Merge branch 'main' into m3hm3t/pg18_rc1_conf

configure

@@ -1,6 +1,6 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for Citus 13.2devel.
+# Generated by GNU Autoconf 2.69 for Citus 14.0devel.
 #
 #
 # Copyright (C) 1992-1996, 1998-2012 Free Software Foundation, Inc.
@@ -579,8 +579,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='Citus'
 PACKAGE_TARNAME='citus'
-PACKAGE_VERSION='13.2devel'
+PACKAGE_VERSION='14.0devel'
-PACKAGE_STRING='Citus 13.2devel'
+PACKAGE_STRING='Citus 14.0devel'
 PACKAGE_BUGREPORT=''
 PACKAGE_URL=''
 
@@ -1262,7 +1262,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures Citus 13.2devel to adapt to many kinds of systems.
+\`configure' configures Citus 14.0devel to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1324,7 +1324,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of Citus 13.2devel:";;
+     short | recursive ) echo "Configuration of Citus 14.0devel:";;
    esac
   cat <<\_ACEOF
 
@@ -1429,7 +1429,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-Citus configure 13.2devel
+Citus configure 14.0devel
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -1912,7 +1912,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by Citus $as_me 13.2devel, which was
+It was created by Citus $as_me 14.0devel, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -5393,7 +5393,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by Citus $as_me 13.2devel, which was
+This file was extended by Citus $as_me 14.0devel, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -5455,7 +5455,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-Citus config.status 13.2devel
+Citus config.status 14.0devel
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 

configure.ac

@@ -5,7 +5,7 @@
 # everyone needing autoconf installed, the resulting files are checked
 # into the SCM.
 
-AC_INIT([Citus], [13.2devel])
+AC_INIT([Citus], [14.0devel])
 AC_COPYRIGHT([Copyright (c) Citus Data, Inc.])
 
 # we'll need sed and awk for some of the version commands

src/backend/columnar/citus_columnar.control

@@ -1,6 +1,6 @@
 # Columnar extension
 comment = 'Citus Columnar extension'
-default_version = '13.2-1'
+default_version = '14.0-1'
 module_pathname = '$libdir/citus_columnar'
 relocatable = false
 schema = pg_catalog

src/backend/columnar/columnar_metadata.c

@@ -1267,7 +1267,21 @@ StripesForRelfilelocator(RelFileLocator relfilelocator)
 {
 	uint64 storageId = LookupStorageId(relfilelocator);
 
-	return ReadDataFileStripeList(storageId, GetTransactionSnapshot());
+	/*
+	 * PG18 requires snapshot to be active or registered before it's used
+	 * Without this, we hit
+	 * Assert(snapshot->regd_count > 0 || snapshot->active_count > 0);
+	 * when reading columnar stripes.
+	 * Relevant PG18 commit:
+	 * 8076c00592e40e8dbd1fce7a98b20d4bf075e4ba
+	 */
+	Snapshot snapshot = RegisterSnapshot(GetTransactionSnapshot());
+
+	List *readDataFileStripeList = ReadDataFileStripeList(storageId, snapshot);
+
+	UnregisterSnapshot(snapshot);
+
+	return readDataFileStripeList;
 }
 
 

src/backend/columnar/sql/citus_columnar--13.2-1--14.0-1.sql

@@ -0,0 +1,2 @@
+-- citus_columnar--13.2-1--14.0-1
+-- bump version to 14.0-1

src/backend/columnar/sql/downgrades/citus_columnar--14.0-1--13.2-1.sql

@@ -0,0 +1,2 @@
+-- citus_columnar--14.0-1--13.2-1
+-- downgrade version to 13.2-1

src/backend/distributed/README.md

@@ -797,14 +797,13 @@ WHERE l.user_id = o.user_id AND o.primary_key = 55;
 
 
 
-### Ref table LEFT JOIN distributed table JOINs via recursive planning
+### Outer joins between reference and distributed tables
 
-Very much like local-distributed table joins, Citus can't push down queries formatted as:
+In general, when the outer side of an outer join is a recurring tuple (e.g., reference table, intermediate results, or set returning functions), it is not safe to push down the join.
 ```sql
 "... ref_table LEFT JOIN distributed_table ..."
+"... distributed_table RIGHT JOIN ref_table ..."
 ```
-This is the case when the outer side is a recurring tuple (e.g., reference table, intermediate results, or set returning functions).
-
 In these situations, Citus recursively plans the "distributed" part of the join. Even though it may seem excessive to recursively plan a distributed table, remember that Citus pushes down the filters and projections. Functions involved here include `RequiredAttrNumbersForRelation()` and `ReplaceRTERelationWithRteSubquery()`.
 
