtekind == RTE_RELATION)
+			{
+				Relation rel = heap_open(rte->relid, AccessShareLock);
+				bool istemp = rel->rd_istemp;
+				heap_close(rel, AccessShareLock);
+				if (istemp)
+					return true;
+			}
+		}
+
+		return query_tree_walker(query,
+								 isViewOnTempTable_walker,
+								 context,
+								 QTW_IGNORE_JOINALIASES);
+	}
+
+	return expression_tree_walker(node,
+								  isViewOnTempTable_walker,
+								  context);
+}
 
 /*---------------------------------------------------------------------
  * DefineVirtualRelation
@@ -117,6 +166,13 @@ DefineVirtualRelation(const RangeVar *relation, List *tlist, bool replace)
 			aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS,
 						   RelationGetRelationName(rel));
 
+		/*
+		 * Due to the namespace visibility rules for temporary
+		 * objects, we should only end up replacing a temporary view
+		 * with another temporary view, and vice versa.
+		 */
+		Assert(relation->istemp == rel->rd_istemp);
+
 		/*
 		 * Create a tuple descriptor to compare against the existing view,
 		 * and verify it matches.
@@ -326,17 +382,29 @@ UpdateRangeTableOfViewParse(Oid viewOid, Query *viewParse)
  *-------------------------------------------------------------------
  */
 void
-DefineView(const RangeVar *view, Query *viewParse, bool replace)
+DefineView(RangeVar *view, Query *viewParse, bool replace)
 {
 	Oid			viewOid;
 
+	/*
+	 * If the user didn't explicitly ask for a temporary view, check
+	 * whether we need one implicitly.
+	 */
+	if (!view->istemp)
+	{
+		view->istemp = isViewOnTempTable(viewParse);
+		if (view->istemp)
+			ereport(NOTICE,
+					(errmsg("view \"%s\" will be a temporary view",
+							view->relname)));
+	}
+		
 	/*
 	 * Create the view relation
 	 *
 	 * NOTE: if it already exists and replace is false, the xact will be
 	 * aborted.
 	 */
-
 	viewOid = DefineVirtualRelation(view, viewParse->targetList, replace);
 
 	/*

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.482 2005/01/27 03:17:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.483 2005/02/02 06:36:01 neilc Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -4075,24 +4075,35 @@ transaction_mode_list_or_empty:
 
 /*****************************************************************************
  *
- *		QUERY:
- *				create view <viewname> '('target-list ')' AS <query>
+ *	QUERY:
+ *		CREATE [ OR REPLACE ] [ TEMP ] VIEW <viewname> '('target-list ')' AS <query>
  *
  *****************************************************************************/
 
-ViewStmt:	CREATE opt_or_replace VIEW qualified_name opt_column_list
+ViewStmt: CREATE OptTemp VIEW qualified_name opt_column_list
 				AS SelectStmt
 				{
 					ViewStmt *n = makeNode(ViewStmt);
-					n->replace = $2;
+					n->replace = false;
 					n->view = $4;
+					n->view->istemp = $2;
 					n->aliases = $5;
 					n->query = (Query *) $7;
-					$$ = (Node *)n;
+					$$ = (Node *) n;
+				}
+		| CREATE OR REPLACE OptTemp VIEW qualified_name opt_column_list
+				AS SelectStmt
+				{
+					ViewStmt *n = makeNode(ViewStmt);
+					n->replace = true;
+					n->view = $6;
+					n->view->istemp = $4;
+					n->aliases = $7;
+					n->query = (Query *) $9;
+					$$ = (Node *) n;
 				}
 		;
 
-
 /*****************************************************************************
  *
  *		QUERY:

src/include/commands/view.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/commands/view.h,v 1.21 2004/12/31 22:03:28 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/commands/view.h,v 1.22 2005/02/02 06:36:01 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,7 +16,7 @@
 
 #include "nodes/parsenodes.h"
 
-extern void DefineView(const RangeVar *view, Query *view_parse, bool replace);
+extern void DefineView(RangeVar *view, Query *view_parse, bool replace);
 extern void RemoveView(const RangeVar *view, DropBehavior behavior);
 
