auto-update-views.patch

diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
new file mode 100644
index 4bd942f..440d848
*** a/src/backend/catalog/information_schema.sql
--- b/src/backend/catalog/information_schema.sql
*************** CREATE VIEW views AS
*** 2497,2510 ****
             CAST('NONE' AS character_data) AS check_option,
  
             CAST(
!              CASE WHEN EXISTS (SELECT 1 FROM pg_rewrite WHERE ev_class = c.oid AND ev_type = '2' AND is_instead)
!                    AND EXISTS (SELECT 1 FROM pg_rewrite WHERE ev_class = c.oid AND ev_type = '4' AND is_instead)
!                   THEN 'YES' ELSE 'NO' END
               AS yes_or_no) AS is_updatable,
  
             CAST(
!              CASE WHEN EXISTS (SELECT 1 FROM pg_rewrite WHERE ev_class = c.oid AND ev_type = '3' AND is_instead)
!                   THEN 'YES' ELSE 'NO' END
               AS yes_or_no) AS is_insertable_into,
  
             CAST(
--- 2497,2507 ----
             CAST('NONE' AS character_data) AS check_option,
  
             CAST(
!              CASE WHEN pg_is_view_updatable(c.oid) THEN 'YES' ELSE 'NO' END
               AS yes_or_no) AS is_updatable,
  
             CAST(
!              CASE WHEN pg_is_view_insertable(c.oid) THEN 'YES' ELSE 'NO' END
               AS yes_or_no) AS is_insertable_into,
  
             CAST(
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
new file mode 100644
index f34f704..f4cb6dc
*** a/src/backend/nodes/copyfuncs.c
--- b/src/backend/nodes/copyfuncs.c
*************** _copyRangeTblEntry(const RangeTblEntry *
*** 1994,1999 ****
--- 1994,2000 ----
  	COPY_SCALAR_FIELD(checkAsUser);
  	COPY_BITMAPSET_FIELD(selectedCols);
  	COPY_BITMAPSET_FIELD(modifiedCols);
+ 	COPY_NODE_FIELD(securityQuals);
  
  	return newnode;
  }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
new file mode 100644
index b4b1c22..51c73b5
*** a/src/backend/nodes/equalfuncs.c
--- b/src/backend/nodes/equalfuncs.c
*************** _equalRangeTblEntry(const RangeTblEntry
*** 2305,2310 ****
--- 2305,2311 ----
  	COMPARE_SCALAR_FIELD(checkAsUser);
  	COMPARE_BITMAPSET_FIELD(selectedCols);
  	COMPARE_BITMAPSET_FIELD(modifiedCols);
+ 	COMPARE_NODE_FIELD(securityQuals);
  
  	return true;
  }
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
new file mode 100644
index b130902..4d461b2
*** a/src/backend/nodes/nodeFuncs.c
--- b/src/backend/nodes/nodeFuncs.c
*************** range_table_walker(List *rtable,
*** 1942,1947 ****
--- 1942,1950 ----
  					return true;
  				break;
  		}
+ 
+ 		if (walker(rte->securityQuals, context))
+ 			return true;
  	}
  	return false;
  }
*************** range_table_mutator(List *rtable,
*** 2653,2658 ****
--- 2656,2662 ----
  				MUTATE(newrte->values_lists, rte->values_lists, List *);
  				break;
  		}
+ 		MUTATE(newrte->securityQuals, rte->securityQuals, List *);
  		newrt = lappend(newrt, newrte);
  	}
  	return newrt;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
new file mode 100644
index 01f381e..eed6869
*** a/src/backend/nodes/outfuncs.c
--- b/src/backend/nodes/outfuncs.c
*************** _outRangeTblEntry(StringInfo str, const
*** 2382,2387 ****
--- 2382,2388 ----
  	WRITE_OID_FIELD(checkAsUser);
  	WRITE_BITMAPSET_FIELD(selectedCols);
  	WRITE_BITMAPSET_FIELD(modifiedCols);
+ 	WRITE_NODE_FIELD(securityQuals);
  }
  
  static void
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
new file mode 100644
index 1eb7582..bb4009c
*** a/src/backend/nodes/readfuncs.c
--- b/src/backend/nodes/readfuncs.c
*************** _readRangeTblEntry(void)
*** 1229,1234 ****
--- 1229,1235 ----
  	READ_OID_FIELD(checkAsUser);
  	READ_BITMAPSET_FIELD(selectedCols);
  	READ_BITMAPSET_FIELD(modifiedCols);
+ 	READ_NODE_FIELD(securityQuals);
  
  	READ_DONE();
  }
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
new file mode 100644
index ccd69fc..3cb0a65
*** a/src/backend/optimizer/plan/setrefs.c
--- b/src/backend/optimizer/plan/setrefs.c
*************** set_plan_references(PlannerInfo *root, P
*** 224,229 ****
--- 224,230 ----
  		newrte->ctecoltypes = NIL;
  		newrte->ctecoltypmods = NIL;
  		newrte->ctecolcollations = NIL;
+ 		newrte->securityQuals = NIL;
  
  		glob->finalrtable = lappend(glob->finalrtable, newrte);
  
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
new file mode 100644
index 8f75948..2f9a118
*** a/src/backend/rewrite/rewriteHandler.c
--- b/src/backend/rewrite/rewriteHandler.c
***************
*** 14,19 ****
--- 14,20 ----
  #include "postgres.h"
  
  #include "access/sysattr.h"
+ #include "catalog/heap.h"
  #include "catalog/pg_type.h"
  #include "commands/trigger.h"
  #include "nodes/makefuncs.h"
*************** static List *matchLocks(CmdType event, R
*** 60,65 ****
--- 61,67 ----
  		   int varno, Query *parsetree);
  static Query *fireRIRrules(Query *parsetree, List *activeRIRs,
  			 bool forUpdatePushedDown);
+ static Query *rewriteSecurityQuals(Query *parsetree);
  
  
  /*
*************** fireRules(Query *parsetree,
*** 1829,1834 ****
--- 1831,2650 ----
  