 The core function handling this logic is `RecursivelyPlanRecurringTupleOuterJoinWalker()`. There are likely numerous optimizations possible (e.g., first pushing down an inner JOIN then an outer join), but these have not been implemented due to their complexity.
@@ -828,6 +827,45 @@ DEBUG:  Wrapping relation "orders_table" "o" to a subquery
 DEBUG:  generating subplan 45_1 for subquery SELECT order_id, status FROM public.orders_table o WHERE true
 ```
 
+As of Citus 13.2, under certain conditions, Citus can push down these types of LEFT and RIGHT outer joins by injecting constraints—derived from the shard intervals of distributed tables—into shard queries for the reference table. The eligibility rules for pushdown are defined in `CanPushdownRecurringOuterJoin()`, while the logic for computing and injecting the constraints is implemented in `UpdateWhereClauseToPushdownRecurringOuterJoin()`.
+
+#### Example Query
+
+In the example below, Citus pushes down the query by injecting interval constraints on the reference table. The injected constraints are visible in the EXPLAIN output.
+
+```sql
+SELECT pc.category_name, count(pt.product_id)
+FROM product_categories pc
+LEFT JOIN products_table pt ON pc.category_id = pt.product_id
+GROUP BY pc.category_name;
+```
+
+#### Debug Messages
+```
+DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  a push down safe left join with recurring left side
+```
+
+#### Explain Output
+```
+HashAggregate
+  Group Key: remote_scan.category_name
+  ->  Custom Scan (Citus Adaptive)
+        Task Count: 32
+        Tasks Shown: One of 32
+        ->  Task
+              Node: host=localhost port=9701 dbname=ebru
+              ->  HashAggregate
+                    Group Key: pc.category_name
+                    ->  Hash Right Join
+                          Hash Cond: (pt.product_id = pc.category_id)
+                          ->  Seq Scan on products_table_102072 pt
+                          ->  Hash
+                                ->  Seq Scan on product_categories_102106 pc
+                                      Filter: ((category_id IS NULL) OR ((btint4cmp('-2147483648'::integer, hashint8((category_id)::bigint)) < 0) AND (btint4cmp(hashint8((category_id::bigint), '-2013265921'::integer) <= 0)))
+```
+
+
 ### Recursive Planning When FROM Clause has Reference Table (or Recurring Tuples)
 
 This section discusses a specific scenario in Citus's recursive query planning: handling queries where the main query's `FROM` clause is recurring, but there are subqueries in the `SELECT` or `WHERE` clauses involving distributed tables.

src/backend/distributed/citus.control

@@ -1,6 +1,6 @@
 # Citus extension
 comment = 'Citus distributed database'
-default_version = '13.2-1'
+default_version = '14.0-1'
 module_pathname = '$libdir/citus'
 relocatable = false
 schema = pg_catalog

src/backend/distributed/commands/index.c

@@ -854,8 +854,11 @@ PostprocessIndexStmt(Node *node, const char *queryString)
 	table_close(relation, NoLock);
 	index_close(indexRelation, NoLock);
 
+	PushActiveSnapshot(GetTransactionSnapshot());
+
 	/* mark index as invalid, in-place (cannot be rolled back) */
 	index_set_state_flags(indexRelationId, INDEX_DROP_CLEAR_VALID);
+	PopActiveSnapshot();
 
 	/* re-open a transaction command from here on out */
 	CommitTransactionCommand();
@@ -1370,8 +1373,11 @@ MarkIndexValid(IndexStmt *indexStmt)
 											schemaId);
 	Relation indexRelation = index_open(indexRelationId, RowExclusiveLock);
 
+	PushActiveSnapshot(GetTransactionSnapshot());
+
 	/* mark index as valid, in-place (cannot be rolled back) */
 	index_set_state_flags(indexRelationId, INDEX_CREATE_SET_VALID);
+	PopActiveSnapshot();
 
 	table_close(relation, NoLock);
 	index_close(indexRelation, NoLock);

src/backend/distributed/commands/statistics.c

@@ -69,7 +69,15 @@ PreprocessCreateStatisticsStmt(Node *node, const char *queryString,
 {
 	CreateStatsStmt *stmt = castNode(CreateStatsStmt, node);
 
-	RangeVar *relation = (RangeVar *) linitial(stmt->relations);
+	Node *relationNode = (Node *) linitial(stmt->relations);
+
+	if (!IsA(relationNode, RangeVar))
+	{
+		return NIL;
+	}
+
+	RangeVar *relation = (RangeVar *) relationNode;
+
 	Oid relationId = RangeVarGetRelid(relation, ShareUpdateExclusiveLock, false);
 
 	if (!IsCitusTable(relationId) || !ShouldPropagate())

src/backend/distributed/deparser/ruleutils_18.c

@@ -3804,6 +3804,8 @@ get_update_query_targetlist_def(Query *query, List *targetList,
 	SubLink    *cur_ma_sublink;
 	List	   *ma_sublinks;
 
+	targetList = ExpandMergedSubscriptingRefEntries(targetList);
+
 	/*
 	 * Prepare to deal with MULTIEXPR assignments: collect the source SubLinks
 	 * into a list.  We expect them to appear, in ID order, in resjunk tlist
@@ -3827,6 +3829,8 @@ get_update_query_targetlist_def(Query *query, List *targetList,
 				}
 			}
 		}
+
+		ensure_update_targetlist_in_param_order(targetList);
 	}
 	next_ma_cell = list_head(ma_sublinks);
 	cur_ma_sublink = NULL;

src/backend/distributed/planner/merge_planner.c

@@ -41,6 +41,7 @@
 static int SourceResultPartitionColumnIndex(Query *mergeQuery,
 											List *sourceTargetList,
 											CitusTableCacheEntry *targetRelation);
+static int FindTargetListEntryWithVarExprAttno(List *targetList, AttrNumber varattno);
 static Var * ValidateAndReturnVarIfSupported(Node *entryExpr);
 static DeferredErrorMessage * DeferErrorIfTargetHasFalseClause(Oid targetRelationId,
 															   PlannerRestrictionContext *
@@ -422,10 +423,13 @@ ErrorIfMergeHasUnsupportedTables(Oid targetRelationId, List *rangeTableList)
 			case RTE_VALUES:
 			case RTE_JOIN:
 			case RTE_CTE:
-			{
+#if PG_VERSION_NUM >= PG_VERSION_18
-				/* Skip them as base table(s) will be checked */
+			case RTE_GROUP:
-				continue;
+#endif
-			}
+				{
+					/* Skip them as base table(s) will be checked */
+					continue;
+				}
 
 			/*
 			 * RTE_NAMEDTUPLESTORE is typically used in ephmeral named relations,
@@ -628,6 +632,22 @@ MergeQualAndTargetListFunctionsSupported(Oid resultRelationId, Query *query,
 			}
 		}
 
+		/*
+		 * joinTree->quals, retrieved by GetMergeJoinTree() - either from
+		 * mergeJoinCondition (PG >= 17) or jointree->quals (PG < 17),
+		 * only contains the quals that present in "ON (..)" clause. Action
+		 * quals that can be specified for each specific action, as in
+		 * "WHEN <match condition> AND <action quals> THEN <action>"", are
+		 * saved into "qual" field of the corresponding action's entry in
+		 * mergeActionList, see
+		 * https://github.com/postgres/postgres/blob/e6da68a6e1d60a037b63a9c9ed36e5ef0a996769/src/backend/parser/parse_merge.c#L285-L293.
+		 *
+		 * For this reason, even if TargetEntryChangesValue() could prove that
+		 * an action's quals ensure that the action cannot change the distribution
+		 * key, this is not the case as we don't provide action quals to
+		 * TargetEntryChangesValue(), but just joinTree, which only contains
+		 * the "ON (..)" clause quals.
+		 */
 		if (targetEntryDistributionColumn &&
 			TargetEntryChangesValue(targetEntry, distributionColumn, joinTree))
 		{
@@ -1411,7 +1431,8 @@ SourceResultPartitionColumnIndex(Query *mergeQuery, List *sourceTargetList,
 	Assert(sourceRepartitionVar);
 
 	int sourceResultRepartitionColumnIndex =
-		DistributionColumnIndex(sourceTargetList, sourceRepartitionVar);
+		FindTargetListEntryWithVarExprAttno(sourceTargetList,
+											sourceRepartitionVar->varattno);
 
 	if (sourceResultRepartitionColumnIndex == -1)
 	{
@@ -1562,6 +1583,33 @@ FetchAndValidateInsertVarIfExists(Oid targetRelationId, Query *query)
 }
 
 
+/*
+ * FindTargetListEntryWithVarExprAttno finds the index of the target
+ * entry whose expr is a Var that points to input varattno.
+ *
+ * If no such target entry is found, it returns -1.
+ */
+static int
+FindTargetListEntryWithVarExprAttno(List *targetList, AttrNumber varattno)
+{
+	int targetEntryIndex = 0;
+
+	TargetEntry *targetEntry = NULL;
+	foreach_declared_ptr(targetEntry, targetList)
+	{
+		if (IsA(targetEntry->expr, Var) &&
+			((Var *) targetEntry->expr)->varattno == varattno)
+		{
+			return targetEntryIndex;
+		}
+
+		targetEntryIndex++;
+	}
+
+	return -1;
+}
+
+
 /*
  * IsLocalTableModification returns true if the table modified is a Postgres table.
  * We do not support recursive planning for MERGE yet, so we could have a join

src/backend/distributed/planner/multi_physical_planner.c

@@ -3173,16 +3173,25 @@ BuildBaseConstraint(Var *column)
 
 
 /*
- * MakeOpExpression builds an operator expression node. This operator expression
+ * MakeOpExpressionExtended builds an operator expression node that's of
- * implements the operator clause as defined by the variable and the strategy
+ * the form "Var <op> Expr", where, Expr must either be a Const or a Var
- * number.
+ * (*1).
+ *
+ * This operator expression implements the operator clause as defined by
+ * the variable and the strategy number.
  */
 OpExpr *
-MakeOpExpression(Var *variable, int16 strategyNumber)
+MakeOpExpressionExtended(Var *leftVar, Expr *rightArg, int16 strategyNumber)
 {
-	Oid typeId = variable->vartype;
+	/*
-	Oid typeModId = variable->vartypmod;
+	 * Other types of expressions are probably also fine to be used, but
-	Oid collationId = variable->varcollid;
+	 * none of the callers need support for them for now, so we haven't
+	 * tested them (*1).
+	 */
+	Assert(IsA(rightArg, Const) || IsA(rightArg, Var));
+
+	Oid typeId = leftVar->vartype;
+	Oid collationId = leftVar->varcollid;
 
 	Oid accessMethodId = BTREE_AM_OID;
 
@@ -3200,18 +3209,16 @@ MakeOpExpression(Var *variable, int16 strategyNumber)
 	 */
 	if (operatorClassInputType != typeId && typeType != TYPTYPE_PSEUDO)
 	{
-		variable = (Var *) makeRelabelType((Expr *) variable, operatorClassInputType,
+		leftVar = (Var *) makeRelabelType((Expr *) leftVar, operatorClassInputType,
-										   -1, collationId, COERCE_IMPLICIT_CAST);
+										  -1, collationId, COERCE_IMPLICIT_CAST);
