fetch-first-with-ties-v15.patch

From 944626bf7568604bd0a1b5785c6db009baf39d0c Mon Sep 17 00:00:00 2001
From: Surafel Temesgen <surafel3000@gmail.com>
Date: Wed, 22 Jan 2020 09:10:59 +0300
Subject: [PATCH]  fetch first with ties

---
 doc/src/sgml/ref/select.sgml            |  15 ++-
 src/backend/catalog/sql_features.txt    |   2 +-
 src/backend/executor/nodeLimit.c        | 169 +++++++++++++++++++++---
 src/backend/nodes/copyfuncs.c           |   7 +
 src/backend/nodes/equalfuncs.c          |   2 +
 src/backend/nodes/outfuncs.c            |   7 +
 src/backend/nodes/readfuncs.c           |   6 +
 src/backend/optimizer/plan/createplan.c |  44 +++++-
 src/backend/optimizer/plan/planner.c    |   1 +
 src/backend/optimizer/util/pathnode.c   |   2 +
 src/backend/parser/analyze.c            |   3 +
 src/backend/parser/gram.y               | 117 ++++++++++++----
 src/backend/utils/adt/ruleutils.c       |  10 +-
 src/include/nodes/execnodes.h           |   4 +
 src/include/nodes/nodes.h               |  13 ++
 src/include/nodes/parsenodes.h          |   2 +
 src/include/nodes/pathnodes.h           |   1 +
 src/include/nodes/plannodes.h           |   5 +
 src/include/optimizer/pathnode.h        |   1 +
 src/include/optimizer/planmain.h        |   3 +-
 src/test/regress/expected/limit.out     | 104 +++++++++++++++
 src/test/regress/sql/limit.sql          |  31 +++++
 22 files changed, 489 insertions(+), 60 deletions(-)

diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 691e402803..2b11c38087 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -44,7 +44,7 @@ SELECT [ ALL | DISTINCT [ ON ( <replaceable class="parameter">expression</replac
     [ ORDER BY <replaceable class="parameter">expression</replaceable> [ ASC | DESC | USING <replaceable class="parameter">operator</replaceable> ] [ NULLS { FIRST | LAST } ] [, ...] ]
     [ LIMIT { <replaceable class="parameter">count</replaceable> | ALL } ]
     [ OFFSET <replaceable class="parameter">start</replaceable> [ ROW | ROWS ] ]
-    [ FETCH { FIRST | NEXT } [ <replaceable class="parameter">count</replaceable> ] { ROW | ROWS } ONLY ]
+    [ FETCH { FIRST | NEXT } [ <replaceable class="parameter">count</replaceable> ] { ROW | ROWS } { ONLY | WITH TIES } ]
     [ FOR { UPDATE | NO KEY UPDATE | SHARE | KEY SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT | SKIP LOCKED ] [...] ]
 