  
  /*
+  * get_view_query - get the query from a view's _RETURN rule.
+  */
+ static Query *
+ get_view_query(Relation view)
+ {
+ 	int		i;
+ 
+ 	Assert(view->rd_rel->relkind == RELKIND_VIEW);
+ 
+ 	for (i = 0; i < view->rd_rules->numLocks; i++)
+ 	{
+ 		RewriteRule *rule = view->rd_rules->rules[i];
+ 
+ 		if (rule->event == CMD_SELECT)
+ 		{
+ 			/* A _RETURN rule should have only one action */
+ 			if (list_length(rule->actions) != 1)
+ 				elog(ERROR, "invalid _RETURN rule action specification");
+ 
+ 			return linitial(rule->actions);
+ 		}
+ 	}
+ 
+ 	elog(ERROR, "failed to find _RETURN rule for view");
+ 	return NULL;	/* keep compiler quiet */
+ }
+ 
+ 
+ /*
+  * test_auto_update_view -
+  *	  Test if the specified view can be automatically updated. This will
+  *	  either return NULL (if the view can be updated) or the reason that it
+  *	  cannot.
+  *
+  * Note that the checks performed here are local to this view.  It does not
+  * check that the view's underlying base relation is updatable.
+  */
+ static const char *
+ test_auto_update_view(Relation view)
+ {
+ 	Query	   *viewquery;
+ 	RangeTblRef *rtr;
+ 	RangeTblEntry *base_rte;
+ 	Bitmapset  *bms;
+ 	ListCell   *cell;
+ 
+ 	/*
+ 	 * Check if the view is simply updatable.  According to SQL-92 this means:
+ 	 *	- No DISTINCT clauses.
+ 	 *	- Every TLE is a column reference, and appears at most once.
+ 	 *	- Refers to a single base relation.
+ 	 *	- No GROUP BY or HAVING clauses.
+ 	 *	- No set operations (UNION, INTERSECT or EXCEPT).
+ 	 *	- No sub-queries in the WHERE clause.
+ 	 *
+ 	 * We relax this last restriction since it would actually be more work to
+ 	 * enforce it than to simply allow it.  In addition (for now) we impose
+ 	 * the following additional constraints, based on features that are not
+ 	 * part of SQL-92:
+ 	 *	- No DISTINCT ON clauses.
+ 	 *	- No window functions.
+ 	 *	- No CTEs (WITH or WITH RECURSIVE).
+ 	 *	- No OFFSET or LIMIT clauses.
+ 	 *	- No system columns.
+ 	 *
+ 	 * Note that we do these checks without recursively expanding the view.
+ 	 * The base relation may be a view, and it might have INSTEAD OF triggers
+ 	 * or rules, in which case it need not satisfy these constraints.
+ 	 */
+ 	viewquery = get_view_query(view);
+ 
+ 	if (viewquery->distinctClause != NIL ||
+ 		viewquery->hasDistinctOn)
+ 		return "Views containing DISTINCT are not updatable";
+ 
+ 	if (viewquery->groupClause != NIL)
+ 		return "Views containing GROUP BY are not updatable";
+ 
+ 	if (viewquery->havingQual != NULL)
+ 		return "Views containing HAVING are not updatable";
+ 
+ 	if (viewquery->hasAggs)
+ 		return "Views containing aggregates are not updatable";
+ 
+ 	if (viewquery->hasWindowFuncs)
+ 		return "Views containing window functions are not updatable";
+ 
+ 	if (viewquery->setOperations != NULL)
+ 		return "Views containing UNION, INTERSECT or EXCEPT are not updatable";
+ 
+ 	if (viewquery->hasRecursive ||
+ 		viewquery->cteList != NIL)
+ 		return "Views containing WITH [RECURSIVE] are not updatable";
+ 
+ 	if (viewquery->limitOffset != NULL ||
+ 		viewquery->limitCount != NULL)
+ 		return "Views containing OFFSET or LIMIT are not updatable";
+ 
+ 	/*
+ 	 * The view query should select from a single base relation, which must be
+ 	 * a table or another view.
+ 	 */
+ 	if (list_length(viewquery->jointree->fromlist) == 0)
+ 		return "Views with no base relations are not updatable";
+ 
+ 	if (list_length(viewquery->jointree->fromlist) > 1)
+ 		return "Views with multiple base relations are not updatable";
+ 
+ 	rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
+ 	if (!IsA(rtr, RangeTblRef))
+ 		return "Views that are not based on tables or views are not updatable";
+ 
+ 	base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
+ 	if (base_rte->rtekind != RTE_RELATION)
+ 		return "Views that are not based on tables or views are not updatable";
+ 
+ 	/*
+ 	 * The view's targetlist entries should all be Vars referring to columns
+ 	 * in the base relation, and no 2 should refer to the same base column.
+ 	 *
+ 	 * Note that we don't bother freeing resources allocated here if we
+ 	 * return early, since that is an error condition.
+ 	 */
+ 	bms = NULL;
+ 	foreach(cell, viewquery->targetList)
+ 	{
+ 		TargetEntry *tle = (TargetEntry *) lfirst(cell);
+ 		Var		   *var = (Var *) tle->expr;
+ 
+ 		if (!IsA(var, Var))
+ 			return "Views with columns that are not simple references to columns in the base relation are not updatable";
+ 
+ 		if (var->varattno < 0)
+ 			return "Views that refer to system columns are not updatable";
+ 
+ 		if (var->varattno == 0)
+ 			return "Views that refer to whole rows from the base relation are not updatable";
+ 
+ 		if (bms_is_member(var->varattno, bms))
+ 			return "Views that refer to the same column more than once are not updatable";
+ 
+ 		bms = bms_add_member(bms, var->varattno);
+ 	}
+ 
+ 	bms_free(bms);
+ 	return NULL;	/* the view is simply updatable */
+ }
+ 
+ 
+ /*
+  * rewriteTargetView -
+  *	  attempt to rewrite a query where the target relation is a view, so that
+  *	  the view's base relation becomes the target relation.
+  *
+  * This only handles the case where there are no INSTEAD OF triggers to update
+  * the view.  If there are INSTEAD OF triggers, this function will return NULL
+  * and the view modification is handled later by fireRIRrules.
+  *
+  * Note that the base relation here may itself be a view, which may or may not
+  * have INSTEAD OF triggers or rules to handle the update.  That is handled by
+  * the recursion in RewriteQuery.
+  */
+ static Query *
+ rewriteTargetView(Query *parsetree, Relation view)
+ {
+ 	TriggerDesc *trigDesc = view->trigdesc;
+ 	const char *auto_update_detail;
+ 	Query	   *viewquery;
+ 	RangeTblRef *rtr;
+ 	int			base_rt_index;
+ 	RangeTblEntry *base_rte;
+ 	List	   *view_targetlist;
+ 	bool		same_cols;
+ 	ListCell   *cell;
+ 	int			rt_index;
+ 	List	   *new_rtable;
+ 	RangeTblEntry *view_rte;
+ 
+ 	/* The view must have INSTEAD OF triggers or be simply updatable */
+ 	switch (parsetree->commandType)
+ 	{
+ 		case CMD_INSERT:
+ 			if (trigDesc && trigDesc->trig_insert_instead_row)
+ 				return NULL;	/* INSTEAD OF INSERT trigger will be used */
+ 
+ 			auto_update_detail = test_auto_update_view(view);
+ 			if (auto_update_detail)
+ 				ereport(ERROR,
+ 						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ 						 errmsg("cannot insert into view \"%s\"",
+ 								RelationGetRelationName(view)),
+ 						 errdetail("%s.", auto_update_detail),
+ 						 errhint("You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.")));
+ 			break;
+ 		case CMD_UPDATE:
+ 			if (trigDesc && trigDesc->trig_update_instead_row)
+ 				return NULL;	/* INSTEAD OF UPDATE trigger will be used */
+ 
+ 			auto_update_detail = test_auto_update_view(view);
+ 			if (auto_update_detail)
+ 				ereport(ERROR,
+ 						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ 						 errmsg("cannot update view \"%s\"",
+ 								RelationGetRelationName(view)),
+ 						 errdetail("%s.", auto_update_detail),
+ 						 errhint("You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.")));
+ 			break;
+ 		case CMD_DELETE:
+ 			if (trigDesc && trigDesc->trig_delete_instead_row)
+ 				return NULL;	/* INSTEAD OF DELETE trigger will be used */
+ 
+ 			auto_update_detail = test_auto_update_view(view);
+ 			if (auto_update_detail)
+ 				ereport(ERROR,
+ 						(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ 						 errmsg("cannot delete from view \"%s\"",
+ 								RelationGetRelationName(view)),
+ 						 errdetail("%s.", auto_update_detail),
+ 						 errhint("You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.")));
+ 			break;
+ 		default:
+ 			elog(ERROR, "unrecognized CmdType: %d", (int) parsetree->commandType);
+ 			break;
+ 	}
+ 
+ 	/*
+ 	 * The view is simply updatable, which means that it should have a single
+ 	 * base relation.
+ 	 */
+ 	viewquery = get_view_query(view);
+ 	Assert(list_length(viewquery->jointree->fromlist) == 1);
+ 
+ 	rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
+ 	Assert(IsA(rtr, RangeTblRef));
+ 
+ 	base_rt_index = rtr->rtindex;
+ 	base_rte = rt_fetch(base_rt_index, viewquery->rtable);
+ 	Assert(base_rte->rtekind == RTE_RELATION);
+ 
+ 	/*
+ 	 * Make a copy of the view's targetlist, adjusting its Vars to allow it
+ 	 * to be plugged into the main query.
+ 	 */
+ 	view_targetlist = copyObject(viewquery->targetList);
+ 
+ 	ChangeVarNodes((Node *) view_targetlist,
+ 				   base_rt_index, parsetree->resultRelation, 0);
+ 
+ 	/**
+ 	 * Test for the simple case where the view has all the same columns as the
+ 	 * base relation, in the same order.
+ 	 */
+ 	same_cols = true;
+ 	foreach(cell, view_targetlist)
+ 	{
+ 		TargetEntry *tle = (TargetEntry *) lfirst(cell);
+ 		Var		   *var = (Var *) tle->expr;
+ 
+ 		if (var->varattno != tle->resno)
+ 		{
+ 			/* view columns are in a different order */
+ 			same_cols = false;
+ 			break;
+ 		}
+ 	}
+ 
+ 	/*
+ 	 * Replace the old view target RTE with a new RTE referring to the base
+ 	 * relation.  Since we are not changing the result relation index, there
+ 	 * is no need to update any varnos in the original query.
+ 	 *
+ 	 * Note that we need to keep the original view RTE, even though it will
+ 	 * not be used directly in the query, so that the correct permissions
+ 	 * checks are still done against it.  This is appended to the end of the
+ 	 * rangetable.
+ 	 */
+ 	rt_index = 1;
+ 	new_rtable = NIL;
+ 	foreach(cell, parsetree->rtable)
+ 	{
+ 		RangeTblEntry *rte = (RangeTblEntry *) lfirst(cell);
+ 
+ 		if (rt_index == parsetree->resultRelation)
+ 		{
+ 			/*
+ 			 * Create the new target RTE using the base relation.  Copy any
+ 			 * permissions checks from the original view target RTE, adjusting
+ 			 * the column numbers if necessary, and performing the checks as
+ 			 * the view's owner.
+ 			 */
+ 			RangeTblEntry *newrte = (RangeTblEntry *) copyObject(base_rte);
+ 			newrte->requiredPerms = rte->requiredPerms;
+ 			newrte->checkAsUser = view->rd_rel->relowner;
+ 			newrte->selectedCols = bms_copy(rte->selectedCols);
+ 			newrte->modifiedCols = bms_copy(rte->modifiedCols);
+ 
+ 			if (!same_cols)
+ 			{
+ 				newrte->selectedCols = adjust_column_set(newrte->selectedCols,
+ 														 view_targetlist);
+ 				newrte->modifiedCols = adjust_column_set(newrte->modifiedCols,
+ 														 view_targetlist);
+ 			}
+ 
+ 			/*
+ 			 * Move any security barrier quals from the view RTE onto the new
+ 			 * base relation RTE, since the original view RTE will not be
+ 			 * referenced in the final query.
+ 			 */
+ 			newrte->securityQuals = rte->securityQuals;
+ 			rte->securityQuals = NIL;
+ 
+ 			/*
+ 			 * Keep the original view RTE so that executor also checks that
+ 			 * the current user has the required permissions on the view
+ 			 */
+ 			view_rte = rte;
+ 			rte = newrte;
+ 		}
+ 		new_rtable = lappend(new_rtable, rte);
+ 		rt_index++;
+ 	}
+ 	parsetree->rtable = lappend(new_rtable, view_rte);
+ 
+ 	/*
+ 	 * For UPDATE/DELETE, rewriteTargetListUD will have added a wholerow junk
+ 	 * TLE for the view to the end of the targetlist which we no longer need.
+ 	 * We remove this now to avoid unnecessary work when we process the
+ 	 * targetlist.  Note that when we recurse through rewriteQuery a new junk
+ 	 * TLE will be added to allow the executor to find the row in the base
+ 	 * relation.
+ 	 */
+ 	if (parsetree->commandType != CMD_INSERT)
+ 	{
+ 		TargetEntry *tle = (TargetEntry *)
+ 			lfirst(list_tail(parsetree->targetList));
+ 
+ 		Assert(IsA(tle->expr, Var) && ((Var *) tle->expr)->varattno == 0);
+ 		parsetree->targetList = list_delete_ptr(parsetree->targetList, tle);
+ 	}
+ 
+ 	/*
+ 	 * If the view's columns don't match the base relation's columns, we need
+ 	 * to update the targetlist to point to the columns in the base relation,
+ 	 * and similarly update any Vars in the query that refer to the result
+ 	 * relation.
+ 	 *
+ 	 * Note that this destroys the resno ordering of the targetlist, but that
+ 	 * will be restored when we recurse through rewriteQuery which will invoke
+ 	 * rewriteTargetListIU on this updated targetlist.
+ 	 */
+ 	if (!same_cols)
+ 	{
+ 		/* Update the main query's targetlist */
+ 		foreach(cell, parsetree->targetList)
+ 		{
+ 			TargetEntry *tle = (TargetEntry *) lfirst(cell);
+ 			TargetEntry *view_tle;
+ 
+ 			/* Ignore system columns */
+ 			if (tle->resjunk || tle->resno <= 0)
+ 				continue;
+ 
+ 			view_tle = get_tle_by_resno(view_targetlist, tle->resno);
+ 			if (view_tle == NULL)
+ 				elog(ERROR, "View column %d not found", tle->resno);
+ 
+ 			tle->resno = ((Var *) view_tle->expr)->varattno;
+ 		}
+ 
+ 		/* Update any Vars referring to the result relation. */
+ 		parsetree =
+ 			(Query *) ResolveNew((Node *) parsetree,
+ 								 parsetree->resultRelation,
+ 								 0,
+ 								 view_rte,
+ 								 view_targetlist,
+ 								 parsetree->commandType,
+ 								 parsetree->resultRelation,
+ 								 &parsetree->hasSubLinks);
+ 	}
+ 
+ 	/*
+ 	 * For UPDATE/DELETE, deal with any quals from the view's jointree.  We
+ 	 * know that there is just one relation in the view, so any references to
+ 	 * that relation in the view's quals need to be updated to refer to the
+ 	 * corresponding relation in the main query (the result relation).
+ 	 *
+ 	 * If the view is not a security barrier then we simply add the view quals
+ 	 * to the main query.  However, if the view is a security barrier then its
+ 	 * quals must take precedence over any of the user's quals.  Here we just
+ 	 * make a note of such quals on the relevant RTE so that we can deal with