 	}
 
-	Const *constantValue = makeNullConst(operatorClassInputType, typeModId, collationId);
-
 	/* Now make the expression with the given variable and a null constant */
 	OpExpr *expression = (OpExpr *) make_opclause(operatorId,
 												  InvalidOid, /* no result type yet */
 												  false, /* no return set */
-												  (Expr *) variable,
+												  (Expr *) leftVar,
-												  (Expr *) constantValue,
+												  rightArg,
 												  InvalidOid, collationId);
 
 	/* Set implementing function id and result type */
@@ -3222,6 +3229,31 @@ MakeOpExpression(Var *variable, int16 strategyNumber)
 }
 
 
+/*
+ * MakeOpExpression is a wrapper around MakeOpExpressionExtended
+ * that creates a null constant of the appropriate type for right
+ * hand side operator class input type. As a result, it builds an
+ * operator expression node that's of the form "Var <op> NULL".
+ */
+OpExpr *
+MakeOpExpression(Var *leftVar, int16 strategyNumber)
+{
+	Oid typeId = leftVar->vartype;
+	Oid typeModId = leftVar->vartypmod;
+	Oid collationId = leftVar->varcollid;
+
+	Oid accessMethodId = BTREE_AM_OID;
+
+	OperatorCacheEntry *operatorCacheEntry = LookupOperatorByType(typeId, accessMethodId,
+																  strategyNumber);
+	Oid operatorClassInputType = operatorCacheEntry->operatorClassInputType;
+
+	Const *constantValue = makeNullConst(operatorClassInputType, typeModId, collationId);
+
+	return MakeOpExpressionExtended(leftVar, (Expr *) constantValue, strategyNumber);
+}
+
+
 /*
  * LookupOperatorByType is a wrapper around GetOperatorByType(),
  * operatorClassInputType() and get_typtype() functions that uses a cache to avoid

src/backend/distributed/planner/multi_router_planner.c

@@ -372,6 +372,25 @@ AddPartitionKeyNotNullFilterToSelect(Query *subqery)
 	/* we should have found target partition column */
 	Assert(targetPartitionColumnVar != NULL);
 
+#if PG_VERSION_NUM >= PG_VERSION_18
+	if (subqery->hasGroupRTE)
+	{
+		/* if the partition column is a grouped column, we need to flatten it
+		 * to ensure query deparsing works correctly. We choose to do this here
+		 * instead of in ruletils.c because we want to keep the flattening logic
+		 * close to the NOT NULL filter injection.
+		 */
+		RangeTblEntry *partitionRTE = rt_fetch(targetPartitionColumnVar->varno,
+											   subqery->rtable);
+		if (partitionRTE->rtekind == RTE_GROUP)
+		{
+			targetPartitionColumnVar = (Var *) flatten_group_exprs(NULL, subqery,
+																   (Node *)
+																   targetPartitionColumnVar);
+		}
+	}
+#endif
+
 	/* create expression for partition_column IS NOT NULL */
 	NullTest *nullTest = makeNode(NullTest);
 	nullTest->nulltesttype = IS_NOT_NULL;
@@ -1609,10 +1628,19 @@ MasterIrreducibleExpressionFunctionChecker(Oid func_id, void *context)
 
 /*
  * TargetEntryChangesValue determines whether the given target entry may
- * change the value in a given column, given a join tree. The result is
+ * change the value given a column and a join tree.
- * true unless the expression refers directly to the column, or the
+ *
- * expression is a value that is implied by the qualifiers of the join
+ * The function assumes that the "targetEntry" references given "column"
- * tree, or the target entry sets a different column.
+ * Var via its "resname" and is used as part of a modify query. This means
+ * that, for example, for an update query, the input "targetEntry" constructs
+ * the following assignment operation as part of the SET clause:
+ *   "col_a = expr_a ", where, "col_a" refers to input "column" Var (via
+ * "resname") as per the assumption written above. And we want to understand
+ * if "expr_a" (which is pointed to by targetEntry->expr) refers directly to
+ * the "column" Var, or "expr_a" is a value that is implied to be equal
+ * to "column" Var by the qualifiers of the join tree. If so, we know that
+ * the value of "col_a" effectively cannot be changed by this assignment
+ * operation.
  */
 bool
 TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTree)
@@ -1623,11 +1651,36 @@ TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTre
 	if (IsA(setExpr, Var))
 	{
 		Var *newValue = (Var *) setExpr;
-		if (newValue->varattno == column->varattno)
+		if (column->varno == newValue->varno &&
+			column->varattno == newValue->varattno)
 		{
-			/* target entry of the form SET col = table.col */
+			/*
+			 * Target entry is of the form "SET col_a = foo.col_b",
+			 * where foo also points to the same range table entry
+			 * and col_a and col_b are the same. So, effectively
+			 * they're literally referring to the same column.
+			 */
 			isColumnValueChanged = false;
 		}
+		else
+		{
+			List *restrictClauseList = WhereClauseList(joinTree);
+			OpExpr *equalityExpr = MakeOpExpressionExtended(column, (Expr *) newValue,
+															BTEqualStrategyNumber);
+
+			bool predicateIsImplied = predicate_implied_by(list_make1(equalityExpr),
+														   restrictClauseList, false);
+			if (predicateIsImplied)
+			{
+				/*
+				 * Target entry is of the form
+				 * "SET col_a = foo.col_b WHERE col_a = foo.col_b (AND (...))",
+				 * where foo points to a different relation or it points
+				 * to the same relation but col_a is not the same column as col_b.
+				 */
+				isColumnValueChanged = false;
+			}
+		}
 	}
 	else if (IsA(setExpr, Const))
 	{
@@ -1648,7 +1701,10 @@ TargetEntryChangesValue(TargetEntry *targetEntry, Var *column, FromExpr *joinTre
 													   restrictClauseList, false);
 		if (predicateIsImplied)
 		{
-			/* target entry of the form SET col = <x> WHERE col = <x> AND ... */
+			/*
+			 * Target entry is of the form
+			 * "SET col_a = const_a WHERE col_a = const_a (AND (...))".
+			 */
 			isColumnValueChanged = false;
 		}
 	}

src/backend/distributed/planner/query_pushdown_planning.c

@@ -2029,7 +2029,9 @@ SubqueryPushdownMultiNodeTree(Query *originalQuery)
 	pushedDownQuery->setOperations = copyObject(queryTree->setOperations);
 	pushedDownQuery->querySource = queryTree->querySource;
 	pushedDownQuery->hasSubLinks = queryTree->hasSubLinks;
-
+#if PG_VERSION_NUM >= PG_VERSION_18
+	pushedDownQuery->hasGroupRTE = queryTree->hasGroupRTE;
+#endif
 	MultiTable *subqueryNode = MultiSubqueryPushdownTable(pushedDownQuery);
 
 	SetChild((MultiUnaryNode *) subqueryCollectNode, (MultiNode *) subqueryNode);

src/backend/distributed/planner/relation_restriction_equivalence.c

@@ -2431,7 +2431,7 @@ FilterJoinRestrictionContext(JoinRestrictionContext *joinRestrictionContext, Rel
 
 /*
  * RangeTableArrayContainsAnyRTEIdentities returns true if any of the range table entries
- * int rangeTableEntries array is an range table relation specified in queryRteIdentities.
+ * in rangeTableEntries array is a range table relation specified in queryRteIdentities.
  */
 static bool
 RangeTableArrayContainsAnyRTEIdentities(RangeTblEntry **rangeTableEntries, int
@@ -2444,6 +2444,18 @@ RangeTableArrayContainsAnyRTEIdentities(RangeTblEntry **rangeTableEntries, int
 		List *rangeTableRelationList = NULL;
 		ListCell *rteRelationCell = NULL;
 
+#if PG_VERSION_NUM >= PG_VERSION_18
+
+		/*
+		 * In PG18+, planner array simple_rte_array may contain NULL entries
+		 * for "dead relations". See PG commits 5f6f951 and e9a20e4 for details.
+		 */
+		if (rangeTableEntry == NULL)
+		{
+			continue;
+		}
+#endif
+
 		/*
 		 * Get list of all RTE_RELATIONs in the given range table entry
 		 * (i.e.,rangeTableEntry could be a subquery where we're interested

src/backend/distributed/sql/citus--13.2-1--14.0-1.sql

@@ -0,0 +1,2 @@
+-- citus--13.2-1--14.0-1
+-- bump version to 14.0-1

src/backend/distributed/sql/downgrades/citus--14.0-1--13.2-1.sql

@@ -0,0 +1,2 @@
+-- citus--14.0-1--13.2-1
+-- downgrade version to 13.2-1

src/include/distributed/multi_physical_planner.h

@@ -586,7 +586,8 @@ extern DistributedPlan * CreatePhysicalDistributedPlan(MultiTreeRoot *multiTree,
 													   plannerRestrictionContext);
 extern Task * CreateBasicTask(uint64 jobId, uint32 taskId, TaskType taskType,
 							  char *queryString);
-
+extern OpExpr * MakeOpExpressionExtended(Var *leftVar, Expr *rightArg,
+										 int16 strategyNumber);
 extern OpExpr * MakeOpExpression(Var *variable, int16 strategyNumber);
 extern Node *  WrapUngroupedVarsInAnyValueAggregate(Node *expression,
 													List *groupClauseList,

src/test/regress/bin/normalize.sed

@@ -359,3 +359,9 @@ s/(Actual[[:space:]]+Rows:[[:space:]]*)N\.N/\1N/gI
 s/^([ \t]*)List of tables$/\1List of relations/g
 s/^([ \t]*)List of indexes$/\1List of relations/g
 s/^([ \t]*)List of sequences$/\1List of relations/g
+
+# --- PG18 FK wording -> legacy generic form ---
+# e.g., "violates RESTRICT setting of foreign key constraint" -> "violates foreign key constraint"
+s/violates RESTRICT setting of foreign key constraint/violates foreign key constraint/g
+# DETAIL line changed "is referenced" -> old "is still referenced"
+s/\<is referenced from table\>/is still referenced from table/g

src/test/regress/citus_tests/config.py

@@ -49,7 +49,7 @@ CITUS_ARBITRARY_TEST_DIR = "./tmp_citus_test"
 
 MASTER = "master"
 # This should be updated when citus version changes
-MASTER_VERSION = "13.2"
+MASTER_VERSION = "14.0"
 
 HOME = expanduser("~")
 

src/test/regress/expected/isolation_merge_0.out

@@ -1,5 +0,0 @@
-Parsed test spec with 2 sessions
-
-starting permutation: s1-begin s1-upd-ins s2-result s1-commit s2-result
-setup failed: ERROR:  MERGE is not supported on PG versions below 15
-CONTEXT:  PL/pgSQL function inline_code_block line XX at RAISE

src/test/regress/expected/isolation_merge_replicated_0.out

@@ -1,5 +0,0 @@
-Parsed test spec with 2 sessions
-
-starting permutation: s1-begin s1-upd-ins s2-begin s2-update s1-commit s2-commit s1-result s2-result
-setup failed: ERROR:  MERGE is not supported on PG versions below 15
-CONTEXT:  PL/pgSQL function inline_code_block line XX at RAISE

src/test/regress/expected/merge_repartition2.out

