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".

Author: Neil Conway

doc/src/sgml/ref/create_table.sgml

@@ -1,5 +1,5 @@
 <!--
-$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

@@ -1,5 +1,5 @@
 <!--
-$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>
@@ -43,17 +43,41 @@ 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>
 
  <refsect1>
   <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 */