+ 	 * them later in rewriteSecurityQuals, which will turn the RTE into a
+ 	 * subquery.
+ 	 *
+ 	 * For INSERT the view's quals are not needed for now.  When we implement
+ 	 * WITH CHECK OPTION, this might be a good time to collect them.
+ 	 */
+ 	if (parsetree->commandType != CMD_INSERT &&
+ 		viewquery->jointree->quals != NULL)
+ 	{
+ 		Node	   *viewqual = copyObject(viewquery->jointree->quals);
+ 
+ 		ChangeVarNodes(viewqual, base_rt_index, parsetree->resultRelation, 0);
+ 
+ 		if (RelationIsSecurityView(view))
+ 		{
+ 			base_rte = rt_fetch(parsetree->resultRelation, parsetree->rtable);
+ 			base_rte->securityQuals = lcons(viewqual,
+ 											base_rte->securityQuals);
+ 		}
+ 		else
+ 			AddQual(parsetree, (Node *) viewqual);
+ 	}
+ 
+ 	return parsetree;
+ }
+ 
+ 
+ /*
+  * rewriteSecurityQual -
+  *	  rewrite the specified security barrier qual on a query RTE, turning the
+  *	  RTE into a subquery.
+  */
+ static Query *
+ rewriteSecurityQual(Query *parsetree, int rt_index,
+ 					bool is_result_relation, Node *qual)
+ {
+ 	RangeTblEntry  *rte;
+ 	List		   *targetlist = NIL;
+ 	List		   *inverse_targetlist = NIL;
+ 	List		   *colnames = NIL;
+ 	Relation		relation;
+ 	AttrNumber		attno;
+ 	Var			   *var;
+ 	TargetEntry	   *tle;
+ 	Query		   *subquery;
+ 	RangeTblEntry  *subrte;
+ 	RangeTblRef	   *subrtr;
+ 	ListCell	   *cell;
+ 
+ 	rte = rt_fetch(rt_index, parsetree->rtable);
+ 
+ 	/*
+ 	 * There are 2 possible cases:
+ 	 *
+ 	 * 1). A relation RTE, which we turn into a subquery RTE containing all
+ 	 * referenced columns.
+ 	 *
+ 	 * 2). A subquery RTE (either from a prior call to this function or from
+ 	 * an expanded view).  In this case we build a new subquery on top of it
+ 	 * to isolate this security barrier qual from any other quals.
+ 	 */
+ 	switch (rte->rtekind)
+ 	{
+ 		case RTE_RELATION:
+ 			/*
+ 			 * Build the subquery targetlist from the columns used from the
+ 			 * underlying table and an inverse targetlist to map varattnos in
+ 			 * the main query onto the new subquery columns.
+ 			 */
+ 			relation = heap_open(rte->relid, NoLock);
+ 
+ 			for (attno = FirstLowInvalidHeapAttributeNumber;
+ 				 attno <= relation->rd_att->natts; attno++)
+ 			{
+ 				Form_pg_attribute att_tup;
+ 				char	   *attname;
+ 
+ 				/* Ignore columns that aren't used */
+ 				if (!attribute_used((Node *) parsetree, rt_index, attno, 0))
+ 					continue;
+ 
+ 				if (attno == InvalidAttrNumber)
+ 				{
+ 					/* whole-row attribute */
+ 					var = makeWholeRowVar(rte, 1, 0, false);
+ 					attname = "wholerow";
+ 				}
+ 				else
+ 				{
+ 					/* regular table column or system attribute */
+ 					if (attno >= 1)
+ 						att_tup = relation->rd_att->attrs[attno - 1];
+ 					else
+ 						att_tup = SystemAttributeDefinition(attno,
+ 												relation->rd_rel->relhasoids);
+ 
+ 					var =  makeVar(1,
+ 								   attno,
+ 								   att_tup->atttypid,
+ 								   att_tup->atttypmod,
+ 								   att_tup->attcollation,
+ 								   0);
+ 					attname = NameStr(att_tup->attname);
+ 				}
+ 
+ 				/* target entry for new subquery targetlist */
+ 				tle = makeTargetEntry((Expr *) var,
+ 									  list_length(targetlist) + 1,
+ 									  pstrdup(attname),
+ 									  false);
+ 				targetlist = lappend(targetlist, tle);
+ 
+ 				/* inverse target entry for rewriting the main query */
+ 				var = copyObject(var);
+ 				var->varattno = list_length(targetlist);
+ 				tle = makeTargetEntry((Expr *) var,
+ 									  attno,
+ 									  pstrdup(attname),
+ 									  false);
+ 				inverse_targetlist = lappend(inverse_targetlist, tle);
+ 
+ 				colnames = lappend(colnames, makeString(pstrdup(attname)));
+ 			}
+ 			heap_close(relation, NoLock);
+ 
+ 			/*
+ 			 * Turn the main relation RTE into a security barrier subquery
+ 			 * RTE, moving all permissions checks and rowMarks down into the
+ 			 * subquery.
+ 			 */
+ 			subquery = makeNode(Query);
+ 			subquery->commandType = CMD_SELECT;
+ 			subquery->querySource = QSRC_INSTEAD_RULE;
+ 			subquery->targetList = targetlist;
+ 
+ 			subrte = copyObject(rte);
+ 			subrte->inFromCl = true;
+ 			subrte->securityQuals = NIL;
+ 			subquery->rtable = list_make1(subrte);
+ 
+ 			subrtr = makeNode(RangeTblRef);
+ 			subrtr->rtindex = 1;
+ 			subquery->jointree = makeFromExpr(list_make1(subrtr), qual);
+ 			subquery->hasSubLinks = checkExprHasSubLink(qual);
+ 
+ 			foreach(cell, parsetree->rowMarks)
+ 			{
+ 				RowMarkClause *rc = (RowMarkClause *) lfirst(cell);
+ 				if (rc->rti == rt_index)
+ 				{
+ 					parsetree->rowMarks = list_delete(parsetree->rowMarks,
+ 													  rc);
+ 					rc->rti = 1;
+ 					subquery->rowMarks = list_make1(rc);
+ 					subquery->hasForUpdate = rc->forUpdate;
+ 					break;
+ 				}
+ 			}
+ 
+ 			/*
+ 			 * If this RTE was the result relation, then we need to lock the
+ 			 * rows coming from it.  Note that by the time we get here, this
+ 			 * RTE will no longer be the result relation, so we have to rely
+ 			 * on the flag passed in.
+ 			 */
+ 			if (is_result_relation)
+ 				applyLockingClause(subquery, 1, true, false, true);
+ 
+ 			rte->rtekind = RTE_SUBQUERY;
+ 			rte->relid = InvalidOid;
+ 			rte->subquery = subquery;
+ 			rte->security_barrier = true;
+ 			rte->eref = makeAlias(rte->eref->aliasname, colnames);
+ 			rte->inh = false;			/* must not be set for a subquery */
+ 
+ 			/* the permissions checks have now been move down */
+ 			rte->requiredPerms = 0;
+ 			rte->checkAsUser = InvalidOid;
+ 			rte->selectedCols = NULL;
+ 			rte->modifiedCols = NULL;
+ 
+ 			/*
+ 			 * Update any varattnos in the main query that refer to this RTE,
+ 			 * using the entries from the inverse targetlist.
+ 			 */
+ 			return (Query *) ResolveNew((Node *) parsetree,
+ 										rt_index,
+ 										0,
+ 										rte,
+ 										inverse_targetlist,
+ 										parsetree->commandType,
+ 										rt_index,
+ 										&parsetree->hasSubLinks);
+ 
+ 		case RTE_SUBQUERY:
+ 			/*
+ 			 * Build a new subquery that includes all the same columns as the
+ 			 * original subquery.
+ 			 */
+ 			foreach(cell, rte->subquery->targetList)
+ 			{
+ 				tle = (TargetEntry *) lfirst(cell);
+ 				var = makeVarFromTargetEntry(1, tle);
+ 
+ 				tle = makeTargetEntry((Expr *) var,
+ 									  list_length(targetlist) + 1,
+ 									  pstrdup(tle->resname),
+ 									  tle->resjunk);
+ 				targetlist = lappend(targetlist, tle);
+ 			}
+ 
+ 			subquery = makeNode(Query);
+ 			subquery->commandType = CMD_SELECT;
+ 			subquery->querySource = QSRC_INSTEAD_RULE;
+ 			subquery->targetList = targetlist;
+ 
+ 			subrte = makeNode(RangeTblEntry);
+ 			subrte->rtekind = RTE_SUBQUERY;
+ 			subrte->subquery = rte->subquery;
+ 			subrte->security_barrier = rte->security_barrier;
+ 			subrte->eref = copyObject(rte->eref);
+ 			subrte->inFromCl = true;
+ 			subquery->rtable = list_make1(subrte);
+ 
+ 			subrtr = makeNode(RangeTblRef);
+ 			subrtr->rtindex = 1;
+ 			subquery->jointree = makeFromExpr(list_make1(subrtr), qual);
+ 			subquery->hasSubLinks = checkExprHasSubLink(qual);
+ 
+ 			rte->subquery = subquery;
+ 			rte->security_barrier = true;
+ 
+ 			return parsetree;
+ 
+ 		default:
+ 			elog(ERROR, "invalid range table entry for security barrier qual");
+ 	}
+ 
+ 	return NULL;
+ }
+ 
+ 
+ /*
+  * rewriteSecurityQualsOnSubLink -
+  *	  Apply rewriteSecurityQuals() to each SubLink (subselect in expression)
+  *	  found in the given tree.
+  *
+  * NOTE: although this has the form of a walker, we cheat and modify the
+  * SubLink nodes in-place.  This is safe because we are not descending into
+  * subqueries, so no parts of the tree we are modifying are being traversed.
+  *
+  * Each SubLink subselect is replaced with a possibly-rewritten subquery.
+  */
+ static bool
+ rewriteSecurityQualsOnSubLink(Node *node, void *ctx)
+ {
+ 	if (node == NULL)
+ 		return false;
+ 	if (IsA(node, SubLink))
+ 	{
+ 		SubLink	   *sub = (SubLink *) node;
+ 
+ 		sub->subselect = (Node *)
+ 			rewriteSecurityQuals((Query *) sub->subselect);
+ 		/* Fall through to process lefthand args of SubLink */
+ 	}
+ 
+ 	/*
+ 	 * Do NOT recurse into Query nodes, because rewriteSecurityQuals already
+ 	 * processed all subqueries in the rtable and cteList.
+ 	 */
+ 	return expression_tree_walker(node, rewriteSecurityQualsOnSubLink, ctx);
+ }
+ 
+ 
+ /*
+  * rewriteSecurityQuals -
+  *	  rewrites any security barrier quals on RTEs in the query, turning them
+  *	  into subqueries to allow the planner to enforce them before any user
+  *	  quals where necessary. Currently such security barrier quals can only
+  *	  have come from automatically updatable security barrier views.
+  *
+  * We do this at the end of the rewriting process (after any SELECT rules
+  * have been applied) so that the new security barrier subqueries wrap any
+  * remaining views after they are expanded.
+  *
+  * Any given RTE may have multiple security barrier quals in a list, from
+  * which we create a set of nested subqueries to isolate each security barrier
+  * from the others, providing protection against malicious user security
+  * barriers.  The first item in the list represents the innermost subquery.
+  */
+ static Query *
+ rewriteSecurityQuals(Query *parsetree)
+ {
+ 	ListCell   *l;
+ 	int			rt_index;
+ 
+ 	/*
+ 	 * Process each RTE in the rtable list.  Security barrier quals are
+ 	 * initially only added to the result relation, but subsequent rules
+ 	 * may change that, so they may be anywhere.
+ 	 *
+ 	 * Note that this is deliberately not a foreach loop, since the whole
+ 	 * parsetree may be mutated each time through the loop.
+ 	 */
+ 	rt_index = 0;
+ 	while (rt_index < list_length(parsetree->rtable))
+ 	{
+ 		RangeTblEntry *rte;
+ 		bool		is_result_relation;
+ 		int			qual_idx;
+ 
+ 		++rt_index;
+ 		rte = rt_fetch(rt_index, parsetree->rtable);
+ 
+ 		if (rte->securityQuals == NIL)
+ 			continue;
+ 
+ 		/*
+ 		 * Ignore any RTEs that aren't used in the query (such RTEs may be
+ 		 * present for permissions checks).
+ 		 */
+ 		if (rt_index != parsetree->resultRelation &&
+ 			!rangeTableEntry_used((Node *) parsetree, rt_index, 0))
+ 			continue;
+ 
+ 		/*
+ 		 * Recursively process any security barrier quals in subquery RTEs
+ 		 * before processing any at this query level.
+ 		 */
+ 		if (rte->rtekind == RTE_SUBQUERY)
+ 			rte->subquery = rewriteSecurityQuals(rte->subquery);
+ 
+ 		/*
+ 		 * If this RTE is the target then we need to make a copy of it before
+ 		 * expanding it.  The unexpanded copy will become the new target, and
+ 		 * the expanded RTE will be the source of rows to update/delete.
+ 		 */
+ 		is_result_relation = rt_index == parsetree->resultRelation;
+ 		if (is_result_relation)
+ 		{
+ 			RangeTblEntry *newrte = copyObject(rte);
+ 			parsetree->rtable = lappend(parsetree->rtable, newrte);
+ 			parsetree->resultRelation = list_length(parsetree->rtable);
+ 
+ 			/*
+ 			 * Wipe out any copied security quals on the new target to prevent
+ 			 * infinite recursion.
+ 			 */
+ 			newrte->securityQuals = NIL;
+ 
+ 			/*
+ 			 * There's no need to do permissions checks twice, so wipe out the
+ 			 * permissions info for the original RTE (we prefer to keep the
+ 			 * bits set on the result RTE).
+ 			 */
+ 			rte->requiredPerms = 0;
+ 			rte->checkAsUser = InvalidOid;
+ 			rte->selectedCols = NULL;
+ 			rte->modifiedCols = NULL;
+ 
+ 			/*
+ 			 * For the most part, Vars referencing the original relation
+ 			 * should remain as as they are, meaning that they implicitly
+ 			 * represent OLD values.  But in the RETURNING list if any, we
+ 			 * want such Vars to represent NEW values, so change them to
+ 			 * reference the new RTE.
+ 			 *
+ 			 * Since ChangeVarNodes scribbles on the tree in-place, copy the
+ 			 * RETURNING list first for safety.
+ 			 */
+ 			parsetree->returningList = copyObject(parsetree->returningList);
+ 			ChangeVarNodes((Node *) parsetree->returningList, rt_index,
+ 						   parsetree->resultRelation, 0);
+ 		}
+ 
+ 		/*
+ 		 * Process each security qual in turn, starting with the innermost
+ 		 * one and working outwards.
+ 		 *
+ 		 * Note that we can't use a foreach loop here because the whole
+ 		 * parsetree may be mutated each time through the loop.  For the same
+ 		 * reason we must re-fetch the RTE each time.
+ 		 */
+ 		qual_idx = 0;
+ 		while (qual_idx < list_length(rte->securityQuals))
+ 		{
+ 			Node   *qual = (Node *) list_nth(rte->securityQuals, qual_idx);
+ 
+ 			parsetree = rewriteSecurityQual(parsetree, rt_index,
+ 											is_result_relation, qual);
+ 
+ 			/* re-fetch the RTE in case it has been re-written */
+ 			rte = rt_fetch(rt_index, parsetree->rtable);
+ 
+ 			qual_idx++;
+ 		}
+ 		rte->securityQuals = NIL;
+ 	}
+ 
+ 	/* Recurse into subqueries in WITH */
+ 	foreach(l, parsetree->cteList)
+ 	{
+ 		CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
+ 
+ 		cte->ctequery = (Node *)
+ 			rewriteSecurityQuals((Query *) cte->ctequery);
+ 	}
+ 
+ 	/*
+ 	 * Recurse into sublink subqueries too, without descending into the rtable
+ 	 * or the cteList, which we have already processed.
+ 	 */
+ 	if (parsetree->hasSubLinks)
+ 		query_tree_walker(parsetree, rewriteSecurityQualsOnSubLink, NULL,
+ 						  QTW_IGNORE_RC_SUBQUERIES);
+ 
+ 	return parsetree;
+ }
+ 
+ 
+ /*
   * RewriteQuery -
   *	  rewrites the query and apply the rules again on the queries rewritten
   *
*************** RewriteQuery(Query *parsetree, List *rew
*** 1842,1847 ****
--- 2658,2664 ----
  	bool		instead = false;
  	bool		returning = false;
  	Query	   *qual_product = NULL;
+ 	List	   *product_queries = NIL;
  	List	   *rewritten = NIL;
  	ListCell   *lc1;
  