@@ -193,13 +193,148 @@ SQL function "compare_data" statement 2
 
 (1 row)
 
+---- https://github.com/citusdata/citus/issues/8180 ----
+CREATE TABLE dist_1 (a int, b int, c int);
+CREATE TABLE dist_2 (a int, b int, c int);
+CREATE TABLE dist_different_order_1 (b int, a int, c int);
+SELECT create_distributed_table('dist_1', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_2', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_different_order_1', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+MERGE INTO dist_1
+USING dist_2
+ON (dist_1.a = dist_2.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2.b;
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET b = src.b;
+MERGE INTO dist_different_order_1
+USING dist_1
+ON (dist_different_order_1.a = dist_1.b)
+WHEN MATCHED THEN UPDATE SET b = dist_1.b;
+CREATE TABLE dist_1_cast (a int, b int);
+CREATE TABLE dist_2_cast (a int, b numeric);
+SELECT create_distributed_table('dist_1_cast', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_2_cast', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+MERGE INTO dist_1_cast
+USING dist_2_cast
+ON (dist_1_cast.a = dist_2_cast.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2_cast.b;
+ERROR:  In the MERGE ON clause, there is a datatype mismatch between target's distribution column and the expression originating from the source.
+DETAIL:  If the types are different, Citus uses different hash functions for the two column types, which might lead to incorrect repartitioning of the result data
+MERGE INTO dist_1_cast
+USING (SELECT a, b::int as b FROM dist_2_cast) dist_2_cast
+ON (dist_1_cast.a = dist_2_cast.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2_cast.b;
+-- a more sophisticated example
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+SELECT create_distributed_table('dist_source', 'tstamp_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_target', 'int_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+-- execute the query on distributed tables
+MERGE INTO dist_target target_alias
+USING dist_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+MERGE INTO local_target target_alias
+USING local_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+-- compare both targets
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+ targets_match
+---------------------------------------------------------------------
+ t
+(1 row)
+
+SET client_min_messages TO WARNING;
 DROP SCHEMA merge_repartition2_schema CASCADE;
-NOTICE:  drop cascades to 8 other objects
-DETAIL:  drop cascades to table pg_target
-drop cascades to table pg_source
-drop cascades to function cleanup_data()
-drop cascades to function setup_data()
-drop cascades to function check_data(text,text,text,text)
-drop cascades to function compare_data()
-drop cascades to table citus_target
-drop cascades to table citus_source

src/test/regress/expected/mixed_relkind_tests.out

@@ -394,9 +394,9 @@ DEBUG:  Wrapping relation "mat_view_on_part_dist" "foo" to a subquery
 DEBUG:  generating subplan XXX_1 for subquery SELECT a FROM mixed_relkind_tests.mat_view_on_part_dist foo WHERE true
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: UPDATE mixed_relkind_tests.partitioned_distributed_table SET a = foo.a FROM (SELECT foo_1.a, NULL::integer AS b FROM (SELECT intermediate_result.a FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(a integer)) foo_1) foo WHERE (foo.a OPERATOR(pg_catalog.=) partitioned_distributed_table.a)
 UPDATE partitioned_distributed_table SET a = foo.a FROM partitioned_distributed_table AS foo WHERE foo.a < partitioned_distributed_table.a;
-ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
+ERROR:  modifying the partition value of rows is not allowed
 UPDATE partitioned_distributed_table SET a = foo.a FROM distributed_table AS foo WHERE foo.a < partitioned_distributed_table.a;
-ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
+ERROR:  modifying the partition value of rows is not allowed
 -- should work
 UPDATE partitioned_distributed_table SET a = foo.a FROM partitioned_distributed_table AS foo WHERE foo.a = partitioned_distributed_table.a;
 UPDATE partitioned_distributed_table SET a = foo.a FROM view_on_part_dist AS foo WHERE foo.a = partitioned_distributed_table.a;

src/test/regress/expected/multi_extension.out

@@ -1652,12 +1652,28 @@ SELECT * FROM multi_extension.print_extension_changes();
                                                                                                                       | view citus_stats
 (12 rows)
 
+-- Test downgrade to 13.2-1 from 14.0-1
+ALTER EXTENSION citus UPDATE TO '14.0-1';
+ALTER EXTENSION citus UPDATE TO '13.2-1';
+-- Should be empty result since upgrade+downgrade should be a no-op
+SELECT * FROM multi_extension.print_extension_changes();
+ previous_object | current_object
+---------------------------------------------------------------------
+(0 rows)
+
+-- Snapshot of state at 14.0-1
+ALTER EXTENSION citus UPDATE TO '14.0-1';
+SELECT * FROM multi_extension.print_extension_changes();
+ previous_object | current_object
+---------------------------------------------------------------------
+(0 rows)
+
 DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 -- show running version
 SHOW citus.version;
  citus.version
 ---------------------------------------------------------------------
- 13.2devel
+ 14.0devel
 (1 row)
 
 -- ensure no unexpected objects were created outside pg_catalog
@@ -1692,7 +1708,7 @@ DROP EXTENSION citus;
 DROP EXTENSION citus_columnar;
 CREATE EXTENSION citus VERSION '8.0-1';
 ERROR:  specified version incompatible with loaded Citus library
-DETAIL:  Loaded library requires 13.2, but 8.0-1 was specified.
+DETAIL:  Loaded library requires 14.0, but 8.0-1 was specified.
 HINT:  If a newer library is present, restart the database and try the command again.
 -- Test non-distributed queries work even in version mismatch
 SET citus.enable_version_checks TO 'false';
@@ -1737,7 +1753,7 @@ ORDER BY 1;
 -- We should not distribute table in version mistmatch
 SELECT create_distributed_table('version_mismatch_table', 'column1');
 ERROR:  loaded Citus library version differs from installed extension version
-DETAIL:  Loaded library requires 13.2, but the installed extension version is 8.1-1.
+DETAIL:  Loaded library requires 14.0, but the installed extension version is 8.1-1.
 HINT:  Run ALTER EXTENSION citus UPDATE and try again.
 -- This function will cause fail in next ALTER EXTENSION
 CREATE OR REPLACE FUNCTION pg_catalog.relation_is_a_known_shard(regclass)

src/test/regress/expected/multi_modifications.out

@@ -2,6 +2,7 @@ SET citus.shard_count TO 32;
 SET citus.next_shard_id TO 750000;
 SET citus.next_placement_id TO 750000;
 CREATE SCHEMA multi_modifications;
+SET search_path TO multi_modifications;
 -- some failure messages that comes from the worker nodes
 -- might change due to parallel executions, so suppress those
 -- using \set VERBOSITY terse
@@ -31,8 +32,12 @@ SELECT create_distributed_table('limit_orders', 'id', 'hash');
 
 (1 row)
 
-SELECT create_distributed_table('multiple_hash', 'id', 'hash');
+SELECT create_distributed_table('multiple_hash', 'category', 'hash');
-ERROR:  column "id" of relation "multiple_hash" does not exist
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
 SELECT create_distributed_table('range_partitioned', 'id', 'range');
  create_distributed_table
 ---------------------------------------------------------------------
@@ -344,22 +349,26 @@ ERROR:  duplicate key value violates unique constraint "limit_orders_pkey_750001
 -- Test that shards which miss a modification are marked unhealthy
 -- First: Connect to the second worker node
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE limit_orders_750000 RENAME TO renamed_orders;
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 -- Fourth: Perform an INSERT on the remaining node
 -- the whole transaction should fail
 \set VERBOSITY terse
 INSERT INTO limit_orders VALUES (276, 'ADR', 140, '2007-07-02 16:32:15', 'sell', 43.67);
-ERROR:  relation "public.limit_orders_750000" does not exist
+ERROR:  relation "multi_modifications.limit_orders_750000" does not exist
 -- set the shard name back
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE renamed_orders RENAME TO limit_orders_750000;
 -- Verify the insert failed and both placements are healthy
 -- or the insert succeeded and placement marked unhealthy
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
  count
 ---------------------------------------------------------------------
@@ -367,6 +376,7 @@ SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
 (1 row)
 
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
  count
 ---------------------------------------------------------------------
@@ -374,6 +384,7 @@ SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
 (1 row)
 
 \c - - - :master_port
+SET search_path TO multi_modifications;
 SELECT count(*) FROM limit_orders WHERE id = 276;
  count
 ---------------------------------------------------------------------
@@ -394,14 +405,16 @@ AND    s.logicalrelid = 'limit_orders'::regclass;
 -- Test that if all shards miss a modification, no state change occurs
 -- First: Connect to the first worker node
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE limit_orders_750000 RENAME TO renamed_orders;
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 -- Fourth: Perform an INSERT on the remaining node
 \set VERBOSITY terse
 INSERT INTO limit_orders VALUES (276, 'ADR', 140, '2007-07-02 16:32:15', 'sell', 43.67);
-ERROR:  relation "public.limit_orders_750000" does not exist
+ERROR:  relation "multi_modifications.limit_orders_750000" does not exist
 \set VERBOSITY DEFAULT
 -- Last: Verify worker is still healthy
 SELECT count(*)
@@ -420,10 +433,12 @@ AND    s.logicalrelid = 'limit_orders'::regclass;
 -- Undo our change...
 -- First: Connect to the first worker node
