MERGE SQL Command following SQL:2016

MERGE performs actions that modify rows in the target table
using a source table or query. MERGE provides a single SQL
statement that can conditionally INSERT/UPDATE/DELETE rows
a task that would other require multiple PL statements.
e.g.

MERGE INTO target AS t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND t.balance > s.delta THEN
  UPDATE SET balance = t.balance - s.delta
WHEN MATCHED THEN
  DELETE
WHEN NOT MATCHED AND s.delta > 0 THEN
  INSERT VALUES (s.sid, s.delta)
WHEN NOT MATCHED THEN
  DO NOTHING;

MERGE works with regular and partitioned tables, including
column and row security enforcement, as well as support for
row, statement and transition triggers.

MERGE is optimized for OLTP and is parameterizable, though
also useful for large scale ETL/ELT. MERGE is not intended
to be used in preference to existing single SQL commands
for INSERT, UPDATE or DELETE since there is some overhead.
MERGE can be used statically from PL/pgSQL.

MERGE does not yet support inheritance, write rules,
RETURNING clauses, updatable views or foreign tables.
MERGE follows SQL Standard per the most recent SQL:2016.

Includes full tests and documentation, including full
isolation tests to demonstrate the concurrent behavior.

This version written from scratch in 2017 by Simon Riggs,
using docs and tests originally written in 2009. Later work
from Pavan Deolasee has been both complex and deep, leaving
the lead author credit now in his hands.
Extensive discussion of concurrency from Peter Geoghegan,
with thanks for the time and effort contributed.

Various issues reported via sqlsmith by Andreas Seltenreich

Authors: Pavan Deolasee, Simon Riggs
Reviewers: Peter Geoghegan, Amit Langote, Tomas Vondra, Simon Riggs

Discussion:
https://postgr.es/m/CANP8+jKitBSrB7oTgT9CY2i1ObfOt36z0XMraQc+Xrz8QB0nXA@mail.gmail.com
https://postgr.es/m/CAH2-WzkJdBuxj9PO=2QaO9-3h3xGbQPZ34kJH=HukRekwM-GZg@mail.gmail.com