*************** RewriteQuery(Query *parsetree, List *rew
*** 1993,2001 ****
  						   result_relation, parsetree);
  
  		if (locks != NIL)
- 		{
- 			List	   *product_queries;
- 
  			product_queries = fireRules(parsetree,
  										result_relation,
  										event,
--- 2810,2815 ----
*************** RewriteQuery(Query *parsetree, List *rew
*** 2004,2009 ****
--- 2818,2848 ----
  										&returning,
  										&qual_product);
  
+ 		/*
+ 		 * If there are no unqualified INSTEAD rules, and the target relation
+ 		 * is a view without any INSTEAD OF triggers, then we have a problem
+ 		 * unless it can be automatically updated.
+ 		 *
+ 		 * If we can automatically update the view, then we do so here and add
+ 		 * the resulting query to the product queries list, so that it gets
+ 		 * recursively rewritten if necessary.  We mark this as an unqualified
+ 		 * INSTEAD to prevent the original query from being executed.  Note
+ 		 * also that if this succeeds it will have rewritten any returning
+ 		 * list too.
+ 		 */
+ 		if (!instead && rt_entry_relation->rd_rel->relkind == RELKIND_VIEW)
+ 		{
+ 			Query  *query = qual_product ? qual_product : parsetree;
+ 			Query  *newquery = rewriteTargetView(query, rt_entry_relation);
+ 
+ 			if (newquery != NULL)
+ 			{
+ 				product_queries = lappend(product_queries, newquery);
+ 				instead = true;
+ 				returning = true;
+ 			}
+ 		}
+ 
  			/*
  			 * If we got any product queries, recursively rewrite them --- but
  			 * first check for recursion!
*************** RewriteQuery(Query *parsetree, List *rew
*** 2040,2046 ****
  
  				rewrite_events = list_delete_first(rewrite_events);
  			}
- 		}
  
  		/*
  		 * If there is an INSTEAD, and the original query has a RETURNING, we
--- 2879,2884 ----
*************** QueryRewrite(Query *parsetree)
*** 2181,2187 ****
  	/*
  	 * Step 2
  	 *
! 	 * Apply all the RIR rules on each query
  	 *
  	 * This is also a handy place to mark each query with the original queryId
  	 */
--- 3019,3026 ----
  	/*
  	 * Step 2
  	 *
! 	 * Apply all the RIR rules on each query, and then expand any security
! 	 * quals that apply to RTEs in the query.
  	 *
  	 * This is also a handy place to mark each query with the original queryId
  	 */
*************** QueryRewrite(Query *parsetree)
*** 2191,2196 ****
--- 3030,3036 ----
  		Query	   *query = (Query *) lfirst(l);
  
  		query = fireRIRrules(query, NIL, false);
+ 		query = rewriteSecurityQuals(query);
  
  		query->queryId = input_query_id;
  
*************** QueryRewrite(Query *parsetree)
*** 2245,2247 ****
--- 3085,3212 ----
  
  	return results;
  }
+ 
+ 
+ /*
+  * is_relation_updatable - test if the specified relation is updatable.
+  *
+  * This is used for the information schema views, which have separate concepts
+  * of "updatable" and "trigger updatable" although their precise definitions
+  * are not entirely clear in the SQL standard.  We take "updatable" to mean
+  * that the relation can be updated without the need for triggers (either
+  * because it has a suitable update rule, or because it is simple enough to be
+  * automatically updated), and "trigger updatable" means it has a suitable
+  * INSTEAD OF trigger.
+  *
+  * In the case of an automatically updatable view, the base relation must also
+  * be updatable, which we take to mean the base relation is either updatable
+  * or trigger updatable.
+  */
+ static bool
+ is_relation_updatable(Oid oid, CmdType event, bool includeTriggers)
+ {
+ 	Relation	rel;
+ 	RuleLock   *rulelocks;
+ 
+ 	rel = heap_open(oid, AccessShareLock);
+ 
+ 	/* Look for an unconditional DO INSTEAD rule */
+ 	rulelocks = rel->rd_rules;
+ 	if (rulelocks != NULL)
+ 	{
+ 		int		i;
+ 
+ 		for (i = 0; i < rulelocks->numLocks; i++)
+ 		{
+ 			if (rulelocks->rules[i]->event == event &&
+ 				rulelocks->rules[i]->isInstead &&
+ 				rulelocks->rules[i]->qual == NULL)
+ 			{
+ 				heap_close(rel, AccessShareLock);
+ 				return true;
+ 			}
+ 		}
+ 	}
+ 
+ 	/* Maybe also check for an INSTEAD OF trigger */
+ 	if (includeTriggers)
+ 	{
+ 		TriggerDesc *trigDesc = rel->trigdesc;
+ 		bool	updatable = false;
+ 
+ 		switch (event)
+ 		{
+ 			case CMD_INSERT:
+ 				updatable = trigDesc && trigDesc->trig_insert_instead_row;
+ 				break;
+ 
+ 			case CMD_UPDATE:
+ 				updatable = trigDesc && trigDesc->trig_update_instead_row;
+ 				break;
+ 
+ 			case CMD_DELETE:
+ 				updatable = trigDesc && trigDesc->trig_delete_instead_row;
+ 				break;
+ 
+ 			default:
+ 				elog(ERROR, "unrecognized CmdType: %d", (int) event);
+ 				break;
+ 		}
+ 
+ 		if (updatable)
+ 		{
+ 			heap_close(rel, AccessShareLock);
+ 			return true;
+ 		}
+ 	}
+ 
+ 	/* Check if this is an automatically updatable view */
+ 	if (rel->rd_rel->relkind == RELKIND_VIEW &&
+ 		test_auto_update_view(rel) == NULL)
+ 	{
+ 		Query	   *viewquery;
+ 		RangeTblRef *rtr;
+ 		RangeTblEntry *base_rte;
+ 		Oid			baseoid;
+ 
+ 		/* The base relation must also be updatable */
+ 		viewquery = get_view_query(rel);
+ 		rtr = (RangeTblRef *) linitial(viewquery->jointree->fromlist);
+ 		base_rte = rt_fetch(rtr->rtindex, viewquery->rtable);
+ 
+ 		if (base_rte->relkind == RELKIND_RELATION)
+ 		{
+ 			/* Tables are always updatable */
+ 			heap_close(rel, AccessShareLock);
+ 			return true;
+ 		}
+ 		else
+ 		{
+ 			/* Do a recursive check for any other kind of base relation */
+ 			baseoid = base_rte->relid;
+ 			heap_close(rel, AccessShareLock);
+ 			return is_relation_updatable(baseoid, event, true);
+ 		}
+ 	}
+ 
+ 	/* If we reach here, the relation is not updatable */
+ 	heap_close(rel, AccessShareLock);
+ 	return false;
+ }
+ 
+ Datum
+ pg_is_view_updatable(PG_FUNCTION_ARGS)
+ {
+ 	Oid			viewoid = PG_GETARG_OID(0);
+ 
+ 	PG_RETURN_BOOL(is_relation_updatable(viewoid, CMD_UPDATE, false) &&
+ 				   is_relation_updatable(viewoid, CMD_DELETE, false));
+ }
+ 
+ Datum
+ pg_is_view_insertable(PG_FUNCTION_ARGS)
+ {
+ 	Oid			viewoid = PG_GETARG_OID(0);
+ 
+ 	PG_RETURN_BOOL(is_relation_updatable(viewoid, CMD_INSERT, false));
+ }
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
new file mode 100644
index ef04c34..d9bd5b4
*** a/src/backend/rewrite/rewriteManip.c
--- b/src/backend/rewrite/rewriteManip.c
***************
*** 13,18 ****
--- 13,19 ----
   */
  #include "postgres.h"
  
+ #include "access/sysattr.h"
  #include "catalog/pg_type.h"
  #include "nodes/makefuncs.h"
  #include "nodes/nodeFuncs.h"
*************** ResolveNew(Node *node, int target_varno,
*** 1443,1445 ****
--- 1444,1486 ----
  								 (void *) &context,
  								 outer_hasSubLinks);
  }
+ 
+ 
+ /*
+  * adjust_column_set - replace columns in a set with entries from a targetlist
+  *
+  * Non-system columns in the set are replaced by the entry with matching resno
+  * from targetlist, and system columns are left unchanged.  This is used for
+  * simply updatable views to map permissions checks on the view columns onto
+  * the matching columns in the underlying base relation.
+  */
+ Bitmapset *
+ adjust_column_set(Bitmapset *cols, List *targetlist)
+ {
+ 	Bitmapset  *tmpcols = bms_copy(cols);
+ 	Bitmapset  *result = NULL;
+ 	AttrNumber	col;
+ 
+ 	while ((col = bms_first_member(tmpcols)) >= 0)
+ 	{
+ 		AttrNumber	attno = col + FirstLowInvalidHeapAttributeNumber;
+ 
+ 		if (attno <= 0)
+ 			/* system column - leave it unchanged */
+ 			result = bms_add_member(result, col);
+ 		else if (attno <= list_length(targetlist))
+ 		{
+ 			/* non-system column - update it from the targetlist */
+ 			TargetEntry *tle = get_tle_by_resno(targetlist, attno);
+ 			if (tle != NULL && IsA(tle->expr, Var))
+ 			{
+ 				Var	   *var = (Var *) tle->expr;
+ 				result = bms_add_member(result,
+ 					var->varattno - FirstLowInvalidHeapAttributeNumber);
+ 			}
+ 		}
+ 	}
+ 	bms_free(tmpcols);
+ 
+ 	return result;
+ }
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
new file mode 100644
index 77a3b41..c0673b7
*** a/src/include/catalog/pg_proc.h
--- b/src/include/catalog/pg_proc.h
*************** DATA(insert OID = 2232 (  pg_get_functio
*** 1958,1963 ****
--- 1958,1967 ----
  DESCR("identity argument list of a function");
  DATA(insert OID = 2165 (  pg_get_function_result	   PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 25 "26" _null_ _null_ _null_ _null_ pg_get_function_result _null_ _null_ _null_ ));
  DESCR("result type of a function");
+ DATA(insert OID = 3170 (  pg_is_view_updatable	PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 16 "26" _null_ _null_ _null_ _null_ pg_is_view_updatable _null_ _null_ _null_ ));
+ DESCR("whether or not a view is updatable");
+ DATA(insert OID = 3171 (  pg_is_view_insertable	PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 16 "26" _null_ _null_ _null_ _null_ pg_is_view_insertable _null_ _null_ _null_ ));
+ DESCR("whether or not a view is insertable");
  