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE renamed_orders RENAME TO limit_orders_750000;
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 -- attempting to change the partition key is unsupported
 UPDATE limit_orders SET id = 0 WHERE id = 246;
 ERROR:  modifying the partition value of rows is not allowed
@@ -433,6 +448,368 @@ ERROR:  modifying the partition value of rows is not allowed
 UPDATE limit_orders SET id = 246 WHERE id = 246;
 UPDATE limit_orders SET id = 246 WHERE id = 246 AND symbol = 'GM';
 UPDATE limit_orders SET id = limit_orders.id WHERE id = 246;
+CREATE TABLE dist_1 (a int, b int, c int);
+CREATE TABLE dist_2 (a int, b int, c int);
+CREATE TABLE dist_non_colocated (a int, b int, c int);
+CREATE TABLE dist_different_order_1 (b int, a int, c int);
+SELECT create_distributed_table('dist_1', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_2', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_non_colocated', 'a', colocate_with=>'none');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_different_order_1', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+--
+-- https://github.com/citusdata/citus/issues/8087
+--
+---- update: should work ----
+-- setting shard key to itself --
+UPDATE dist_1 SET a = dist_1.a;
+UPDATE dist_1 SET a = dist_1.a WHERE dist_1.a > dist_1.b AND dist_1.b > 10;
+UPDATE dist_1 SET a = dist_1.a FROM dist_2 WHERE dist_1.a = dist_2.a;
+-- setting shard key to another var that's implied to be equal to shard key --
+UPDATE dist_1 SET a = b WHERE a = b;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a AND dist_1.b = dist_2.c AND (dist_2.c > 5 OR dist_2.c < 0);
+with cte as (
+select a, b from dist_1
+)
+update dist_1 set a = cte.a from cte where dist_1.a = cte.a;
+with cte as (
+select a as x, b as y from (select a, b from dist_1 limit 100) dt where b > 100
+)
+update dist_1 set a = cte.x from cte where dist_1.a = cte.x;
+with cte as (
+select d2.a as x, d1.b as y
+from dist_1 d1, dist_different_order_1 d2
+where d1.a=d2.a)
+update dist_1  set a = cte.x from cte where y != 0 and dist_1.a = cte.x;
+with cte as (
+select * from (select a as x, b as y from dist_2 limit 100) q
+)
+update dist_1 set a = cte.x from cte where b = cte.y and cte.y = a and a = cte.x;
+-- supported although the where clause will certainly eval to false
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a AND dist_1.a = 5 AND dist_2.a = 7;
+-- setting shard key to another var that's implied to be equal to shard key, repeat with dist_different_order_1 --
+UPDATE dist_1 SET a = dist_different_order_1.a FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a;
+-- test with extra quals
+UPDATE dist_1 SET a = dist_different_order_1.a FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a AND dist_1.b = dist_different_order_1.c AND (dist_different_order_1.c > 5 OR dist_different_order_1.c < 0);
+---- update: errors in router planner ----
+-- different column of the same relation, which is not implied to be equal to shard key --
+UPDATE dist_1 SET a = dist_1.b;
+ERROR:  modifying the partition value of rows is not allowed
+-- another range table entry's column with the same attno, which is not implied to be equal to shard key --
+UPDATE dist_1 SET a = dist_2.a FROM dist_2;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a != dist_2.a;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a >= dist_2.a;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a OR dist_1.a > dist_2.a;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = dist_different_order_1.b FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = foo.a FROM dist_1 foo;
+ERROR:  modifying the partition value of rows is not allowed
+UPDATE dist_1 SET a = foo.a FROM dist_1 foo WHERE dist_1.a != foo.a;
+ERROR:  modifying the partition value of rows is not allowed
+-- (*1) Would normally expect this to not throw an error because
+-- dist_1.a = dist_2.b AND dist_2.b = dist_2.a,
+-- so dist_1.a = dist_2.a, so we should be able to deduce
+-- that (dist_1.)a = dist_2.a, but seems predicate_implied_by()
+-- is not that smart.
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.b AND dist_2.b = dist_2.a;
+ERROR:  modifying the partition value of rows is not allowed
+-- and same here
+with cte as (
+select * from (select a as x, b as y from dist_different_order_1 limit 100) q
+)
+update dist_1 set a = cte.x from cte where a = cte.y and cte.y = b and b = cte.x;
+ERROR:  modifying the partition value of rows is not allowed
+---- update: errors later (in logical or physical planner) ----
+-- setting shard key to itself --
+UPDATE dist_1 SET a = dist_1.a FROM dist_1 foo;
+ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
+UPDATE dist_1 SET a = dist_1.a FROM dist_2 foo;
+ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
+-- setting shard key to another var that's implied to be equal to shard key --
+UPDATE dist_1 SET a = dist_non_colocated.a FROM dist_non_colocated WHERE dist_1.a = dist_non_colocated.a;
+ERROR:  cannot push down this subquery
+DETAIL:  dist_1 and dist_non_colocated are not colocated
+UPDATE dist_1 SET a = dist_2.b FROM dist_2 WHERE dist_1.a = dist_2.b;
+ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
+---- update: a more sophisticated example ----
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+SELECT create_distributed_table('dist_source', 'int_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_target', 'int_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+-- execute the query on distributed tables
+UPDATE dist_target target_alias
+SET int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+FROM dist_source source_alias
+WHERE target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col;
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+UPDATE local_target target_alias
+SET int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+FROM local_source source_alias
+WHERE target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col;
+-- compare both targets
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+ targets_match
+---------------------------------------------------------------------
+ t
+(1 row)
+
+---- merge: should work ----
+-- setting shard key to itself --
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.a;
+-- We don't care about action quals when deciding if the update
+-- could change the shard key, but still add some action quals for
+-- testing. See the comments written on top of the line we call
+-- TargetEntryChangesValue() in MergeQualAndTargetListFunctionsSupported().
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED AND dist_1.a > dist_1.b AND dist_1.b > 10 THEN UPDATE SET a = dist_1.a;
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.a;
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+-- setting shard key to another var that's implied to be equal to shard key --
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = dist_1.b)
+WHEN MATCHED THEN UPDATE SET a = dist_1.b;
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+-- test with extra quals
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b AND (dist_1.b > 1000 OR (dist_1.b < 500)))
+WHEN MATCHED THEN UPDATE SET a = src.b;
+-- setting shard key to another var that's implied to be equal to shard key, repeat with dist_different_order_1 --
+MERGE INTO dist_1
+USING dist_different_order_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+---- merge: errors in router planner ----
+-- different column of the same relation, which is not implied to be equal to shard key --
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.b;
+ERROR:  updating the distribution column is not allowed in MERGE actions
+-- another range table entry's column with the same attno, which is not implied to be equal to shard key --
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+ERROR:  updating the distribution column is not allowed in MERGE actions
+-- as in (*1), this is not supported
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b AND src.b = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+ERROR:  updating the distribution column is not allowed in MERGE actions
+MERGE INTO dist_1
+USING dist_2 src
+ON (true)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+ERROR:  updating the distribution column is not allowed in MERGE actions
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a <= src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+ERROR:  updating the distribution column is not allowed in MERGE actions
+---- merge: a more sophisticated example ----
+DROP TABLE dist_source, dist_target, local_source, local_target;
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+SELECT create_distributed_table('dist_source', 'tstamp_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT create_distributed_table('dist_target', 'int_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+-- execute the query on distributed tables
+MERGE INTO dist_target target_alias
+USING dist_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+MERGE INTO local_target target_alias
+USING local_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+-- compare both targets
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+ targets_match
+---------------------------------------------------------------------
+ t
+(1 row)
+
 -- UPDATEs with a FROM clause are supported even with local tables
 UPDATE limit_orders SET limit_price = 0.00 FROM bidders
 					WHERE limit_orders.id = 246 AND
@@ -1353,19 +1730,5 @@ CREATE TABLE multi_modifications.local (a int default 1, b int);
 INSERT INTO multi_modifications.local VALUES (default, (SELECT min(id) FROM summary_table));
 ERROR:  subqueries are not supported within INSERT queries
 HINT:  Try rewriting your queries with 'INSERT INTO ... SELECT' syntax.
-DROP TABLE insufficient_shards;
+SET client_min_messages TO WARNING;
-DROP TABLE raw_table;
-DROP TABLE summary_table;
-DROP TABLE reference_raw_table;
-DROP TABLE reference_summary_table;