 #endif   /* VIEW_H */

src/test/regress/sql/create_view.sql

@@ -63,3 +63,131 @@ CREATE OR REPLACE VIEW viewtest AS
 
 DROP VIEW viewtest;
 DROP TABLE viewtest_tbl;
+
+-- tests for temporary views
+
+CREATE SCHEMA temp_view_test
+    CREATE TABLE base_table (a int, id int)
+    CREATE TABLE base_table2 (a int, id int);
+
+SET search_path TO temp_view_test, public;
+
+CREATE TEMPORARY TABLE temp_table (a int, id int);
+
+-- should be created in temp_view_test schema
+CREATE VIEW v1 AS SELECT * FROM base_table;
+-- should be created in temp object schema
+CREATE VIEW v1_temp AS SELECT * FROM temp_table;
+-- should be created in temp object schema
+CREATE TEMP VIEW v2_temp AS SELECT * FROM base_table;
+-- should be created in temp_views schema
+CREATE VIEW temp_view_test.v2 AS SELECT * FROM base_table;
+-- should fail
+CREATE VIEW temp_view_test.v3_temp AS SELECT * FROM temp_table;
+-- should fail
+CREATE SCHEMA test_schema
+    CREATE TEMP VIEW testview AS SELECT 1;
+
+-- joins: if any of the join relations are temporary, the view
+-- should also be temporary
+
+-- should be non-temp
+CREATE VIEW v3 AS
+    SELECT t1.a AS t1_a, t2.a AS t2_a
+    FROM base_table t1, base_table2 t2
+    WHERE t1.id = t2.id;
+-- should be temp (one join rel is temp)
+CREATE VIEW v4_temp AS
+    SELECT t1.a AS t1_a, t2.a AS t2_a
+    FROM base_table t1, temp_table t2
+    WHERE t1.id = t2.id;
+-- should be temp
+CREATE VIEW v5_temp AS
+    SELECT t1.a AS t1_a, t2.a AS t2_a, t3.a AS t3_a
+    FROM base_table t1, base_table2 t2, temp_table t3
+    WHERE t1.id = t2.id and t2.id = t3.id;
+
+-- subqueries
+CREATE VIEW v4 AS SELECT * FROM base_table WHERE id IN (SELECT id FROM base_table2);
+CREATE VIEW v5 AS SELECT t1.id, t2.a FROM base_table t1, (SELECT * FROM base_table2) t2;
+CREATE VIEW v6 AS SELECT * FROM base_table WHERE EXISTS (SELECT 1 FROM base_table2);
+CREATE VIEW v7 AS SELECT * FROM base_table WHERE NOT EXISTS (SELECT 1 FROM base_table2);
+CREATE VIEW v8 AS SELECT * FROM base_table WHERE EXISTS (SELECT 1);
+
+CREATE VIEW v6_temp AS SELECT * FROM base_table WHERE id IN (SELECT id FROM temp_table);
+CREATE VIEW v7_temp AS SELECT t1.id, t2.a FROM base_table t1, (SELECT * FROM temp_table) t2;
+CREATE VIEW v8_temp AS SELECT * FROM base_table WHERE EXISTS (SELECT 1 FROM temp_table);
+CREATE VIEW v9_temp AS SELECT * FROM base_table WHERE NOT EXISTS (SELECT 1 FROM temp_table);
+
+-- a view should also be temporary if it references a temporary view
+CREATE VIEW v10_temp AS SELECT * FROM v7_temp;
+CREATE VIEW v11_temp AS SELECT t1.id, t2.a FROM base_table t1, v10_temp t2;
+CREATE VIEW v12_temp AS SELECT true FROM v11_temp;
+
+-- a view should also be temporary if it references a temporary sequence
+CREATE SEQUENCE seq1;
+CREATE TEMPORARY SEQUENCE seq1_temp;