  DATA(insert OID = 1686 (  pg_get_keywords		PGNSP PGUID 12 10 400 0 0 f f f f t t s 0 0 2249 "" "{25,18,25}" "{o,o,o}" "{word,catcode,catdesc}" _null_ pg_get_keywords _null_ _null_ _null_ ));
  DESCR("list of SQL keywords");
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
new file mode 100644
index 19178b5..08eebd5
*** a/src/include/nodes/parsenodes.h
--- b/src/include/nodes/parsenodes.h
*************** typedef struct RangeTblEntry
*** 765,770 ****
--- 765,771 ----
  	Oid			checkAsUser;	/* if valid, check access as this role */
  	Bitmapset  *selectedCols;	/* columns needing SELECT permission */
  	Bitmapset  *modifiedCols;	/* columns needing INSERT/UPDATE permission */
+ 	List	   *securityQuals;	/* any security barrier quals to apply */
  } RangeTblEntry;
  
  /*
diff --git a/src/include/rewrite/rewriteHandler.h b/src/include/rewrite/rewriteHandler.h
new file mode 100644
index 50625d4..9879c5c
*** a/src/include/rewrite/rewriteHandler.h
--- b/src/include/rewrite/rewriteHandler.h
***************
*** 20,24 ****
--- 20,26 ----
  extern List *QueryRewrite(Query *parsetree);
  extern void AcquireRewriteLocks(Query *parsetree, bool forUpdatePushedDown);
  extern Node *build_column_default(Relation rel, int attrno);
+ extern Datum pg_is_view_updatable(PG_FUNCTION_ARGS);
+ extern Datum pg_is_view_insertable(PG_FUNCTION_ARGS);
  
  #endif   /* REWRITEHANDLER_H */
diff --git a/src/include/rewrite/rewriteManip.h b/src/include/rewrite/rewriteManip.h
new file mode 100644
index e13331d..4e0b867
*** a/src/include/rewrite/rewriteManip.h
--- b/src/include/rewrite/rewriteManip.h
*************** extern Node *ResolveNew(Node *node, int
*** 74,77 ****
--- 74,79 ----
  		   List *targetlist, int event, int update_varno,
  		   bool *outer_hasSubLinks);
  