-DROP TABLE limit_orders;
-DROP TABLE multiple_hash;
-DROP TABLE range_partitioned;
-DROP TABLE append_partitioned;
-DROP TABLE bidders;
-DROP FUNCTION stable_append;
-DROP FUNCTION immutable_append;
-DROP FUNCTION temp_strict_func;
-DROP TYPE order_side;
 DROP SCHEMA multi_modifications CASCADE;
-NOTICE:  drop cascades to table multi_modifications.local

src/test/regress/expected/multi_test_catalog_views.out

@@ -70,15 +70,19 @@ SELECT "name" AS "Column",
 	   "relid"
 FROM table_attrs;
 
-CREATE VIEW table_checks AS
+CREATE OR REPLACE VIEW table_checks AS
-SELECT cc.constraint_name AS "Constraint",
+SELECT
-       ('CHECK ' || regexp_replace(check_clause, '^\((.*)\)$', '\1')) AS "Definition",
+  c.conname AS "Constraint",
-       format('%I.%I', ccu.table_schema, ccu.table_name)::regclass::oid AS relid
+  'CHECK ' ||
-FROM information_schema.check_constraints cc,
+  -- drop a single pair of outer parens if the deparser adds them
-     information_schema.constraint_column_usage ccu
+  regexp_replace(pg_get_expr(c.conbin, c.conrelid, true), '^\((.*)\)$', '\1')
-WHERE cc.constraint_schema = ccu.constraint_schema AND
+    AS "Definition",
-      cc.constraint_name = ccu.constraint_name
+  c.conrelid AS relid
-ORDER BY cc.constraint_name ASC;
+FROM pg_catalog.pg_constraint AS c
+WHERE c.contype <> 'n'         -- drop NOT NULL
+  AND c.conbin IS NOT NULL     -- only things with an expression (i.e., CHECKs)
+  AND c.conrelid <> 0          -- table-level (exclude domain checks)
+ORDER BY "Constraint", "Definition";
 
 CREATE VIEW index_attrs AS
 WITH indexoid AS (

src/test/regress/expected/pg18.out

@@ -0,0 +1,169 @@
+--
+-- PG18
+--
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 18 AS server_version_ge_18
+\gset
+-- test invalid statistics
+-- behavior is same among PG versions, error message differs
+-- relevant PG18 commit: 3eea4dc2c7
+CREATE STATISTICS tst ON a FROM (VALUES (x)) AS foo;
+ERROR:  cannot create statistics on the specified relation
+DETAIL:  CREATE STATISTICS only supports tables, foreign tables and materialized views.
+\if :server_version_ge_18
+\else
+\q
+\endif
+-- PG18-specific tests go here.
+--
+-- Purpose: Verify PG18 behavior that NOT NULL constraints are materialized
+--          as pg_constraint rows with contype = 'n' on both coordinator and
+--          worker shards. Also confirm our helper view (table_checks) does
+--          NOT surface NOT NULL entries.
+-- https://github.com/postgres/postgres/commit/14e87ffa5c543b5f30ead7413084c25f7735039f
+CREATE SCHEMA pg18_nn;
+SET search_path TO pg18_nn;
+-- Local control table
+DROP TABLE IF EXISTS nn_local CASCADE;
+NOTICE:  table "nn_local" does not exist, skipping
+CREATE TABLE nn_local(
+    a int NOT NULL,
+    b int,
+    c text NOT NULL
+);
+-- Distributed table
+DROP TABLE IF EXISTS nn_dist CASCADE;
+NOTICE:  table "nn_dist" does not exist, skipping
+CREATE TABLE nn_dist(
+    a int NOT NULL,
+    b int,
+    c text NOT NULL
+);
+SELECT create_distributed_table('nn_dist', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- Coordinator: count NOT NULL constraint rows
+SELECT 'local_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_local'::regclass
+GROUP BY contype
+ORDER BY contype;
+     label     | contype | count
+---------------------------------------------------------------------
+ local_n_count | n       |     2
+(1 row)
+
+SELECT 'dist_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_dist'::regclass
+GROUP BY contype
+ORDER BY contype;
+    label     | contype | count
+---------------------------------------------------------------------
+ dist_n_count | n       |     2
+(1 row)
+
+-- Our helper view should exclude NOT NULL
+SELECT 'table_checks_local_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_local'::regclass;
+          label           | count
+---------------------------------------------------------------------
+ table_checks_local_count |     0
+(1 row)
+
+SELECT 'table_checks_dist_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_dist'::regclass;
+          label          | count
+---------------------------------------------------------------------
+ table_checks_dist_count |     0
+(1 row)
+
+-- Add a real CHECK to ensure table_checks still reports real checks
+ALTER TABLE nn_dist ADD CONSTRAINT nn_dist_check CHECK (b IS DISTINCT FROM 42);
+SELECT 'table_checks_dist_with_real_check' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_dist'::regclass;
+               label               | count
+---------------------------------------------------------------------
+ table_checks_dist_with_real_check |     1
+(1 row)
+
+-- === Worker checks ===
+\c - - - :worker_1_port
+SET client_min_messages TO WARNING;
+SET search_path TO pg18_nn;
+-- Pick one heap shard of nn_dist in our schema
+SELECT format('%I.%I', n.nspname, c.relname) AS shard_regclass
+FROM pg_class c
+JOIN pg_namespace n ON n.oid = c.relnamespace
+WHERE n.nspname = 'pg18_nn'
+  AND c.relname LIKE 'nn_dist_%'
+  AND c.relkind = 'r'
+ORDER BY c.relname
+LIMIT 1
+\gset
+-- Expect: 2 NOT NULL rows (a,c) + 1 CHECK row on the shard
+SELECT 'worker_shard_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = :'shard_regclass'::regclass
+GROUP BY contype
+ORDER BY contype;
+        label         | contype | count
+---------------------------------------------------------------------
+ worker_shard_n_count | c       |     1
+ worker_shard_n_count | n       |     2
+(2 rows)
+
+-- table_checks on shard should hide NOT NULL
+SELECT 'table_checks_worker_shard_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = :'shard_regclass'::regclass;
+              label              | count
+---------------------------------------------------------------------
+ table_checks_worker_shard_count |     1
+(1 row)
+
+-- Drop one NOT NULL on coordinator; verify propagation
+\c - - - :master_port
+SET search_path TO pg18_nn;
+ALTER TABLE nn_dist ALTER COLUMN c DROP NOT NULL;
+-- Re-check on worker: NOT NULL count should drop to 1
+\c - - - :worker_1_port
+SET search_path TO pg18_nn;
+SELECT 'worker_shard_n_after_drop' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = :'shard_regclass'::regclass
+GROUP BY contype
+ORDER BY contype;
+           label           | contype | count
+---------------------------------------------------------------------
+ worker_shard_n_after_drop | c       |     1
+ worker_shard_n_after_drop | n       |     1
+(2 rows)
+
+-- And on coordinator
+\c - - - :master_port
+SET search_path TO pg18_nn;
+SELECT 'dist_n_after_drop' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_dist'::regclass
+GROUP BY contype
+ORDER BY contype;
+       label       | contype | count
+---------------------------------------------------------------------
+ dist_n_after_drop | c       |     1
+ dist_n_after_drop | n       |     1
+(2 rows)
+
+-- cleanup
+RESET client_min_messages;
+RESET search_path;
+DROP SCHEMA pg18_nn CASCADE;
+NOTICE:  drop cascades to 2 other objects
+DETAIL:  drop cascades to table pg18_nn.nn_local
+drop cascades to table pg18_nn.nn_dist

src/test/regress/expected/pg18_0.out

@@ -0,0 +1,14 @@
+--
+-- PG18
+--
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 18 AS server_version_ge_18
+\gset
+-- test invalid statistics
+-- behavior is same among PG versions, error message differs
+-- relevant PG18 commit: 3eea4dc2c7
+CREATE STATISTICS tst ON a FROM (VALUES (x)) AS foo;
+ERROR:  only a single relation is allowed in CREATE STATISTICS
+\if :server_version_ge_18
+\else
+\q

src/test/regress/multi_schedule

@@ -68,6 +68,7 @@ test: pg14
 test: pg15
 test: pg15_jsonpath detect_conn_close
 test: pg17 pg17_json
+test: pg18
 test: drop_column_partitioned_table
 test: tableam
 

src/test/regress/spec/isolation_merge.spec

@@ -5,18 +5,6 @@
 // create distributed tables to test behavior of MERGE in concurrent operations
 setup
 {
-	DO
-	$do$
-	DECLARE ver int;
-	BEGIN
-	  SELECT substring(version(), '\d+')::int into ver;
-	  IF (ver < 15)
-	  THEN
-	    RAISE EXCEPTION 'MERGE is not supported on PG versions below 15';
-	  END IF;
-	  END
-	$do$;
-
 	SET citus.shard_replication_factor TO 1;
 	SELECT 1 FROM master_add_node('localhost', 57637);
 	SELECT 1 FROM master_add_node('localhost', 57638);

src/test/regress/spec/isolation_merge_replicated.spec

@@ -5,18 +5,6 @@
 // create distributed tables to test behavior of MERGE in concurrent operations
 setup
 {
-	DO
-	$do$
-	DECLARE ver int;
-	BEGIN
-	  SELECT substring(version(), '\d+')::int into ver;
-	  IF (ver < 15)
-	  THEN
-	    RAISE EXCEPTION 'MERGE is not supported on PG versions below 15';
-	  END IF;
-	  END
-	$do$;
-
 	SET citus.shard_replication_factor TO 2;
 	SELECT 1 FROM master_add_node('localhost', 57637);
 	SELECT 1 FROM master_add_node('localhost', 57638);

src/test/regress/sql/merge_repartition2.sql

@@ -126,5 +126,128 @@ WHEN NOT MATCHED THEN
 
 SELECT compare_data();
 
-DROP SCHEMA merge_repartition2_schema CASCADE;
+---- https://github.com/citusdata/citus/issues/8180 ----
 
+CREATE TABLE dist_1 (a int, b int, c int);
+CREATE TABLE dist_2 (a int, b int, c int);
+CREATE TABLE dist_different_order_1 (b int, a int, c int);
+
+SELECT create_distributed_table('dist_1', 'a');
+SELECT create_distributed_table('dist_2', 'a');
+SELECT create_distributed_table('dist_different_order_1', 'a');
+
+MERGE INTO dist_1
+USING dist_2
+ON (dist_1.a = dist_2.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2.b;
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET b = src.b;
+
+MERGE INTO dist_different_order_1
+USING dist_1
+ON (dist_different_order_1.a = dist_1.b)
+WHEN MATCHED THEN UPDATE SET b = dist_1.b;
+
+CREATE TABLE dist_1_cast (a int, b int);
+CREATE TABLE dist_2_cast (a int, b numeric);
+
+SELECT create_distributed_table('dist_1_cast', 'a');
+SELECT create_distributed_table('dist_2_cast', 'a');
+
+MERGE INTO dist_1_cast
+USING dist_2_cast
+ON (dist_1_cast.a = dist_2_cast.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2_cast.b;