1 files changed, 660 insertions, 0 deletions

diff --git a/src/backend/parser/parse_merge.c b/src/backend/parser/parse_merge.c
new file mode 100644
index 00000000000..e073d93daf6
--- /dev/null
+++ b/src/backend/parser/parse_merge.c
@@ -0,0 +1,660 @@
+/*-------------------------------------------------------------------------
+ *
+ * parse_merge.c
+ *	  handle merge-statement in parser
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/parser/parse_merge.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "miscadmin.h"
+
+#include "access/sysattr.h"
+#include "nodes/makefuncs.h"
+#include "parser/analyze.h"
+#include "parser/parse_collate.h"
+#include "parser/parsetree.h"
+#include "parser/parser.h"
+#include "parser/parse_clause.h"
+#include "parser/parse_merge.h"
+#include "parser/parse_relation.h"
+#include "parser/parse_target.h"
+#include "utils/rel.h"
+#include "utils/relcache.h"
+
+static int transformMergeJoinClause(ParseState *pstate, Node *merge,
+						List **mergeSourceTargetList);
+static void setNamespaceForMergeAction(ParseState *pstate,
+						MergeAction *action);
+static void setNamespaceVisibilityForRTE(List *namespace, RangeTblEntry *rte,
+							 bool rel_visible,
+							 bool cols_visible);
+static List *expandSourceTL(ParseState *pstate, RangeTblEntry *rte,
+							int rtindex);
+
+/*
+ *	Special handling for MERGE statement is required because we assemble
+ *	the query manually. This is similar to setTargetTable() followed
+ * 	by transformFromClause() but with a few less steps.
+ *
+ *	Process the FROM clause and add items to the query's range table,
+ *	joinlist, and namespace.
+ *
+ *	A special targetlist comprising of the columns from the right-subtree of
+ *	the join is populated and returned. Note that when the JoinExpr is
+ *	setup by transformMergeStmt, the left subtree has the target result
+ *	relation and the right subtree has the source relation.
+ *
+ *	Returns the rangetable index of the target relation.
+ */
+static int
+transformMergeJoinClause(ParseState *pstate, Node *merge,
+						 List **mergeSourceTargetList)
+{
+	RangeTblEntry *rte,
+			   *rt_rte;
+	List	   *namespace;
+	int			rtindex,
+				rt_rtindex;
+	Node	   *n;
+	int			mergeTarget_relation = list_length(pstate->p_rtable) + 1;
+	Var		   *var;
+	TargetEntry *te;
+
+	n = transformFromClauseItem(pstate, merge,
+								&rte,
+								&rtindex,
+								&rt_rte,
+								&rt_rtindex,
+								&namespace);
+
+	pstate->p_joinlist = list_make1(n);
+
+	/*
+	 * We created an internal join between the target and the source relation
+	 * to carry out the MERGE actions. Normally such an unaliased join hides
+	 * the joining relations, unless the column references are qualified.
+	 * Also, any unqualified column references are resolved to the Join RTE, if
+	 * there is a matching entry in the targetlist. But the way MERGE
+	 * execution is later setup, we expect all column references to resolve to
+	 * either the source or the target relation. Hence we must not add the
+	 * Join RTE to the namespace.
+	 *
+	 * The last entry must be for the top-level Join RTE. We don't want to
+	 * resolve any references to the Join RTE. So discard that.
+	 *
+	 * We also do not want to resolve any references from the leftside of the
+	 * Join since that corresponds to the target relation. References to the
+	 * columns of the target relation must be resolved from the result
+	 * relation and not the one that is used in the join. So the
+	 * mergeTarget_relation is marked invisible to both qualified as well as
+	 * unqualified references.
+	 */
+	Assert(list_length(namespace) > 1);
+	namespace = list_truncate(namespace, list_length(namespace) - 1);
+	pstate->p_namespace = list_concat(pstate->p_namespace, namespace);
+
+	setNamespaceVisibilityForRTE(pstate->p_namespace,
+								 rt_fetch(mergeTarget_relation, pstate->p_rtable), false, false);
+
+	/*
+	 * Expand the right relation and add its columns to the
+	 * mergeSourceTargetList. Note that the right relation can either be a
+	 * plain relation or a subquery or anything that can have a
+	 * RangeTableEntry.
+	 */
+	*mergeSourceTargetList = expandSourceTL(pstate, rt_rte, rt_rtindex);
+
+	/*
+	 * Add a whole-row-Var entry to support references to "source.*".
+	 */
+	var = makeWholeRowVar(rt_rte, rt_rtindex, 0, false);