+ extern Bitmapset *adjust_column_set(Bitmapset *cols, List *targetlist);
+ 
  #endif   /* REWRITEMANIP_H */
diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
new file mode 100644
index b5af066..5439120
*** a/src/test/regress/expected/triggers.out
--- b/src/test/regress/expected/triggers.out
*************** DROP TABLE min_updates_test_oids;
*** 820,839 ****
  -- Test triggers on views
  --
  CREATE VIEW main_view AS SELECT a, b FROM main_table;
- -- Updates should fail without rules or triggers
- INSERT INTO main_view VALUES (1,2);
- ERROR:  cannot insert into view "main_view"
- HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
- UPDATE main_view SET b = 20 WHERE a = 50;
- ERROR:  cannot update view "main_view"
- HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
- DELETE FROM main_view WHERE a = 50;
- ERROR:  cannot delete from view "main_view"
- HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
- -- Should fail even when there are no matching rows
- DELETE FROM main_view WHERE a = 51;
- ERROR:  cannot delete from view "main_view"
- HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
  -- VIEW trigger function
  CREATE OR REPLACE FUNCTION view_trigger() RETURNS trigger
  LANGUAGE plpgsql AS $$
--- 820,825 ----
diff --git a/src/test/regress/expected/updatable_views.out b/src/test/regress/expected/updatable_views.out
new file mode 100644
index ...3c0a424
*** a/src/test/regress/expected/updatable_views.out
--- b/src/test/regress/expected/updatable_views.out
***************
*** 0 ****
--- 1,744 ----
+ --
+ -- UPDATABLE VIEWS
+ --
+ CREATE TABLE base_tbl (a int PRIMARY KEY, b text DEFAULT 'Unspecified');
+ INSERT INTO base_tbl VALUES (1, 'Row 1');
+ INSERT INTO base_tbl VALUES (2, 'Row 2');
+ -- non-updatable views
+ CREATE VIEW ro_view1 AS SELECT DISTINCT a, b FROM base_tbl; -- DISTINCT not supported
+ CREATE VIEW ro_view2 AS SELECT a, b FROM base_tbl GROUP BY a, b; -- GROUP BY not supported
+ CREATE VIEW ro_view3 AS SELECT 1 FROM base_tbl HAVING max(a) > 0; -- HAVING not supported
+ CREATE VIEW ro_view4 AS SELECT count(*) FROM base_tbl; -- Aggregate functions not supported
+ CREATE VIEW ro_view5 AS SELECT a, rank() OVER() FROM base_tbl; -- Window functions not supported
+ CREATE VIEW ro_view6 AS SELECT a, b FROM base_tbl UNION SELECT -a, b FROM base_tbl; -- Set ops not supported
+ CREATE VIEW ro_view7 AS WITH t AS (SELECT a, b FROM base_tbl) SELECT * FROM t; -- WITH [RECURSIVE] not supported
+ CREATE VIEW ro_view8 AS SELECT a, b FROM base_tbl ORDER BY a OFFSET 1; -- OFFSET not supported
+ CREATE VIEW ro_view9 AS SELECT a, b FROM base_tbl ORDER BY a LIMIT 1; -- LIMIT not supported
+ CREATE VIEW ro_view10 AS SELECT 1 AS a; -- No base relations
+ CREATE VIEW ro_view11 AS SELECT b1.a, b2.b FROM base_tbl b1, base_tbl b2; -- Multiple base relations
+ CREATE VIEW ro_view12 AS SELECT * FROM generate_series(1, 10) AS g(a); -- SRF in rangetable
+ CREATE VIEW ro_view13 AS SELECT a, b FROM (SELECT * FROM base_tbl) AS t; -- Subselect in rangetable
+ CREATE VIEW ro_view14 AS SELECT ctid FROM base_tbl; -- System columns not supported
+ CREATE VIEW ro_view15 AS SELECT a, upper(b) FROM base_tbl; -- Expression/function in targetlist
+ CREATE VIEW ro_view16 AS SELECT a, b, a AS aa FROM base_tbl; -- Repeated column
+ CREATE VIEW ro_view17 AS SELECT * FROM ro_view1; -- Base relation not updatable
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'ro_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  ro_view1   | NO           | NO
+  ro_view10  | NO           | NO
+  ro_view11  | NO           | NO
+  ro_view12  | NO           | NO
+  ro_view13  | NO           | NO
+  ro_view14  | NO           | NO
+  ro_view15  | NO           | NO
+  ro_view16  | NO           | NO
+  ro_view17  | NO           | NO
+  ro_view2   | NO           | NO
+  ro_view3   | NO           | NO
+  ro_view4   | NO           | NO
+  ro_view5   | NO           | NO
+  ro_view6   | NO           | NO
+  ro_view7   | NO           | NO
+  ro_view8   | NO           | NO
+  ro_view9   | NO           | NO
+ (17 rows)
+ 
+ DELETE FROM ro_view1;
+ ERROR:  cannot delete from view "ro_view1"
+ DETAIL:  Views containing DISTINCT are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ DELETE FROM ro_view2;
+ ERROR:  cannot delete from view "ro_view2"
+ DETAIL:  Views containing GROUP BY are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ DELETE FROM ro_view3;
+ ERROR:  cannot delete from view "ro_view3"
+ DETAIL:  Views containing HAVING are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ DELETE FROM ro_view4;
+ ERROR:  cannot delete from view "ro_view4"
+ DETAIL:  Views containing aggregates are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ DELETE FROM ro_view5;
+ ERROR:  cannot delete from view "ro_view5"
+ DETAIL:  Views containing window functions are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ DELETE FROM ro_view6;
+ ERROR:  cannot delete from view "ro_view6"
+ DETAIL:  Views containing UNION, INTERSECT or EXCEPT are not updatable.
+ HINT:  You need an unconditional ON DELETE DO INSTEAD rule or an INSTEAD OF DELETE trigger.
+ UPDATE ro_view7 SET a=a+1;
+ ERROR:  cannot update view "ro_view7"
+ DETAIL:  Views containing WITH [RECURSIVE] are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ UPDATE ro_view8 SET a=a+1;
+ ERROR:  cannot update view "ro_view8"
+ DETAIL:  Views containing OFFSET or LIMIT are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ UPDATE ro_view9 SET a=a+1;
+ ERROR:  cannot update view "ro_view9"
+ DETAIL:  Views containing OFFSET or LIMIT are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ UPDATE ro_view10 SET a=a+1;
+ ERROR:  cannot update view "ro_view10"
+ DETAIL:  Views with no base relations are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ UPDATE ro_view11 SET a=a+1;
+ ERROR:  cannot update view "ro_view11"
+ DETAIL:  Views with multiple base relations are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ UPDATE ro_view12 SET a=a+1;
+ ERROR:  cannot update view "ro_view12"
+ DETAIL:  Views that are not based on tables or views are not updatable.
+ HINT:  You need an unconditional ON UPDATE DO INSTEAD rule or an INSTEAD OF UPDATE trigger.
+ INSERT INTO ro_view13 VALUES (3, 'Row 3');
+ ERROR:  cannot insert into view "ro_view13"
+ DETAIL:  Views that are not based on tables or views are not updatable.
+ HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
+ INSERT INTO ro_view14 VALUES (null);
+ ERROR:  cannot insert into view "ro_view14"
+ DETAIL:  Views that refer to system columns are not updatable.
+ HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
+ INSERT INTO ro_view15 VALUES (3, 'ROW 3');
+ ERROR:  cannot insert into view "ro_view15"
+ DETAIL:  Views with columns that are not simple references to columns in the base relation are not updatable.
+ HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
+ INSERT INTO ro_view16 VALUES (3, 'Row 3', 3);
+ ERROR:  cannot insert into view "ro_view16"
+ DETAIL:  Views that refer to the same column more than once are not updatable.
+ HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
+ INSERT INTO ro_view17 VALUES (3, 'ROW 3');
+ ERROR:  cannot insert into view "ro_view1"
+ DETAIL:  Views containing DISTINCT are not updatable.
+ HINT:  You need an unconditional ON INSERT DO INSTEAD rule or an INSTEAD OF INSERT trigger.
+ DROP VIEW ro_view1, ro_view2, ro_view3, ro_view4, ro_view5,
+           ro_view6, ro_view7, ro_view8, ro_view9, ro_view10,
+           ro_view11, ro_view12, ro_view13, ro_view14, ro_view15,
+           ro_view16, ro_view17;
+ -- simple updatable view
+ CREATE VIEW rw_view1 AS SELECT * FROM base_tbl;
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view1';
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view1   | YES          | YES
+ (1 row)
+ 
+ INSERT INTO rw_view1 VALUES (3, 'Row 3');
+ INSERT INTO rw_view1 (a) VALUES (4);
+ UPDATE rw_view1 SET a=0 WHERE a=1;
+ DELETE FROM rw_view1 WHERE b='Row 2';
+ SELECT * FROM base_tbl;
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+ (3 rows)
+ 
+ EXPLAIN (costs off) UPDATE rw_view1 SET a=1 WHERE a=0;
+                     QUERY PLAN                    
+ --------------------------------------------------
+  Update on base_tbl
+    ->  Index Scan using base_tbl_pkey on base_tbl
+          Index Cond: (a = 0)
+ (3 rows)
+ 
+ EXPLAIN (costs off) DELETE FROM rw_view1 WHERE a=0;
+                     QUERY PLAN                    
+ --------------------------------------------------
+  Delete on base_tbl
+    ->  Index Scan using base_tbl_pkey on base_tbl
+          Index Cond: (a = 0)
+ (3 rows)
+ 
+ -- view on top of view hiding private data
+ INSERT INTO base_tbl VALUES (-1, 'Private data');
+ CREATE VIEW rw_view2 AS SELECT * FROM rw_view1 WHERE b !~* 'private';
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view2';
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view2   | YES          | YES
+ (1 row)
+ 
+ SELECT * FROM base_tbl;
+  a  |      b       
+ ----+--------------
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+  -1 | Private data
+ (4 rows)
+ 
+ SELECT * FROM rw_view2;
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+ (3 rows)
+ 
+ INSERT INTO rw_view2 VALUES (5, 'Row 5');
+ INSERT INTO rw_view2 (a) VALUES (6);
+ SELECT * FROM rw_view2;
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+  5 | Row 5
+  6 | Unspecified
+ (5 rows)
+ 
+ UPDATE rw_view2 SET b='Row 6' WHERE a=6;
+ DELETE FROM rw_view2 WHERE a=5;
+ SELECT * FROM rw_view2;
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+  6 | Row 6
+ (4 rows)
+ 
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=1 WHERE a=0;
+                     QUERY PLAN                    
+ --------------------------------------------------
+  Update on base_tbl
+    ->  Index Scan using base_tbl_pkey on base_tbl
+          Index Cond: (a = 0)
+          Filter: (b !~* 'private'::text)
+ (4 rows)
+ 
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE a=0;
+                     QUERY PLAN                    
+ --------------------------------------------------
+  Delete on base_tbl
+    ->  Index Scan using base_tbl_pkey on base_tbl
+          Index Cond: (a = 0)
+          Filter: (b !~* 'private'::text)
+ (4 rows)
+ 
+ -- snoop on private value
+ CREATE FUNCTION snoop(a int, b text)
+ RETURNS boolean AS
+ $$
+ BEGIN
+   RAISE NOTICE 'a=%, b=%', a, b;
+   RETURN true;
+ END;
+ $$
+ LANGUAGE plpgsql COST 0.000001;
+ SELECT * FROM rw_view2 WHERE snoop(a,b);
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=-1, b=Private data
+ NOTICE:  a=6, b=Row 6
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+  6 | Row 6
+ (4 rows)
+ 
+ UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=-1, b=Private data
+ NOTICE:  a=6, b=Row 6
+ DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ NOTICE:  a=-1, b=Private data
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=6, b=Row 6
+ EXPLAIN (costs off) SELECT * FROM rw_view2 WHERE snoop(a,b);
+                      QUERY PLAN                      
+ -----------------------------------------------------
+  Seq Scan on base_tbl
+    Filter: (snoop(a, b) AND (b !~* 'private'::text))
+ (2 rows)
+ 
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+                         QUERY PLAN                         
+ -----------------------------------------------------------
+  Update on base_tbl
+    ->  Seq Scan on base_tbl
+          Filter: (snoop(a, b) AND (b !~* 'private'::text))
+ (3 rows)
+ 
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+                            QUERY PLAN                            
+ -----------------------------------------------------------------
+  Delete on base_tbl
+    ->  Seq Scan on base_tbl
+          Filter: ((NOT snoop(a, b)) AND (b !~* 'private'::text))
+ (3 rows)
+ 
+ -- security barrier view prevents snooping
+ ALTER VIEW rw_view2 SET (security_barrier = true);
+ SELECT * FROM rw_view2 WHERE snoop(a,b);
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=6, b=Row 6
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+  6 | Row 6
+ (4 rows)
+ 
+ UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=6, b=Row 6
+ DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=6, b=Row 6
+ EXPLAIN (costs off) SELECT * FROM rw_view2 WHERE snoop(a,b);
+                QUERY PLAN                
+ -----------------------------------------
+  Subquery Scan on rw_view2
+    Filter: snoop(rw_view2.a, rw_view2.b)
+    ->  Seq Scan on base_tbl
+          Filter: (b !~* 'private'::text)
+ (4 rows)
+ 
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+                      QUERY PLAN                      
+ -----------------------------------------------------
+  Update on base_tbl
+    ->  Subquery Scan on base_tbl
+          Filter: snoop(base_tbl.a, base_tbl.b)