+
+MERGE INTO dist_1_cast
+USING (SELECT a, b::int as b FROM dist_2_cast) dist_2_cast
+ON (dist_1_cast.a = dist_2_cast.b)
+WHEN MATCHED THEN UPDATE SET b = dist_2_cast.b;
+
+-- a more sophisticated example
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+SELECT create_distributed_table('dist_source', 'tstamp_col');
+SELECT create_distributed_table('dist_target', 'int_col');
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+
+-- execute the query on distributed tables
+MERGE INTO dist_target target_alias
+USING dist_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+MERGE INTO local_target target_alias
+USING local_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+
+-- compare both targets
+
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+
+SET client_min_messages TO WARNING;
+DROP SCHEMA merge_repartition2_schema CASCADE;

src/test/regress/sql/multi_extension.sql

@@ -750,6 +750,16 @@ SELECT * FROM multi_extension.print_extension_changes();
 ALTER EXTENSION citus UPDATE TO '13.2-1';
 SELECT * FROM multi_extension.print_extension_changes();
 
+-- Test downgrade to 13.2-1 from 14.0-1
+ALTER EXTENSION citus UPDATE TO '14.0-1';
+ALTER EXTENSION citus UPDATE TO '13.2-1';
+-- Should be empty result since upgrade+downgrade should be a no-op
+SELECT * FROM multi_extension.print_extension_changes();
+
+-- Snapshot of state at 14.0-1
+ALTER EXTENSION citus UPDATE TO '14.0-1';
+SELECT * FROM multi_extension.print_extension_changes();
+
 DROP TABLE multi_extension.prev_objects, multi_extension.extension_diff;
 
 -- show running version

src/test/regress/sql/multi_modifications.sql

@@ -3,6 +3,7 @@ SET citus.next_shard_id TO 750000;
 SET citus.next_placement_id TO 750000;
 
 CREATE SCHEMA multi_modifications;
+SET search_path TO multi_modifications;
 
 -- some failure messages that comes from the worker nodes
 -- might change due to parallel executions, so suppress those
@@ -36,7 +37,7 @@ CREATE TABLE append_partitioned ( LIKE limit_orders );
 SET citus.shard_count TO 2;
 
 SELECT create_distributed_table('limit_orders', 'id', 'hash');
-SELECT create_distributed_table('multiple_hash', 'id', 'hash');
+SELECT create_distributed_table('multiple_hash', 'category', 'hash');
 SELECT create_distributed_table('range_partitioned', 'id', 'range');
 SELECT create_distributed_table('append_partitioned', 'id', 'append');
 
@@ -245,12 +246,14 @@ INSERT INTO limit_orders VALUES (275, 'ADR', 140, '2007-07-02 16:32:15', 'sell',
 
 -- First: Connect to the second worker node
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE limit_orders_750000 RENAME TO renamed_orders;
 
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 
 -- Fourth: Perform an INSERT on the remaining node
 -- the whole transaction should fail
@@ -259,6 +262,7 @@ INSERT INTO limit_orders VALUES (276, 'ADR', 140, '2007-07-02 16:32:15', 'sell',
 
 -- set the shard name back
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE renamed_orders RENAME TO limit_orders_750000;
@@ -266,12 +270,15 @@ ALTER TABLE renamed_orders RENAME TO limit_orders_750000;
 -- Verify the insert failed and both placements are healthy
 -- or the insert succeeded and placement marked unhealthy
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
 
 \c - - - :worker_2_port
+SET search_path TO multi_modifications;
 SELECT count(*) FROM limit_orders_750000 WHERE id = 276;
 
 \c - - - :master_port
+SET search_path TO multi_modifications;
 
 SELECT count(*) FROM limit_orders WHERE id = 276;
 
@@ -286,12 +293,14 @@ AND    s.logicalrelid = 'limit_orders'::regclass;
 
 -- First: Connect to the first worker node
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE limit_orders_750000 RENAME TO renamed_orders;
 
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 
 -- Fourth: Perform an INSERT on the remaining node
 \set VERBOSITY terse
@@ -312,12 +321,14 @@ AND    s.logicalrelid = 'limit_orders'::regclass;
 
 -- First: Connect to the first worker node
 \c - - - :worker_1_port
+SET search_path TO multi_modifications;
 
 -- Second: Move aside limit_orders shard on the second worker node
 ALTER TABLE renamed_orders RENAME TO limit_orders_750000;
 
 -- Third: Connect back to master node
 \c - - - :master_port
+SET search_path TO multi_modifications;
 
 -- attempting to change the partition key is unsupported
 UPDATE limit_orders SET id = 0 WHERE id = 246;
@@ -328,6 +339,375 @@ UPDATE limit_orders SET id = 246 WHERE id = 246;
 UPDATE limit_orders SET id = 246 WHERE id = 246 AND symbol = 'GM';
 UPDATE limit_orders SET id = limit_orders.id WHERE id = 246;
 
+CREATE TABLE dist_1 (a int, b int, c int);
+CREATE TABLE dist_2 (a int, b int, c int);
+CREATE TABLE dist_non_colocated (a int, b int, c int);
+CREATE TABLE dist_different_order_1 (b int, a int, c int);
+
+SELECT create_distributed_table('dist_1', 'a');
+SELECT create_distributed_table('dist_2', 'a');
+SELECT create_distributed_table('dist_non_colocated', 'a', colocate_with=>'none');
+SELECT create_distributed_table('dist_different_order_1', 'a');
+
+--
+-- https://github.com/citusdata/citus/issues/8087
+--
+
+---- update: should work ----
+
+-- setting shard key to itself --
+
+UPDATE dist_1 SET a = dist_1.a;
+UPDATE dist_1 SET a = dist_1.a WHERE dist_1.a > dist_1.b AND dist_1.b > 10;
+UPDATE dist_1 SET a = dist_1.a FROM dist_2 WHERE dist_1.a = dist_2.a;
+
+-- setting shard key to another var that's implied to be equal to shard key --
+
+UPDATE dist_1 SET a = b WHERE a = b;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a AND dist_1.b = dist_2.c AND (dist_2.c > 5 OR dist_2.c < 0);
+
+with cte as (
+select a, b from dist_1
+)
+update dist_1 set a = cte.a from cte where dist_1.a = cte.a;
+
+with cte as (
+select a as x, b as y from (select a, b from dist_1 limit 100) dt where b > 100
+)
+update dist_1 set a = cte.x from cte where dist_1.a = cte.x;
+
+with cte as (
+select d2.a as x, d1.b as y
+from dist_1 d1, dist_different_order_1 d2
+where d1.a=d2.a)
+update dist_1  set a = cte.x from cte where y != 0 and dist_1.a = cte.x;
+
+with cte as (
+select * from (select a as x, b as y from dist_2 limit 100) q
+)
+update dist_1 set a = cte.x from cte where b = cte.y and cte.y = a and a = cte.x;
+
+-- supported although the where clause will certainly eval to false
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a AND dist_1.a = 5 AND dist_2.a = 7;
+
+-- setting shard key to another var that's implied to be equal to shard key, repeat with dist_different_order_1 --
+
+UPDATE dist_1 SET a = dist_different_order_1.a FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a;
+
+-- test with extra quals
+UPDATE dist_1 SET a = dist_different_order_1.a FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a AND dist_1.b = dist_different_order_1.c AND (dist_different_order_1.c > 5 OR dist_different_order_1.c < 0);
+
+---- update: errors in router planner ----
+
+-- different column of the same relation, which is not implied to be equal to shard key --
+
+UPDATE dist_1 SET a = dist_1.b;
+
+-- another range table entry's column with the same attno, which is not implied to be equal to shard key --
+
+UPDATE dist_1 SET a = dist_2.a FROM dist_2;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a != dist_2.a;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a >= dist_2.a;
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.a OR dist_1.a > dist_2.a;
+UPDATE dist_1 SET a = dist_different_order_1.b FROM dist_different_order_1 WHERE dist_1.a = dist_different_order_1.a;
+
+UPDATE dist_1 SET a = foo.a FROM dist_1 foo;
+UPDATE dist_1 SET a = foo.a FROM dist_1 foo WHERE dist_1.a != foo.a;
+
+-- (*1) Would normally expect this to not throw an error because
+-- dist_1.a = dist_2.b AND dist_2.b = dist_2.a,
+-- so dist_1.a = dist_2.a, so we should be able to deduce
+-- that (dist_1.)a = dist_2.a, but seems predicate_implied_by()
+-- is not that smart.
+UPDATE dist_1 SET a = dist_2.a FROM dist_2 WHERE dist_1.a = dist_2.b AND dist_2.b = dist_2.a;
+
+-- and same here
+with cte as (
+select * from (select a as x, b as y from dist_different_order_1 limit 100) q
+)
+update dist_1 set a = cte.x from cte where a = cte.y and cte.y = b and b = cte.x;
+
+---- update: errors later (in logical or physical planner) ----
+
+-- setting shard key to itself --
+
+UPDATE dist_1 SET a = dist_1.a FROM dist_1 foo;
+UPDATE dist_1 SET a = dist_1.a FROM dist_2 foo;
+
+-- setting shard key to another var that's implied to be equal to shard key --
+
+UPDATE dist_1 SET a = dist_non_colocated.a FROM dist_non_colocated WHERE dist_1.a = dist_non_colocated.a;
+UPDATE dist_1 SET a = dist_2.b FROM dist_2 WHERE dist_1.a = dist_2.b;
+
+---- update: a more sophisticated example ----
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+SELECT create_distributed_table('dist_source', 'int_col');
+SELECT create_distributed_table('dist_target', 'int_col');
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+
+-- execute the query on distributed tables
+UPDATE dist_target target_alias
+SET int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+FROM dist_source source_alias
+WHERE target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col;
+
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+UPDATE local_target target_alias
+SET int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+FROM local_source source_alias
+WHERE target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col;
+
+-- compare both targets
+
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+
+---- merge: should work ----
+
+-- setting shard key to itself --
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.a;
+
+-- We don't care about action quals when deciding if the update
+-- could change the shard key, but still add some action quals for
+-- testing. See the comments written on top of the line we call
+-- TargetEntryChangesValue() in MergeQualAndTargetListFunctionsSupported().