+	te = makeTargetEntry((Expr *) var, list_length(*mergeSourceTargetList) + 1,
+						 NULL, true);
+	*mergeSourceTargetList = lappend(*mergeSourceTargetList, te);
+
+	return mergeTarget_relation;
+}
+
+/*
+ * Make appropriate changes to the namespace visibility while transforming
+ * individual action's quals and targetlist expressions. In particular, for
+ * INSERT actions we must only see the source relation (since INSERT action is
+ * invoked for NOT MATCHED tuples and hence there is no target tuple to deal
+ * with). On the other hand, UPDATE and DELETE actions can see both source and
+ * target relations.
+ *
+ * Also, since the internal Join node can hide the source and target
+ * relations, we must explicitly make the respective relation as visible so
+ * that columns can be referenced unqualified from these relations.
+ */
+static void
+setNamespaceForMergeAction(ParseState *pstate, MergeAction *action)
+{
+	RangeTblEntry *targetRelRTE,
+			   *sourceRelRTE;
+
+	/* Assume target relation is at index 1 */
+	targetRelRTE = rt_fetch(1, pstate->p_rtable);
+
+	/*
+	 * Assume that the top-level join RTE is at the end. The source relation
+	 * is just before that.
+	 */
+	sourceRelRTE = rt_fetch(list_length(pstate->p_rtable) - 1, pstate->p_rtable);
+
+	switch (action->commandType)
+	{
+		case CMD_INSERT:
+
+			/*
+			 * Inserts can't see target relation, but they can see source
+			 * relation.
+			 */
+			setNamespaceVisibilityForRTE(pstate->p_namespace,
+										 targetRelRTE, false, false);
+			setNamespaceVisibilityForRTE(pstate->p_namespace,
+										 sourceRelRTE, true, true);
+			break;
+
+		case CMD_UPDATE:
+		case CMD_DELETE:
+
+			/*
+			 * Updates and deletes can see both target and source relations.
+			 */
+			setNamespaceVisibilityForRTE(pstate->p_namespace,
+										 targetRelRTE, true, true);
+			setNamespaceVisibilityForRTE(pstate->p_namespace,
+										 sourceRelRTE, true, true);
+			break;
+
+		case CMD_NOTHING:
+			break;
+		default:
+			elog(ERROR, "unknown action in MERGE WHEN clause");
+	}
+}
+
+/*
+ * transformMergeStmt -
+ *	  transforms a MERGE statement
+ */
+Query *
+transformMergeStmt(ParseState *pstate, MergeStmt *stmt)
+{
+	Query		   *qry = makeNode(Query);
+	ListCell	   *l;
+	AclMode			targetPerms = ACL_NO_RIGHTS;
+	bool			is_terminal[2];
+	JoinExpr	   *joinexpr;
+	RangeTblEntry  *resultRelRTE, *mergeRelRTE;
+
+	/* There can't be any outer WITH to worry about */
+	Assert(pstate->p_ctenamespace == NIL);
+
+	qry->commandType = CMD_MERGE;
+
+	/*
+	 * Check WHEN clauses for permissions and sanity
+	 */
+	is_terminal[0] = false;
+	is_terminal[1] = false;
+	foreach(l, stmt->mergeActionList)
+	{
+		MergeAction *action = (MergeAction *) lfirst(l);
+		uint		when_type = (action->matched ? 0 : 1);
+
+		/*
+		 * Collect action types so we can check Target permissions
+		 */
+		switch (action->commandType)
+		{
+			case CMD_INSERT:
+				{
+					InsertStmt *istmt = (InsertStmt *) action->stmt;
+					SelectStmt *selectStmt = (SelectStmt *) istmt->selectStmt;
+
+					/*
+					 * The grammar allows attaching ORDER BY, LIMIT, FOR
+					 * UPDATE, or WITH to a VALUES clause and also multiple
+					 * VALUES clauses. If we have any of those, ERROR.
+					 */
+					if (selectStmt && (selectStmt->valuesLists == NIL ||
+									   selectStmt->sortClause != NIL ||
+									   selectStmt->limitOffset != NULL ||
+									   selectStmt->limitCount != NULL ||
+									   selectStmt->lockingClause != NIL ||
+									   selectStmt->withClause != NULL))
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("SELECT not allowed in MERGE INSERT statement")));
+
+					if (selectStmt && list_length(selectStmt->valuesLists) > 1)
+						ereport(ERROR,
+								(errcode(ERRCODE_SYNTAX_ERROR),
+								 errmsg("Multiple VALUES clauses not allowed in MERGE INSERT statement")));
+
+					targetPerms |= ACL_INSERT;
+				}
+				break;
+			case CMD_UPDATE:
+				targetPerms |= ACL_UPDATE;
+				break;
+			case CMD_DELETE:
+				targetPerms |= ACL_DELETE;
+				break;
+			case CMD_NOTHING:
+				break;
+			default:
+				elog(ERROR, "unknown action in MERGE WHEN clause");
+		}
+
+		/*
+		 * Check for unreachable WHEN clauses
+		 */
+		if (action->condition == NULL)
+			is_terminal[when_type] = true;
+		else if (is_terminal[when_type])
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("unreachable WHEN clause specified after unconditional WHEN clause")));
