WITH CHECK OPTION support for auto-updatable VIEWs

For simple views which are automatically updatable, this patch allows
the user to specify what level of checking should be done on records
being inserted or updated.  For 'LOCAL CHECK', new tuples are validated
against the conditionals of the view they are being inserted into, while
for 'CASCADED CHECK' the new tuples are validated against the
conditionals for all views involved (from the top down).

This option is part of the SQL specification.

Dean Rasheed, reviewed by Pavel Stehule

1 files changed, 68 insertions, 0 deletions

diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index 6186a841556..832de439789 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -27,6 +27,7 @@
 #include "parser/parse_relation.h"
 #include "rewrite/rewriteDefine.h"
 #include "rewrite/rewriteManip.h"
+#include "rewrite/rewriteHandler.h"
 #include "rewrite/rewriteSupport.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
@@ -38,6 +39,24 @@
 static void checkViewTupleDesc(TupleDesc newdesc, TupleDesc olddesc);
 
 /*---------------------------------------------------------------------
+ * Validator for "check_option" reloption on views. The allowed values
+ * are "local" and "cascaded".
+ */
+void
+validateWithCheckOption(char *value)
+{
+	if (value == NULL ||
+		(pg_strcasecmp(value, "local") != 0 &&
+		 pg_strcasecmp(value, "cascaded") != 0))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("invalid value for \"check_option\" option"),
+			  errdetail("Valid values are \"local\", and \"cascaded\".")));
+	}
+}
+
+/*---------------------------------------------------------------------
  * DefineVirtualRelation
  *
  * Create the "view" relation. `DefineRelation' does all the work,
@@ -374,6 +393,9 @@ DefineView(ViewStmt *stmt, const char *queryString)
 	Query	   *viewParse;
 	Oid			viewOid;
 	RangeVar   *view;
+	ListCell   *cell;
+	bool		check_option;
+	bool		security_barrier;
 
 	/*
 	 * Run parse analysis to convert the raw parse tree to a Query.  Note this
@@ -411,6 +433,52 @@ DefineView(ViewStmt *stmt, const char *queryString)
 		errmsg("views must not contain data-modifying statements in WITH")));
 
 	/*
+	 * If the user specified the WITH CHECK OPTION, add it to the list of
+	 * reloptions.
+	 */
+	if (stmt->withCheckOption == LOCAL_CHECK_OPTION)
+		stmt->options = lappend(stmt->options,
+								makeDefElem("check_option",
+											(Node *) makeString("local")));
+	else if (stmt->withCheckOption == CASCADED_CHECK_OPTION)
+		stmt->options = lappend(stmt->options,
+								makeDefElem("check_option",
+											(Node *) makeString("cascaded")));
+
+	/*
+	 * Check that the view is auto-updatable if WITH CHECK OPTION was
+	 * specified.
+	 */
+	check_option = false;
+	security_barrier = false;
+
+	foreach(cell, stmt->options)
+	{
+		DefElem    *defel = (DefElem *) lfirst(cell);
+
+		if (pg_strcasecmp(defel->defname, "check_option") == 0)
+			check_option = true;
+		if (pg_strcasecmp(defel->defname, "security_barrier") == 0)
+			security_barrier = defGetBoolean(defel);
+	}
+
+	/*
+	 * If the check option is specified, look to see if the view is
+	 * actually auto-updatable or not.
+	 */
+	if (check_option)
+	{
+		const char *view_updatable_error =
+			view_query_is_auto_updatable(viewParse, security_barrier);
+
+		if (view_updatable_error)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("WITH CHECK OPTION is supported only on auto-updatable views"),
+					 errhint("%s", view_updatable_error)));
+	}
+
+	/*
 	 * If a list of column names was given, run through and insert these into
 	 * the actual query tree. - thomas 2000-03-08
 	 */