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED AND dist_1.a > dist_1.b AND dist_1.b > 10 THEN UPDATE SET a = dist_1.a;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.a;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+-- setting shard key to another var that's implied to be equal to shard key --
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = dist_1.b)
+WHEN MATCHED THEN UPDATE SET a = dist_1.b;
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+-- test with extra quals
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b AND (dist_1.b > 1000 OR (dist_1.b < 500)))
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+-- setting shard key to another var that's implied to be equal to shard key, repeat with dist_different_order_1 --
+
+MERGE INTO dist_1
+USING dist_different_order_1 src
+ON (dist_1.a = src.a AND dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.b;
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+---- merge: errors in router planner ----
+
+-- different column of the same relation, which is not implied to be equal to shard key --
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.a)
+WHEN MATCHED THEN UPDATE SET a = dist_1.b;
+
+-- another range table entry's column with the same attno, which is not implied to be equal to shard key --
+
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+-- as in (*1), this is not supported
+MERGE INTO dist_1
+USING dist_1 src
+ON (dist_1.a = src.b AND src.b = src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (true)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+MERGE INTO dist_1
+USING dist_2 src
+ON (dist_1.a <= src.a)
+WHEN MATCHED THEN UPDATE SET a = src.a;
+
+---- merge: a more sophisticated example ----
+DROP TABLE dist_source, dist_target, local_source, local_target;
+CREATE TABLE dist_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE dist_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+CREATE TABLE local_source (tstamp_col timestamp, int_col int, text_arr_col text[], text_col text, json_col jsonb);
+CREATE TABLE local_target (text_col text, tstamp_col timestamp, json_col jsonb, text_arr_col text[], int_col int);
+
+SELECT create_distributed_table('dist_source', 'tstamp_col');
+SELECT create_distributed_table('dist_target', 'int_col');
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(1001, 2000) i;
+
+INSERT INTO dist_source (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[i::text, (i+1)::text, (i+2)::text],
+       'source_' || i,
+       ('{"a": ' || i || ', "b": ' || i+1 || '}')::jsonb
+FROM generate_series(901, 1000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1501, 2000) i;
+
+INSERT INTO dist_target (tstamp_col, int_col, text_arr_col, text_col, json_col)
+SELECT TIMESTAMP '2025-01-01 00:00:00' + (i || ' days')::interval,
+       i,
+       ARRAY[(i-1)::text, (i)::text, (i+1)::text],
+       'source_' || i-1,
+       ('{"a": ' || i*5 || ', "b": ' || i+20 || '}')::jsonb
+FROM generate_series(1401, 1500) i;
+
+INSERT INTO local_source SELECT * FROM dist_source;
+INSERT INTO local_target SELECT * FROM dist_target;
+
+-- execute the query on distributed tables
+MERGE INTO dist_target target_alias
+USING dist_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+
+-- execute the same query on local tables, everything is the same except table names behind the aliases
+MERGE INTO local_target target_alias
+USING local_source source_alias
+ON (target_alias.text_col = source_alias.text_col AND target_alias.int_col = source_alias.int_col)
+WHEN MATCHED THEN UPDATE SET
+    int_col = source_alias.int_col,
+    tstamp_col = source_alias.tstamp_col + interval '3 day',
+    text_arr_col = array_append(source_alias.text_arr_col, 'updated_' || source_alias.text_col),
+    json_col = ('{"a": "' || replace(source_alias.text_col, '"', '\"') || '"}')::jsonb,
+    text_col = source_alias.json_col->>'a'
+WHEN NOT MATCHED THEN
+  INSERT VALUES (source_alias.text_col, source_alias.tstamp_col, source_alias.json_col, source_alias.text_arr_col, source_alias.int_col );
+
+-- compare both targets
+
+SELECT COUNT(*) = 0 AS targets_match
+FROM (
+    SELECT * FROM dist_target
+    EXCEPT
+    SELECT * FROM local_target
+    UNION ALL
+    SELECT * FROM local_target
+    EXCEPT
+    SELECT * FROM dist_target
+) q;
+
 -- UPDATEs with a FROM clause are supported even with local tables
 UPDATE limit_orders SET limit_price = 0.00 FROM bidders
 					WHERE limit_orders.id = 246 AND
@@ -914,20 +1294,5 @@ DELETE FROM summary_table WHERE id < (
 CREATE TABLE multi_modifications.local (a int default 1, b int);
 INSERT INTO multi_modifications.local VALUES (default, (SELECT min(id) FROM summary_table));
 
-DROP TABLE insufficient_shards;
+SET client_min_messages TO WARNING;
-DROP TABLE raw_table;
-DROP TABLE summary_table;
-DROP TABLE reference_raw_table;
-DROP TABLE reference_summary_table;
-DROP TABLE limit_orders;
-DROP TABLE multiple_hash;
-DROP TABLE range_partitioned;
-DROP TABLE append_partitioned;
-DROP TABLE bidders;
-
-DROP FUNCTION stable_append;
-DROP FUNCTION immutable_append;
-DROP FUNCTION temp_strict_func;
-DROP TYPE order_side;
-
 DROP SCHEMA multi_modifications CASCADE;

src/test/regress/sql/multi_test_catalog_views.sql

@@ -71,15 +71,19 @@ SELECT "name" AS "Column",
 	   "relid"
 FROM table_attrs;
 
-CREATE VIEW table_checks AS
+CREATE OR REPLACE VIEW table_checks AS
-SELECT cc.constraint_name AS "Constraint",
+SELECT
-       ('CHECK ' || regexp_replace(check_clause, '^\((.*)\)$', '\1')) AS "Definition",
+  c.conname AS "Constraint",
-       format('%I.%I', ccu.table_schema, ccu.table_name)::regclass::oid AS relid
+  'CHECK ' ||
-FROM information_schema.check_constraints cc,
+  -- drop a single pair of outer parens if the deparser adds them
-     information_schema.constraint_column_usage ccu
+  regexp_replace(pg_get_expr(c.conbin, c.conrelid, true), '^\((.*)\)$', '\1')
-WHERE cc.constraint_schema = ccu.constraint_schema AND
+    AS "Definition",
-      cc.constraint_name = ccu.constraint_name
+  c.conrelid AS relid
-ORDER BY cc.constraint_name ASC;
+FROM pg_catalog.pg_constraint AS c
+WHERE c.contype <> 'n'         -- drop NOT NULL
+  AND c.conbin IS NOT NULL     -- only things with an expression (i.e., CHECKs)
+  AND c.conrelid <> 0          -- table-level (exclude domain checks)
+ORDER BY "Constraint", "Definition";
 
 CREATE VIEW index_attrs AS
 WITH indexoid AS (

src/test/regress/sql/pg18.sql

@@ -0,0 +1,134 @@
+--
+-- PG18
+--
+SHOW server_version \gset
+SELECT substring(:'server_version', '\d+')::int >= 18 AS server_version_ge_18
+\gset
+
+-- test invalid statistics
+-- behavior is same among PG versions, error message differs
+-- relevant PG18 commit: 3eea4dc2c7
+CREATE STATISTICS tst ON a FROM (VALUES (x)) AS foo;
+
+\if :server_version_ge_18
+\else
+\q
+\endif
+
+-- PG18-specific tests go here.
+--
+
+-- Purpose: Verify PG18 behavior that NOT NULL constraints are materialized
+--          as pg_constraint rows with contype = 'n' on both coordinator and
+--          worker shards. Also confirm our helper view (table_checks) does
+--          NOT surface NOT NULL entries.
+-- https://github.com/postgres/postgres/commit/14e87ffa5c543b5f30ead7413084c25f7735039f
+
+CREATE SCHEMA pg18_nn;
+SET search_path TO pg18_nn;
+
+-- Local control table
+DROP TABLE IF EXISTS nn_local CASCADE;
+CREATE TABLE nn_local(
+    a int NOT NULL,
+    b int,
+    c text NOT NULL
+);
+
+-- Distributed table
+DROP TABLE IF EXISTS nn_dist CASCADE;
+CREATE TABLE nn_dist(
+    a int NOT NULL,
+    b int,
+    c text NOT NULL
+);
+
+SELECT create_distributed_table('nn_dist', 'a');
+
+-- Coordinator: count NOT NULL constraint rows
+SELECT 'local_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_local'::regclass
+GROUP BY contype
+ORDER BY contype;
+
+SELECT 'dist_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_dist'::regclass
+GROUP BY contype
+ORDER BY contype;
+
+-- Our helper view should exclude NOT NULL
+SELECT 'table_checks_local_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_local'::regclass;
+
+SELECT 'table_checks_dist_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_dist'::regclass;
+
+-- Add a real CHECK to ensure table_checks still reports real checks
+ALTER TABLE nn_dist ADD CONSTRAINT nn_dist_check CHECK (b IS DISTINCT FROM 42);
+
+SELECT 'table_checks_dist_with_real_check' AS label, count(*)
+FROM public.table_checks
+WHERE relid = 'pg18_nn.nn_dist'::regclass;
+
+-- === Worker checks ===
+\c - - - :worker_1_port
+SET client_min_messages TO WARNING;
+SET search_path TO pg18_nn;
+
+-- Pick one heap shard of nn_dist in our schema
+SELECT format('%I.%I', n.nspname, c.relname) AS shard_regclass
+FROM pg_class c
+JOIN pg_namespace n ON n.oid = c.relnamespace
+WHERE n.nspname = 'pg18_nn'
+  AND c.relname LIKE 'nn_dist_%'
+  AND c.relkind = 'r'
+ORDER BY c.relname
+LIMIT 1
+\gset
+
+-- Expect: 2 NOT NULL rows (a,c) + 1 CHECK row on the shard
+SELECT 'worker_shard_n_count' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = :'shard_regclass'::regclass
+GROUP BY contype
+ORDER BY contype;
+
+-- table_checks on shard should hide NOT NULL
+SELECT 'table_checks_worker_shard_count' AS label, count(*)
+FROM public.table_checks
+WHERE relid = :'shard_regclass'::regclass;
+
+-- Drop one NOT NULL on coordinator; verify propagation
+\c - - - :master_port
+SET search_path TO pg18_nn;
+
+ALTER TABLE nn_dist ALTER COLUMN c DROP NOT NULL;
+
+-- Re-check on worker: NOT NULL count should drop to 1
+\c - - - :worker_1_port
+SET search_path TO pg18_nn;
+
+SELECT 'worker_shard_n_after_drop' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = :'shard_regclass'::regclass
+GROUP BY contype
+ORDER BY contype;
+
+-- And on coordinator
+\c - - - :master_port
+SET search_path TO pg18_nn;
+
+SELECT 'dist_n_after_drop' AS label, contype, count(*)
+FROM pg_constraint
+WHERE conrelid = 'pg18_nn.nn_dist'::regclass
+GROUP BY contype
+ORDER BY contype;
+
+-- cleanup
+RESET client_min_messages;
+RESET search_path;
+DROP SCHEMA pg18_nn CASCADE;