+	}
+
+	/*
+	 * Construct a query of the form
+	 * 	SELECT relation.ctid	--junk attribute
+	 *		  ,relation.tableoid	--junk attribute
+	 * 		  ,source_relation.<somecols>
+	 * 		  ,relation.<somecols>
+	 *  FROM relation RIGHT JOIN source_relation
+	 *  ON  join_condition; -- no WHERE clause - all conditions are applied in
+	 * executor
+	 *
+	 * stmt->relation is the target relation, given as a RangeVar
+	 * stmt->source_relation is a RangeVar or subquery
+	 *
+	 * We specify the join as a RIGHT JOIN as a simple way of forcing the
+	 * first (larg) RTE to refer to the target table.
+	 *
+	 * The MERGE query's join can be tuned in some cases, see below for these
+	 * special case tweaks.
+	 *
+	 * We set QSRC_PARSER to show query constructed in parse analysis
+	 *
+	 * Note that we have only one Query for a MERGE statement and the planner
+	 * is called only once. That query is executed once to produce our stream
+	 * of candidate change rows, so the query must contain all of the columns
+	 * required by each of the targetlist or conditions for each action.
+	 *
+	 * As top-level statements INSERT, UPDATE and DELETE have a Query, whereas
+	 * with MERGE the individual actions do not require separate planning,
+	 * only different handling in the executor. See nodeModifyTable handling
+	 * of commandType CMD_MERGE.
+	 *
+	 * A sub-query can include the Target, but otherwise the sub-query cannot
+	 * reference the outermost Target table at all.
+	 */
+	qry->querySource = QSRC_PARSER;
+
+	/*
+	 * Setup the target table. Unlike regular UPDATE/DELETE, we don't expand
+	 * inheritance for the target relation in case of MERGE.
+	 *
+	 * This special arrangement is required for handling partitioned tables
+	 * because we perform an JOIN between the target and the source relation to
+	 * identify the matching and not-matching rows. If we take the usual path
+	 * of expanding the target table's inheritance and create one subplan per
+	 * partition, then we we won't be able to correctly identify the matching
+	 * and not-matching rows since for a given source row, there may not be a
+	 * matching row in one partition, but it may exists in some other
+	 * partition. So we must first append all the qualifying rows from all the
+	 * partitions and then do the matching.
+	 *
+	 * Once a target row is returned by the underlying join, we find the
+	 * correct partition and setup required state to carry out UPDATE/DELETE.
+	 * All of this happens during execution.
+	 */
+	qry->resultRelation = setTargetTable(pstate, stmt->relation,
+										 false,	/* do not expand inheritance */
+										 true, targetPerms);
+
+	/*
+	 * Create a JOIN between the target and the source relation.
+	 */
+	joinexpr = makeNode(JoinExpr);
+	joinexpr->isNatural = false;
+	joinexpr->alias = NULL;
+	joinexpr->usingClause = NIL;
+	joinexpr->quals = stmt->join_condition;
+	joinexpr->larg = (Node *) stmt->relation;
+	joinexpr->rarg = (Node *) stmt->source_relation;
+
+	/*
+	 * Simplify the MERGE query as much as possible
+	 *
+	 * These seem like things that could go into Optimizer, but they are
+	 * semantic simplifications rather than optimizations, per se.
+	 *
+	 * If there are no INSERT actions we won't be using the non-matching
+	 * candidate rows for anything, so no need for an outer join. We do still
+	 * need an inner join for UPDATE and DELETE actions.
+	 */
+	if (targetPerms & ACL_INSERT)
+		joinexpr->jointype = JOIN_RIGHT;
+	else
+		joinexpr->jointype = JOIN_INNER;
+
+	/*
+	 * We use a special purpose transformation here because the normal
+	 * routines don't quite work right for the MERGE case.
+	 *
+	 * A special mergeSourceTargetList is setup by transformMergeJoinClause().
+	 * It refers to all the attributes provided by the source relation. This
+	 * is later used by set_plan_refs() to fix the UPDATE/INSERT target lists
+	 * to so that they can correctly fetch the attributes from the source
+	 * relation.
+	 *
+	 * The target relation when used in the underlying join, gets a new RTE
+	 * with rte->inh set to true. We remember this RTE (and later pass on to
+	 * the planner and executor) for two main reasons:
+	 *
+	 * 1. If we ever need to run EvalPlanQual while performing MERGE, we must
+	 * make the modified tuple available to the underlying join query, which is