+CREATE VIEW v9 AS SELECT seq1.is_called;
+CREATE VIEW v13_temp AS SELECT seq1_temp.is_called;
+
+SELECT relname FROM pg_class
+    WHERE relname LIKE 'v_'  
+    AND relnamespace = (SELECT oid FROM pg_namespace WHERE nspname = 'temp_view_test')
+    ORDER BY relname;
+SELECT relname FROM pg_class
+    WHERE relname LIKE 'v%' 
+    AND relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname LIKE 'pg_temp%')
+    ORDER BY relname;
+
+CREATE SCHEMA testviewschm2;
+SET search_path TO testviewschm2, public;
+
+CREATE TABLE t1 (num int, name text);
+CREATE TABLE t2 (num2 int, value text);
+CREATE TEMP TABLE tt (num2 int, value text);
+
+CREATE VIEW nontemp1 AS SELECT * FROM t1 CROSS JOIN t2;
+CREATE VIEW temporal1 AS SELECT * FROM t1 CROSS JOIN tt;
+CREATE VIEW nontemp2 AS SELECT * FROM t1 INNER JOIN t2 ON t1.num = t2.num2;
+CREATE VIEW temporal2 AS SELECT * FROM t1 INNER JOIN tt ON t1.num = tt.num2;
+CREATE VIEW nontemp3 AS SELECT * FROM t1 LEFT JOIN t2 ON t1.num = t2.num2;
+CREATE VIEW temporal3 AS SELECT * FROM t1 LEFT JOIN tt ON t1.num = tt.num2;
+CREATE VIEW nontemp4 AS SELECT * FROM t1 LEFT JOIN t2 ON t1.num = t2.num2 AND t2.value = 'xxx';
+CREATE VIEW temporal4 AS SELECT * FROM t1 LEFT JOIN tt ON t1.num = tt.num2 AND tt.value = 'xxx';
+
+SELECT relname FROM pg_class
+    WHERE relname LIKE 'nontemp%'
+    AND relnamespace = (SELECT oid FROM pg_namespace WHERE nspname = 'testviewschm2')
+    ORDER BY relname;
+SELECT relname FROM pg_class
+    WHERE relname LIKE 'temporal%' 
+    AND relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname LIKE 'pg_temp%')
+    ORDER BY relname;
+
+CREATE TABLE tbl1 ( a int, b int);
+CREATE TABLE tbl2 (c int, d int);
+CREATE TABLE tbl3 (e int, f int);
+CREATE TABLE tbl4 (g int, h int);
+CREATE TEMP TABLE tmptbl (i int, j int);
+
+--Should be in testviewschm2
+CREATE   VIEW  pubview AS SELECT * FROM tbl1 WHERE tbl1.a
+BETWEEN (SELECT d FROM tbl2 WHERE c = 1) AND (SELECT e FROM tbl3 WHERE f = 2)
+AND EXISTS (SELECT g FROM tbl4 LEFT JOIN tbl3 ON tbl4.h = tbl3.f);
+
+SELECT count(*) FROM pg_class where relname = 'pubview'
+AND relnamespace IN (SELECT OID FROM pg_namespace WHERE nspname = 'testviewschm2');
+
+--Should be in temp object schema
+CREATE   VIEW  mytempview AS SELECT * FROM tbl1 WHERE tbl1.a
+BETWEEN (SELECT d FROM tbl2 WHERE c = 1) AND (SELECT e FROM tbl3 WHERE f = 2)
+AND EXISTS (SELECT g FROM tbl4 LEFT JOIN tbl3 ON tbl4.h = tbl3.f)
+AND NOT EXISTS (SELECT g FROM tbl4 LEFT JOIN tmptbl ON tbl4.h = tmptbl.j);
+
+SELECT count(*) FROM pg_class where relname LIKE 'mytempview'
+And relnamespace IN (SELECT OID FROM pg_namespace WHERE nspname LIKE 'pg_temp%');
+
+DROP SCHEMA temp_view_test CASCADE;
+DROP SCHEMA testviewschm2 CASCADE;
+
+SET search_path to public;