+          ->  LockRows
+                ->  Seq Scan on base_tbl
+                      Filter: (b !~* 'private'::text)
+ (6 rows)
+ 
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+                      QUERY PLAN                      
+ -----------------------------------------------------
+  Delete on base_tbl
+    ->  Subquery Scan on base_tbl
+          Filter: (NOT snoop(base_tbl.a, base_tbl.b))
+          ->  LockRows
+                ->  Seq Scan on base_tbl
+                      Filter: (b !~* 'private'::text)
+ (6 rows)
+ 
+ -- security barrier view on top of security barrier view
+ CREATE VIEW rw_view3 AS SELECT * FROM rw_view2 WHERE snoop(a,b);
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view3';
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view3   | YES          | YES
+ (1 row)
+ 
+ SELECT * FROM rw_view3;
+ NOTICE:  a=3, b=Row 3
+ NOTICE:  a=4, b=Unspecified
+ NOTICE:  a=0, b=Row 1
+ NOTICE:  a=6, b=Row 6
+  a |      b      
+ ---+-------------
+  3 | Row 3
+  4 | Unspecified
+  0 | Row 1
+  6 | Row 6
+ (4 rows)
+ 
+ UPDATE rw_view3 SET a=a WHERE a=5;
+ DELETE FROM rw_view3 WHERE a=5;
+ EXPLAIN (costs off) SELECT * FROM rw_view3;
+                QUERY PLAN                
+ -----------------------------------------
+  Subquery Scan on rw_view2
+    Filter: snoop(rw_view2.a, rw_view2.b)
+    ->  Seq Scan on base_tbl
+          Filter: (b !~* 'private'::text)
+ (4 rows)
+ 
+ EXPLAIN (costs off) UPDATE rw_view3 SET a=a WHERE a=5;
+                           QUERY PLAN                          
+ --------------------------------------------------------------
+  Update on base_tbl
+    ->  Subquery Scan on base_tbl
+          Filter: snoop(base_tbl.a, base_tbl.b)
+          ->  LockRows
+                ->  Index Scan using base_tbl_pkey on base_tbl
+                      Index Cond: (a = 5)
+                      Filter: (b !~* 'private'::text)
+ (7 rows)
+ 
+ EXPLAIN (costs off) DELETE FROM rw_view3 WHERE a=5;
+                           QUERY PLAN                          
+ --------------------------------------------------------------
+  Delete on base_tbl
+    ->  Subquery Scan on base_tbl
+          Filter: snoop(base_tbl.a, base_tbl.b)
+          ->  LockRows
+                ->  Index Scan using base_tbl_pkey on base_tbl
+                      Index Cond: (a = 5)
+                      Filter: (b !~* 'private'::text)
+ (7 rows)
+ 
+ DROP VIEW rw_view1, rw_view2, rw_view3;
+ -- view on top of view with rules
+ CREATE VIEW rw_view1 AS SELECT * FROM base_tbl OFFSET 0; -- not updatable without rules/triggers
+ CREATE VIEW rw_view2 AS SELECT * FROM rw_view1;
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view1   | NO           | NO
+  rw_view2   | NO           | NO
+ (2 rows)
+ 
+ CREATE RULE rw_view1_ins_rule AS ON INSERT TO rw_view1
+   DO INSTEAD INSERT INTO base_tbl VALUES (NEW.a, NEW.b) RETURNING *;
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view1   | NO           | YES
+  rw_view2   | NO           | YES
+ (2 rows)
+ 
+ CREATE RULE rw_view1_upd_rule AS ON UPDATE TO rw_view1
+   DO INSTEAD UPDATE base_tbl SET b=NEW.b WHERE a=OLD.a RETURNING NEW.*;
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view1   | NO           | YES
+  rw_view2   | NO           | YES
+ (2 rows)
+ 
+ CREATE RULE rw_view1_del_rule AS ON DELETE TO rw_view1
+   DO INSTEAD DELETE FROM base_tbl WHERE a=OLD.a RETURNING OLD.*;
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into 
+ ------------+--------------+--------------------
+  rw_view1   | YES          | YES
+  rw_view2   | YES          | YES
+ (2 rows)
+ 
+ SELECT * FROM rw_view2;
+  a  |      b       
+ ----+--------------
+  -1 | Private data
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+   6 | Row 6
+ (5 rows)
+ 
+ INSERT INTO rw_view2 VALUES (7, 'Row 7') RETURNING *;
+  a |   b   
+ ---+-------
+  7 | Row 7
+ (1 row)
+ 
+ UPDATE rw_view2 SET b='Row seven' WHERE a=7 RETURNING *;
+  a |     b     
+ ---+-----------
+  7 | Row seven
+ (1 row)
+ 
+ SELECT * FROM rw_view2;
+  a  |      b       
+ ----+--------------
+  -1 | Private data
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+   6 | Row 6
+   7 | Row seven
+ (6 rows)
+ 
+ DELETE FROM rw_view2 WHERE a=7 RETURNING *;
+  a |     b     
+ ---+-----------
+  7 | Row seven
+ (1 row)
+ 
+ -- view on top of view with triggers
+ DROP RULE rw_view1_ins_rule ON rw_view1;
+ DROP RULE rw_view1_upd_rule ON rw_view1;
+ DROP RULE rw_view1_del_rule ON rw_view1;
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into | is_trigger_updatable | is_trigger_deletable | is_trigger_insertable_into 
+ ------------+--------------+--------------------+----------------------+----------------------+----------------------------
+  rw_view1   | NO           | NO                 | NO                   | NO                   | NO
+  rw_view2   | NO           | NO                 | NO                   | NO                   | NO
+ (2 rows)
+ 
+ CREATE FUNCTION rw_view1_trig_fn()
+ RETURNS trigger AS
+ $$
+ BEGIN
+   IF TG_OP = 'INSERT' THEN
+     INSERT INTO base_tbl VALUES (NEW.a, NEW.b);
+     RETURN NEW;
+   ELSIF TG_OP = 'UPDATE' THEN
+     UPDATE base_tbl SET b=NEW.b WHERE a=OLD.a;
+     RETURN NEW;
+   ELSIF TG_OP = 'DELETE' THEN
+     DELETE FROM base_tbl WHERE a=OLD.a;
+     RETURN OLD;
+   END IF;
+ END;
+ $$
+ LANGUAGE plpgsql;
+ CREATE TRIGGER rw_view1_ins_trig INSTEAD OF INSERT ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into | is_trigger_updatable | is_trigger_deletable | is_trigger_insertable_into 
+ ------------+--------------+--------------------+----------------------+----------------------+----------------------------
+  rw_view1   | NO           | NO                 | NO                   | NO                   | YES
+  rw_view2   | NO           | YES                | NO                   | NO                   | NO
+ (2 rows)
+ 
+ CREATE TRIGGER rw_view1_upd_trig INSTEAD OF UPDATE ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into | is_trigger_updatable | is_trigger_deletable | is_trigger_insertable_into 
+ ------------+--------------+--------------------+----------------------+----------------------+----------------------------
+  rw_view1   | NO           | NO                 | YES                  | NO                   | YES
+  rw_view2   | NO           | YES                | NO                   | NO                   | NO
+ (2 rows)
+ 
+ CREATE TRIGGER rw_view1_del_trig INSTEAD OF DELETE ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+  table_name | is_updatable | is_insertable_into | is_trigger_updatable | is_trigger_deletable | is_trigger_insertable_into 
+ ------------+--------------+--------------------+----------------------+----------------------+----------------------------
+  rw_view1   | NO           | NO                 | YES                  | YES                  | YES
+  rw_view2   | YES          | YES                | NO                   | NO                   | NO
+ (2 rows)
+ 
+ SELECT * FROM rw_view2;
+  a  |      b       
+ ----+--------------
+  -1 | Private data
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+   6 | Row 6
+ (5 rows)
+ 
+ INSERT INTO rw_view2 VALUES (7, 'Row 7') RETURNING *;
+  a |   b   
+ ---+-------
+  7 | Row 7
+ (1 row)
+ 
+ UPDATE rw_view2 SET b='Row seven' WHERE a=7 RETURNING *;
+  a |     b     
+ ---+-----------
+  7 | Row seven
+ (1 row)
+ 
+ SELECT * FROM rw_view2;
+  a  |      b       
+ ----+--------------
+  -1 | Private data
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+   6 | Row 6
+   7 | Row seven
+ (6 rows)
+ 
+ DELETE FROM rw_view2 WHERE a=7 RETURNING *;
+  a |     b     
+ ---+-----------
+  7 | Row seven
+ (1 row)
+ 
+ DROP VIEW rw_view1, rw_view2;
+ -- test whole row from view
+ CREATE VIEW rw_view1 AS SELECT b AS bb, a AS aa FROM base_tbl;
+ CREATE FUNCTION rw_view1_aa(x rw_view1)
+   RETURNS int AS $$ SELECT x.aa $$ LANGUAGE sql;
+ UPDATE rw_view1 v SET bb='Updated row 6' WHERE rw_view1_aa(v)=6
+   RETURNING rw_view1_aa(v), v.bb;
+  rw_view1_aa |      bb       
+ -------------+---------------
+            6 | Updated row 6
+ (1 row)
+ 
+ SELECT * FROM base_tbl;
+  a  |       b       
+ ----+---------------
+  -1 | Private data
+   3 | Row 3
+   4 | Unspecified
+   0 | Row 1
+   6 | Updated row 6
+ (5 rows)
+ 
+ EXPLAIN (costs off)
+ UPDATE rw_view1 v SET bb='Updated row 6' WHERE rw_view1_aa(v)=6
+   RETURNING rw_view1_aa(v), v.bb;
+                     QUERY PLAN                    
+ --------------------------------------------------
+  Update on base_tbl
+    ->  Index Scan using base_tbl_pkey on base_tbl
+          Index Cond: (a = 6)
+ (3 rows)
+ 
+ DROP FUNCTION rw_view1_aa(rw_view1);
+ DROP VIEW rw_view1;
+ DROP TABLE base_tbl;
+ -- permissions checks
+ CREATE USER view_user1;
+ CREATE USER view_user2;
+ SET SESSION AUTHORIZATION view_user1;
+ CREATE TABLE base_tbl(a int, b text, c float);
+ INSERT INTO base_tbl VALUES (1, 'Row 1', 1.0);
+ CREATE VIEW rw_view1 AS SELECT b AS bb, c AS cc, a AS aa FROM base_tbl;
+ INSERT INTO rw_view1 VALUES ('Row 2', 2.0, 2);
+ GRANT SELECT ON base_tbl TO view_user2;
+ GRANT SELECT ON rw_view1 TO view_user2;
+ GRANT UPDATE (a,c) ON base_tbl TO view_user2;
+ GRANT UPDATE (bb,cc) ON rw_view1 TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ SET SESSION AUTHORIZATION view_user2;
+ CREATE VIEW rw_view2 AS SELECT b AS bb, c AS cc, a AS aa FROM base_tbl;
+ SELECT * FROM base_tbl; -- ok
+  a |   b   | c 
+ ---+-------+---
+  1 | Row 1 | 1
+  2 | Row 2 | 2
+ (2 rows)
+ 
+ SELECT * FROM rw_view1; -- ok
+   bb   | cc | aa 
+ -------+----+----
+  Row 1 |  1 |  1
+  Row 2 |  2 |  2
+ (2 rows)
+ 
+ SELECT * FROM rw_view2; -- ok
+   bb   | cc | aa 
+ -------+----+----
+  Row 1 |  1 |  1
+  Row 2 |  2 |  2
+ (2 rows)
+ 
+ INSERT INTO base_tbl VALUES (3, 'Row 3', 3.0); -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ INSERT INTO rw_view1 VALUES ('Row 3', 3.0, 3); -- not allowed
+ ERROR:  permission denied for relation rw_view1
+ INSERT INTO rw_view2 VALUES ('Row 3', 3.0, 3); -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ UPDATE base_tbl SET a=a, c=c; -- ok
+ UPDATE base_tbl SET b=b; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ UPDATE rw_view1 SET bb=bb, cc=cc; -- ok
+ UPDATE rw_view1 SET aa=aa; -- not allowed
+ ERROR:  permission denied for relation rw_view1
+ UPDATE rw_view2 SET aa=aa, cc=cc; -- ok
+ UPDATE rw_view2 SET bb=bb; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ DELETE FROM base_tbl; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ DELETE FROM rw_view1; -- not allowed
+ ERROR:  permission denied for relation rw_view1
+ DELETE FROM rw_view2; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ RESET SESSION AUTHORIZATION;
+ SET SESSION AUTHORIZATION view_user1;
+ GRANT INSERT, DELETE ON base_tbl TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ SET SESSION AUTHORIZATION view_user2;
+ INSERT INTO base_tbl VALUES (3, 'Row 3', 3.0); -- ok
+ INSERT INTO rw_view1 VALUES ('Row 4', 4.0, 4); -- not allowed
+ ERROR:  permission denied for relation rw_view1
+ INSERT INTO rw_view2 VALUES ('Row 4', 4.0, 4); -- ok
+ DELETE FROM base_tbl WHERE a=1; -- ok
+ DELETE FROM rw_view1 WHERE aa=2; -- not allowed
+ ERROR:  permission denied for relation rw_view1
+ DELETE FROM rw_view2 WHERE aa=2; -- ok
+ SELECT * FROM base_tbl;
+  a |   b   | c 
+ ---+-------+---
+  3 | Row 3 | 3
+  4 | Row 4 | 4
+ (2 rows)
+ 
+ RESET SESSION AUTHORIZATION;
+ SET SESSION AUTHORIZATION view_user1;
+ REVOKE INSERT, DELETE ON base_tbl FROM view_user2;
+ GRANT INSERT, DELETE ON rw_view1 TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ SET SESSION AUTHORIZATION view_user2;
+ INSERT INTO base_tbl VALUES (5, 'Row 5', 5.0); -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ INSERT INTO rw_view1 VALUES ('Row 5', 5.0, 5); -- ok
+ INSERT INTO rw_view2 VALUES ('Row 6', 6.0, 6); -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ DELETE FROM base_tbl WHERE a=3; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ DELETE FROM rw_view1 WHERE aa=3; -- ok
+ DELETE FROM rw_view2 WHERE aa=4; -- not allowed
+ ERROR:  permission denied for relation base_tbl
+ SELECT * FROM base_tbl;
+  a |   b   | c 
+ ---+-------+---
+  4 | Row 4 | 4
+  5 | Row 5 | 5
+ (2 rows)
+ 
+ RESET SESSION AUTHORIZATION;
+ DROP VIEW rw_view1, rw_view2;
+ DROP TABLE base_tbl;
+ DROP USER view_user1;
+ DROP USER view_user2;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
new file mode 100644
index ac29194..e25031e
*** a/src/test/regress/parallel_schedule
--- b/src/test/regress/parallel_schedule
*************** test: create_index create_view
*** 59,65 ****
  # ----------
  # Another group of parallel tests
  # ----------
! test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists
  