+	 * using a different RTE from the resultRelation RTE.
+	 *
+	 * 2. rewriteTargetListMerge() requires the RTE of the underlying join in
+	 * order to add junk CTID and TABLEOID attributes.
+	 */
+	qry->mergeTarget_relation = transformMergeJoinClause(pstate, (Node *) joinexpr,
+														 &qry->mergeSourceTargetList);
+
+	/*
+	 * The target table referenced in the MERGE is looked up twice; once while
+	 * setting it up as the result relation and again when it's used in the
+	 * underlying the join query. In some rare situations, it may happen that
+	 * these lookups return different results, for example, if a new relation
+	 * with the same name gets created in a schema which is ahead in the
+	 * search_path, in between the two lookups.
+	 *
+	 * It's a very narrow case, but nevertheless we guard against it by simply
+	 * checking if the OIDs returned by the two lookups is the same. If not, we
+	 * just throw an error.
+	 */
+	Assert(qry->resultRelation > 0);
+	Assert(qry->mergeTarget_relation > 0);
+
+	/* Fetch both the RTEs */
+	resultRelRTE = rt_fetch(qry->resultRelation, pstate->p_rtable);
+	mergeRelRTE = rt_fetch(qry->mergeTarget_relation, pstate->p_rtable);
+
+	if (resultRelRTE->relid != mergeRelRTE->relid)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("relation referenced by MERGE statement has changed")));
+
+	/*
+	 * This query should just provide the source relation columns. Later, in
+	 * preprocess_targetlist(), we shall also add "ctid" attribute of the
+	 * target relation to ensure that the target tuple can be fetched
+	 * correctly.
+	 */
+	qry->targetList = qry->mergeSourceTargetList;
+
+	/* qry has no WHERE clause so absent quals are shown as NULL */
+	qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);
+	qry->rtable = pstate->p_rtable;
+
+	/*
+	 * XXX MERGE is unsupported in various cases
+	 */
+	if (!(pstate->p_target_relation->rd_rel->relkind == RELKIND_RELATION ||
+		  pstate->p_target_relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("MERGE is not supported for this relation type")));
+
+	if (pstate->p_target_relation->rd_rel->relkind != RELKIND_PARTITIONED_TABLE &&
+		pstate->p_target_relation->rd_rel->relhassubclass)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("MERGE is not supported for relations with inheritance")));
+
+	if (pstate->p_target_relation->rd_rel->relhasrules)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("MERGE is not supported for relations with rules")));
+
+	/*
+	 * We now have a good query shape, so now look at the when conditions and
+	 * action targetlists.
+	 *
+	 * Overall, the MERGE Query's targetlist is NIL.
+	 *
+	 * Each individual action has its own targetlist that needs separate
+	 * transformation. These transforms don't do anything to the overall
+	 * targetlist, since that is only used for resjunk columns.
+	 *
+	 * We can reference any column in Target or Source, which is OK because
+	 * both of those already have RTEs. There is nothing like the EXCLUDED
+	 * pseudo-relation for INSERT ON CONFLICT.
+	 */
+	foreach(l, stmt->mergeActionList)
+	{
+		MergeAction *action = (MergeAction *) lfirst(l);
+
+		/*
+		 * Set namespace for the specific action. This must be done before
+		 * analyzing the WHEN quals and the action targetlisst.
+		 */
+		setNamespaceForMergeAction(pstate, action);
+
+		/*
+		 * Transform the when condition.
+		 *
+		 * Note that these quals are NOT added to the join quals; instead they
+		 * are evaluated separately during execution to decide which of the
+		 * WHEN MATCHED or WHEN NOT MATCHED actions to execute.
+		 */
+		action->qual = transformWhereClause(pstate, action->condition,
+											EXPR_KIND_MERGE_WHEN_AND, "WHEN");
+
+		/*
+		 * Transform target lists for each INSERT and UPDATE action stmt
+		 */
+		switch (action->commandType)
+		{
+			case CMD_INSERT:
+				{
+					InsertStmt *istmt = (InsertStmt *) action->stmt;
+					SelectStmt *selectStmt = (SelectStmt *) istmt->selectStmt;
+					List	   *exprList = NIL;
+					ListCell   *lc;
+					RangeTblEntry *rte;
+					ListCell   *icols;
+					ListCell   *attnos;
+					List	   *icolumns;
+					List	   *attrnos;
+
+					pstate->p_is_insert = true;
+
+					icolumns = checkInsertTargets(pstate, istmt->cols, &attrnos);
+					Assert(list_length(icolumns) == list_length(attrnos));
+
+					/*
+					 * Handle INSERT much like in transformInsertStmt