  # ----------
  # sanity_check does a vacuum, affecting the sort order of SELECT *
--- 59,65 ----
  # ----------
  # Another group of parallel tests
  # ----------
! test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views
  
  # ----------
  # sanity_check does a vacuum, affecting the sort order of SELECT *
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
new file mode 100644
index 8576a7f..f84ba64
*** a/src/test/regress/serial_schedule
--- b/src/test/regress/serial_schedule
*************** test: create_table_like
*** 67,72 ****
--- 67,73 ----
  test: typed_table
  test: vacuum
  test: drop_if_exists
+ test: updatable_views
  test: sanity_check
  test: errors
  test: select
diff --git a/src/test/regress/sql/triggers.sql b/src/test/regress/sql/triggers.sql
new file mode 100644
index f88cb81..ec579ec
*** a/src/test/regress/sql/triggers.sql
--- b/src/test/regress/sql/triggers.sql
*************** DROP TABLE min_updates_test_oids;
*** 611,623 ****
  
  CREATE VIEW main_view AS SELECT a, b FROM main_table;
  
- -- Updates should fail without rules or triggers
- INSERT INTO main_view VALUES (1,2);
- UPDATE main_view SET b = 20 WHERE a = 50;
- DELETE FROM main_view WHERE a = 50;
- -- Should fail even when there are no matching rows
- DELETE FROM main_view WHERE a = 51;
- 
  -- VIEW trigger function
  CREATE OR REPLACE FUNCTION view_trigger() RETURNS trigger
  LANGUAGE plpgsql AS $$
--- 611,616 ----
diff --git a/src/test/regress/sql/updatable_views.sql b/src/test/regress/sql/updatable_views.sql
new file mode 100644
index ...8d2b8d7
*** a/src/test/regress/sql/updatable_views.sql
--- b/src/test/regress/sql/updatable_views.sql
***************
*** 0 ****
--- 1,335 ----
+ --
+ -- UPDATABLE VIEWS
+ --
+ 
+ CREATE TABLE base_tbl (a int PRIMARY KEY, b text DEFAULT 'Unspecified');
+ INSERT INTO base_tbl VALUES (1, 'Row 1');
+ INSERT INTO base_tbl VALUES (2, 'Row 2');
+ 
+ -- non-updatable views
+ CREATE VIEW ro_view1 AS SELECT DISTINCT a, b FROM base_tbl; -- DISTINCT not supported
+ CREATE VIEW ro_view2 AS SELECT a, b FROM base_tbl GROUP BY a, b; -- GROUP BY not supported
+ CREATE VIEW ro_view3 AS SELECT 1 FROM base_tbl HAVING max(a) > 0; -- HAVING not supported
+ CREATE VIEW ro_view4 AS SELECT count(*) FROM base_tbl; -- Aggregate functions not supported
+ CREATE VIEW ro_view5 AS SELECT a, rank() OVER() FROM base_tbl; -- Window functions not supported
+ CREATE VIEW ro_view6 AS SELECT a, b FROM base_tbl UNION SELECT -a, b FROM base_tbl; -- Set ops not supported
+ CREATE VIEW ro_view7 AS WITH t AS (SELECT a, b FROM base_tbl) SELECT * FROM t; -- WITH [RECURSIVE] not supported
+ CREATE VIEW ro_view8 AS SELECT a, b FROM base_tbl ORDER BY a OFFSET 1; -- OFFSET not supported
+ CREATE VIEW ro_view9 AS SELECT a, b FROM base_tbl ORDER BY a LIMIT 1; -- LIMIT not supported
+ CREATE VIEW ro_view10 AS SELECT 1 AS a; -- No base relations
+ CREATE VIEW ro_view11 AS SELECT b1.a, b2.b FROM base_tbl b1, base_tbl b2; -- Multiple base relations
+ CREATE VIEW ro_view12 AS SELECT * FROM generate_series(1, 10) AS g(a); -- SRF in rangetable
+ CREATE VIEW ro_view13 AS SELECT a, b FROM (SELECT * FROM base_tbl) AS t; -- Subselect in rangetable
+ CREATE VIEW ro_view14 AS SELECT ctid FROM base_tbl; -- System columns not supported
+ CREATE VIEW ro_view15 AS SELECT a, upper(b) FROM base_tbl; -- Expression/function in targetlist
+ CREATE VIEW ro_view16 AS SELECT a, b, a AS aa FROM base_tbl; -- Repeated column
+ CREATE VIEW ro_view17 AS SELECT * FROM ro_view1; -- Base relation not updatable
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'ro_view%'
+  ORDER BY table_name;
+ 
+ DELETE FROM ro_view1;
+ DELETE FROM ro_view2;
+ DELETE FROM ro_view3;
+ DELETE FROM ro_view4;
+ DELETE FROM ro_view5;
+ DELETE FROM ro_view6;
+ UPDATE ro_view7 SET a=a+1;
+ UPDATE ro_view8 SET a=a+1;
+ UPDATE ro_view9 SET a=a+1;
+ UPDATE ro_view10 SET a=a+1;
+ UPDATE ro_view11 SET a=a+1;
+ UPDATE ro_view12 SET a=a+1;
+ INSERT INTO ro_view13 VALUES (3, 'Row 3');
+ INSERT INTO ro_view14 VALUES (null);
+ INSERT INTO ro_view15 VALUES (3, 'ROW 3');
+ INSERT INTO ro_view16 VALUES (3, 'Row 3', 3);
+ INSERT INTO ro_view17 VALUES (3, 'ROW 3');
+ 
+ DROP VIEW ro_view1, ro_view2, ro_view3, ro_view4, ro_view5,
+           ro_view6, ro_view7, ro_view8, ro_view9, ro_view10,
+           ro_view11, ro_view12, ro_view13, ro_view14, ro_view15,
+           ro_view16, ro_view17;
+ 
+ -- simple updatable view
+ CREATE VIEW rw_view1 AS SELECT * FROM base_tbl;
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view1';
+ 
+ INSERT INTO rw_view1 VALUES (3, 'Row 3');
+ INSERT INTO rw_view1 (a) VALUES (4);
+ UPDATE rw_view1 SET a=0 WHERE a=1;
+ DELETE FROM rw_view1 WHERE b='Row 2';
+ SELECT * FROM base_tbl;
+ 
+ EXPLAIN (costs off) UPDATE rw_view1 SET a=1 WHERE a=0;
+ EXPLAIN (costs off) DELETE FROM rw_view1 WHERE a=0;
+ 
+ -- view on top of view hiding private data
+ INSERT INTO base_tbl VALUES (-1, 'Private data');
+ CREATE VIEW rw_view2 AS SELECT * FROM rw_view1 WHERE b !~* 'private';
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view2';
+ 
+ SELECT * FROM base_tbl;
+ SELECT * FROM rw_view2;
+ 
+ INSERT INTO rw_view2 VALUES (5, 'Row 5');
+ INSERT INTO rw_view2 (a) VALUES (6);
+ SELECT * FROM rw_view2;
+ UPDATE rw_view2 SET b='Row 6' WHERE a=6;
+ DELETE FROM rw_view2 WHERE a=5;
+ SELECT * FROM rw_view2;
+ 
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=1 WHERE a=0;
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE a=0;
+ 
+ -- snoop on private value
+ CREATE FUNCTION snoop(a int, b text)
+ RETURNS boolean AS
+ $$
+ BEGIN
+   RAISE NOTICE 'a=%, b=%', a, b;
+   RETURN true;
+ END;
+ $$
+ LANGUAGE plpgsql COST 0.000001;
+ 
+ SELECT * FROM rw_view2 WHERE snoop(a,b);
+ UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ 
+ EXPLAIN (costs off) SELECT * FROM rw_view2 WHERE snoop(a,b);
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ 
+ -- security barrier view prevents snooping
+ ALTER VIEW rw_view2 SET (security_barrier = true);
+ 
+ SELECT * FROM rw_view2 WHERE snoop(a,b);
+ UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ 
+ EXPLAIN (costs off) SELECT * FROM rw_view2 WHERE snoop(a,b);
+ EXPLAIN (costs off) UPDATE rw_view2 SET a=a WHERE snoop(a,b);
+ EXPLAIN (costs off) DELETE FROM rw_view2 WHERE NOT snoop(a,b);
+ 
+ -- security barrier view on top of security barrier view
+ CREATE VIEW rw_view3 AS SELECT * FROM rw_view2 WHERE snoop(a,b);
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name = 'rw_view3';
+ 
+ SELECT * FROM rw_view3;
+ UPDATE rw_view3 SET a=a WHERE a=5;
+ DELETE FROM rw_view3 WHERE a=5;
+ 
+ EXPLAIN (costs off) SELECT * FROM rw_view3;
+ EXPLAIN (costs off) UPDATE rw_view3 SET a=a WHERE a=5;
+ EXPLAIN (costs off) DELETE FROM rw_view3 WHERE a=5;
+ 
+ DROP VIEW rw_view1, rw_view2, rw_view3;
+ 
+ -- view on top of view with rules
+ CREATE VIEW rw_view1 AS SELECT * FROM base_tbl OFFSET 0; -- not updatable without rules/triggers
+ CREATE VIEW rw_view2 AS SELECT * FROM rw_view1;
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE RULE rw_view1_ins_rule AS ON INSERT TO rw_view1
+   DO INSTEAD INSERT INTO base_tbl VALUES (NEW.a, NEW.b) RETURNING *;
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE RULE rw_view1_upd_rule AS ON UPDATE TO rw_view1
+   DO INSTEAD UPDATE base_tbl SET b=NEW.b WHERE a=OLD.a RETURNING NEW.*;
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE RULE rw_view1_del_rule AS ON DELETE TO rw_view1
+   DO INSTEAD DELETE FROM base_tbl WHERE a=OLD.a RETURNING OLD.*;
+ 
+ SELECT table_name, is_updatable, is_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ SELECT * FROM rw_view2;
+ INSERT INTO rw_view2 VALUES (7, 'Row 7') RETURNING *;
+ UPDATE rw_view2 SET b='Row seven' WHERE a=7 RETURNING *;
+ SELECT * FROM rw_view2;
+ DELETE FROM rw_view2 WHERE a=7 RETURNING *;
+ 
+ -- view on top of view with triggers
+ DROP RULE rw_view1_ins_rule ON rw_view1;
+ DROP RULE rw_view1_upd_rule ON rw_view1;
+ DROP RULE rw_view1_del_rule ON rw_view1;
+ 
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE FUNCTION rw_view1_trig_fn()
+ RETURNS trigger AS
+ $$
+ BEGIN
+   IF TG_OP = 'INSERT' THEN
+     INSERT INTO base_tbl VALUES (NEW.a, NEW.b);
+     RETURN NEW;
+   ELSIF TG_OP = 'UPDATE' THEN
+     UPDATE base_tbl SET b=NEW.b WHERE a=OLD.a;
+     RETURN NEW;
+   ELSIF TG_OP = 'DELETE' THEN
+     DELETE FROM base_tbl WHERE a=OLD.a;
+     RETURN OLD;
+   END IF;
+ END;
+ $$
+ LANGUAGE plpgsql;
+ 
+ CREATE TRIGGER rw_view1_ins_trig INSTEAD OF INSERT ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ 
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE TRIGGER rw_view1_upd_trig INSTEAD OF UPDATE ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ 
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ CREATE TRIGGER rw_view1_del_trig INSTEAD OF DELETE ON rw_view1
+   FOR EACH ROW EXECUTE PROCEDURE rw_view1_trig_fn();
+ 
+ SELECT table_name, is_updatable, is_insertable_into,
+        is_trigger_updatable, is_trigger_deletable,
+        is_trigger_insertable_into
+   FROM information_schema.views
+  WHERE table_name LIKE 'rw_view%'
+  ORDER BY table_name;
+ 
+ SELECT * FROM rw_view2;
+ INSERT INTO rw_view2 VALUES (7, 'Row 7') RETURNING *;
+ UPDATE rw_view2 SET b='Row seven' WHERE a=7 RETURNING *;
+ SELECT * FROM rw_view2;
+ DELETE FROM rw_view2 WHERE a=7 RETURNING *;
+ 
+ DROP VIEW rw_view1, rw_view2;
+ 
+ -- test whole row from view
+ CREATE VIEW rw_view1 AS SELECT b AS bb, a AS aa FROM base_tbl;
+ 
+ CREATE FUNCTION rw_view1_aa(x rw_view1)
+   RETURNS int AS $$ SELECT x.aa $$ LANGUAGE sql;
+ 
+ UPDATE rw_view1 v SET bb='Updated row 6' WHERE rw_view1_aa(v)=6
+   RETURNING rw_view1_aa(v), v.bb;
+ SELECT * FROM base_tbl;
+ 
+ EXPLAIN (costs off)
+ UPDATE rw_view1 v SET bb='Updated row 6' WHERE rw_view1_aa(v)=6
+   RETURNING rw_view1_aa(v), v.bb;
+ 
+ DROP FUNCTION rw_view1_aa(rw_view1);
+ DROP VIEW rw_view1;
+ DROP TABLE base_tbl;
+ 
+ -- permissions checks
+ CREATE USER view_user1;
+ CREATE USER view_user2;
+ 
+ SET SESSION AUTHORIZATION view_user1;
+ CREATE TABLE base_tbl(a int, b text, c float);
+ INSERT INTO base_tbl VALUES (1, 'Row 1', 1.0);
+ CREATE VIEW rw_view1 AS SELECT b AS bb, c AS cc, a AS aa FROM base_tbl;
+ INSERT INTO rw_view1 VALUES ('Row 2', 2.0, 2);
+ 
+ GRANT SELECT ON base_tbl TO view_user2;
+ GRANT SELECT ON rw_view1 TO view_user2;
+ GRANT UPDATE (a,c) ON base_tbl TO view_user2;
+ GRANT UPDATE (bb,cc) ON rw_view1 TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ 
+ SET SESSION AUTHORIZATION view_user2;
+ CREATE VIEW rw_view2 AS SELECT b AS bb, c AS cc, a AS aa FROM base_tbl;
+ SELECT * FROM base_tbl; -- ok
+ SELECT * FROM rw_view1; -- ok
+ SELECT * FROM rw_view2; -- ok
+ 
+ INSERT INTO base_tbl VALUES (3, 'Row 3', 3.0); -- not allowed
+ INSERT INTO rw_view1 VALUES ('Row 3', 3.0, 3); -- not allowed
+ INSERT INTO rw_view2 VALUES ('Row 3', 3.0, 3); -- not allowed
+ 
+ UPDATE base_tbl SET a=a, c=c; -- ok
+ UPDATE base_tbl SET b=b; -- not allowed
+ UPDATE rw_view1 SET bb=bb, cc=cc; -- ok
+ UPDATE rw_view1 SET aa=aa; -- not allowed
+ UPDATE rw_view2 SET aa=aa, cc=cc; -- ok
+ UPDATE rw_view2 SET bb=bb; -- not allowed
+ 
+ DELETE FROM base_tbl; -- not allowed
+ DELETE FROM rw_view1; -- not allowed
+ DELETE FROM rw_view2; -- not allowed
+ RESET SESSION AUTHORIZATION;
+ 
+ SET SESSION AUTHORIZATION view_user1;
+ GRANT INSERT, DELETE ON base_tbl TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ 
+ SET SESSION AUTHORIZATION view_user2;
+ INSERT INTO base_tbl VALUES (3, 'Row 3', 3.0); -- ok
+ INSERT INTO rw_view1 VALUES ('Row 4', 4.0, 4); -- not allowed
+ INSERT INTO rw_view2 VALUES ('Row 4', 4.0, 4); -- ok
+ DELETE FROM base_tbl WHERE a=1; -- ok
+ DELETE FROM rw_view1 WHERE aa=2; -- not allowed
+ DELETE FROM rw_view2 WHERE aa=2; -- ok
+ SELECT * FROM base_tbl;
+ RESET SESSION AUTHORIZATION;
+ 
+ SET SESSION AUTHORIZATION view_user1;
+ REVOKE INSERT, DELETE ON base_tbl FROM view_user2;
+ GRANT INSERT, DELETE ON rw_view1 TO view_user2;
+ RESET SESSION AUTHORIZATION;
+ 
+ SET SESSION AUTHORIZATION view_user2;
+ INSERT INTO base_tbl VALUES (5, 'Row 5', 5.0); -- not allowed
+ INSERT INTO rw_view1 VALUES ('Row 5', 5.0, 5); -- ok
+ INSERT INTO rw_view2 VALUES ('Row 6', 6.0, 6); -- not allowed
+ DELETE FROM base_tbl WHERE a=3; -- not allowed
+ DELETE FROM rw_view1 WHERE aa=3; -- ok
+ DELETE FROM rw_view2 WHERE aa=4; -- not allowed
+ SELECT * FROM base_tbl;
+ RESET SESSION AUTHORIZATION;
+ 
+ DROP VIEW rw_view1, rw_view2;
+ DROP TABLE base_tbl;
+ DROP USER view_user1;
+ DROP USER view_user2;