+					 */
+					if (selectStmt == NULL)
+					{
+						/*
+						 * We have INSERT ... DEFAULT VALUES.  We can handle
+						 * this case by emitting an empty targetlist --- all
+						 * columns will be defaulted when the planner expands
+						 * the targetlist.
+						 */
+						exprList = NIL;
+					}
+					else
+					{
+						/*
+						 * Process INSERT ... VALUES with a single VALUES
+						 * sublist.  We treat this case separately for
+						 * efficiency.  The sublist is just computed directly
+						 * as the Query's targetlist, with no VALUES RTE.  So
+						 * it works just like a SELECT without any FROM.
+						 */
+						List	   *valuesLists = selectStmt->valuesLists;
+
+						Assert(list_length(valuesLists) == 1);
+						Assert(selectStmt->intoClause == NULL);
+
+						/*
+						 * Do basic expression transformation (same as a ROW()
+						 * expr, but allow SetToDefault at top level)
+						 */
+						exprList = transformExpressionList(pstate,
+														   (List *) linitial(valuesLists),
+														   EXPR_KIND_VALUES_SINGLE,
+														   true);
+
+						/* Prepare row for assignment to target table */
+						exprList = transformInsertRow(pstate, exprList,
+													  istmt->cols,
+													  icolumns, attrnos,
+													  false);
+					}
+
+					/*
+					 * Generate action's target list using the computed list
+					 * of expressions. Also, mark all the target columns as
+					 * needing insert permissions.
+					 */
+					rte = pstate->p_target_rangetblentry;
+					icols = list_head(icolumns);
+					attnos = list_head(attrnos);
+					foreach(lc, exprList)
+					{
+						Expr	   *expr = (Expr *) lfirst(lc);
+						ResTarget  *col;
+						AttrNumber	attr_num;
+						TargetEntry *tle;
+
+						col = lfirst_node(ResTarget, icols);
+						attr_num = (AttrNumber) lfirst_int(attnos);
+
+						tle = makeTargetEntry(expr,
+											  attr_num,
+											  col->name,
+											  false);
+						action->targetList = lappend(action->targetList, tle);
+
+						rte->insertedCols = bms_add_member(rte->insertedCols,
+														   attr_num - FirstLowInvalidHeapAttributeNumber);
+
+						icols = lnext(icols);
+						attnos = lnext(attnos);
+					}
+				}
+				break;
+			case CMD_UPDATE:
+				{
+					UpdateStmt *ustmt = (UpdateStmt *) action->stmt;
+
+					pstate->p_is_insert = false;
+					action->targetList = transformUpdateTargetList(pstate, ustmt->targetList);
+				}
+				break;
+			case CMD_DELETE:
+				break;
+
+			case CMD_NOTHING:
+				action->targetList = NIL;
+				break;
+			default:
+				elog(ERROR, "unknown action in MERGE WHEN clause");
+		}
+	}
+
+	qry->mergeActionList = stmt->mergeActionList;
+
+	/* XXX maybe later */
+	qry->returningList = NULL;
+
+	qry->hasTargetSRFs = false;
+	qry->hasSubLinks = pstate->p_hasSubLinks;
+
+	assign_query_collations(pstate, qry);
+
+	return qry;
+}
+
+static void
+setNamespaceVisibilityForRTE(List *namespace, RangeTblEntry *rte,
+							 bool rel_visible,
+							 bool cols_visible)
+{
+	ListCell   *lc;
+
+	foreach(lc, namespace)
+	{
+		ParseNamespaceItem *nsitem = (ParseNamespaceItem *) lfirst(lc);
+
+		if (nsitem->p_rte == rte)
+		{
+			nsitem->p_rel_visible = rel_visible;
+			nsitem->p_cols_visible = cols_visible;
+			break;
+		}
+	}
+
+}
+
+/*
+ * Expand the source relation to include all attributes of this RTE.
+ *
+ * This function is very similar to expandRelAttrs except that we don't mark
+ * columns for SELECT privileges. That will be decided later when we transform
+ * the action targetlists and the WHEN quals for actual references to the
+ * source relation.
+ */
+static List *
+expandSourceTL(ParseState *pstate, RangeTblEntry *rte, int rtindex)
+{
+	List	   *names,
+			   *vars;
+	ListCell   *name,
+			   *var;
+	List	   *te_list = NIL;
+
+	expandRTE(rte, rtindex, 0, -1, false, &names, &vars);
+
+	/*
+	 * Require read access to the table.
+	 */
+	rte->requiredPerms |= ACL_SELECT;
+
+	forboth(name, names, var, vars)
+	{
+		char	   *label = strVal(lfirst(name));
+		Var		   *varnode = (Var *) lfirst(var);
+		TargetEntry *te;
+
+		te = makeTargetEntry((Expr *) varnode,
+							 (AttrNumber) pstate->p_next_resno++,
+							 label,
+							 false);
+		te_list = lappend(te_list, te);
+	}
+
+	Assert(name == NULL && var == NULL);	/* lists not the same length? */
+
+	return te_list;
+}