 <phrase>where <replaceable class="parameter">from_item</replaceable> can be one of:</phrase>
@@ -1438,7 +1438,7 @@ OFFSET <replaceable class="parameter">start</replaceable>
     which <productname>PostgreSQL</productname> also supports.  It is:
 <synopsis>
 OFFSET <replaceable class="parameter">start</replaceable> { ROW | ROWS }
-FETCH { FIRST | NEXT } [ <replaceable class="parameter">count</replaceable> ] { ROW | ROWS } ONLY
+FETCH { FIRST | NEXT } [ <replaceable class="parameter">count</replaceable> ] { ROW | ROWS } { ONLY | WITH TIES }
 </synopsis>
     In this syntax, the <replaceable class="parameter">start</replaceable>
     or <replaceable class="parameter">count</replaceable> value is required by
@@ -1448,10 +1448,13 @@ FETCH { FIRST | NEXT } [ <replaceable class="parameter">count</replaceable> ] {
     ambiguity.
     If <replaceable class="parameter">count</replaceable> is
     omitted in a <literal>FETCH</literal> clause, it defaults to 1.
-    <literal>ROW</literal>
-    and <literal>ROWS</literal> as well as <literal>FIRST</literal>
-    and <literal>NEXT</literal> are noise words that don't influence
-    the effects of these clauses.
+    The <literal>WITH TIES</literal> option is used to return any additional
+    rows that tie for the last place in the result set according to
+    <literal>ORDER BY</literal> clause; <literal>ORDER BY</literal>
+    is mandatory in this case.
+    <literal>ROW</literal> and <literal>ROWS</literal> as well as
+    <literal>FIRST</literal> and <literal>NEXT</literal> are noise
+    words that don't influence the effects of these clauses.
     According to the standard, the <literal>OFFSET</literal> clause must come
     before the <literal>FETCH</literal> clause if both are present; but
     <productname>PostgreSQL</productname> is laxer and allows either order.
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 9f840ddfd2..746c9a2516 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -345,7 +345,7 @@ F863	Nested <result offset clause> in <query expression>			YES
 F864	Top-level <result offset clause> in views			YES	
 F865	<offset row count> in <result offset clause>			YES	
 F866	FETCH FIRST clause: PERCENT option			NO	
-F867	FETCH FIRST clause: WITH TIES option			NO	
+F867	FETCH FIRST clause: WITH TIES option			YES	
 R010	Row pattern recognition: FROM clause			NO	
 R020	Row pattern recognition: WINDOW clause			NO	
 R030	Row pattern recognition: full aggregate support			NO	
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c
index d792e97cfa..00e986c027 100644
--- a/src/backend/executor/nodeLimit.c
+++ b/src/backend/executor/nodeLimit.c
@@ -41,6 +41,7 @@ static TupleTableSlot *			/* return: a tuple or NULL */
 ExecLimit(PlanState *pstate)
 {
 	LimitState *node = castNode(LimitState, pstate);
+	ExprContext *econtext = node->ps.ps_ExprContext;
 	ScanDirection direction;
 	TupleTableSlot *slot;
 	PlanState  *outerPlan;
@@ -102,6 +103,15 @@ ExecLimit(PlanState *pstate)
 					node->lstate = LIMIT_EMPTY;
 					return NULL;
 				}
+				/*
+				 * Tuple at limit is needed for comparation in subsequent execution
+				 * to detect ties.
+				 */
+				if (node->limitOption == LIMIT_OPTION_WITH_TIES &&
+					node->position - node->offset == node->count - 1)
+				{
+					ExecCopySlot(node->last_slot, slot);
+				}
 				node->subSlot = slot;
 				if (++node->position > node->offset)
 					break;
@@ -125,10 +135,12 @@ ExecLimit(PlanState *pstate)
 			if (ScanDirectionIsForward(direction))
 			{
 				/*
-				 * Forwards scan, so check for stepping off end of window. If
-				 * we are at the end of the window, return NULL without
-				 * advancing the subplan or the position variable; but change
-				 * the state machine state to record having done so.
+				 * Forwards scan, so check for stepping off end of window.  At
+				 * the end of the window, the behavior depends on whether WITH
+				 * TIES was specified: in that case, we need to change the state
+				 * machine to LIMIT_WINDOWTIES.If not (nothing was specified, or ONLY was)
+				 * return NULL without advancing the subplan or the position variable
+				 * but change the state machine to record having done so
 				 *
 				 * Once at the end, ideally, we can shut down parallel
 				 * resources but that would destroy the parallel context which
@@ -139,21 +151,42 @@ ExecLimit(PlanState *pstate)
 				if (!node->noCount &&
 					node->position - node->offset >= node->count)
 				{
-					node->lstate = LIMIT_WINDOWEND;
-					return NULL;
+					if (node->limitOption == LIMIT_OPTION_COUNT)
+					{
+						node->lstate = LIMIT_WINDOWEND;
+						return NULL;
+					}
+					else
+					{
+						node->lstate = LIMIT_WINDOWEND_TIES;
+						/* fall-through */
+					}
 				}
-
-				/*
-				 * Get next tuple from subplan, if any.
-				 */
-				slot = ExecProcNode(outerPlan);
-				if (TupIsNull(slot))
+				else
 				{
-					node->lstate = LIMIT_SUBPLANEOF;
-					return NULL;
+					/*
+					 * Get next tuple from subplan, if any.
+					 */
+					slot = ExecProcNode(outerPlan);
+					if (TupIsNull(slot))
+					{
+						node->lstate = LIMIT_SUBPLANEOF;
+						return NULL;
+					}
+
+					/*
+					 * Tuple at limit is needed for comparation in subsequent execution
+					 * to detect ties.
+					 */
+					if (node->limitOption == LIMIT_OPTION_WITH_TIES &&
+						node->position - node->offset == node->count - 1)
+					{
+						ExecCopySlot(node->last_slot, slot);
+					}
+					node->subSlot = slot;
+					node->position++;
+					break;
 				}
-				node->subSlot = slot;
-				node->position++;
 			}
 			else
 			{
@@ -175,6 +208,62 @@ ExecLimit(PlanState *pstate)
 					elog(ERROR, "LIMIT subplan failed to run backwards");
 				node->subSlot = slot;
 				node->position--;
+				break;
+			}
+
+		case LIMIT_WINDOWEND_TIES:
+			if (ScanDirectionIsForward(direction))
+			{
+				/*
+				 * Advance the subplan until we find the first row
+				 * with different ORDER BY pathkeys.
+				 */
+				slot = ExecProcNode(outerPlan);
+				if (TupIsNull(slot))
+				{
+					node->lstate = LIMIT_SUBPLANEOF;
+					return NULL;
+				}
+
+				/*
+				 * Test if the new tuple and the last tuple match.
+				 * If so we return the tuple.
+				 */
+				econtext->ecxt_innertuple = slot;
+				econtext->ecxt_outertuple = node->last_slot;
+				if (ExecQualAndReset(node->eqfunction, econtext))
+				{
+					node->subSlot = slot;
+					node->position++;
+				}
+				else
+				{
+					node->lstate = LIMIT_WINDOWEND;
+					return NULL;
+				}
+			}
+			else
+			{
+				/*
+				 * Backwards scan, so check for stepping off start of window.
+				 * Change only state-machine status if so.
+				 */
+				if (node->position <= node->offset + 1)
+				{
+					node->lstate = LIMIT_WINDOWSTART;
+					return NULL;
+				}
+
+				/*
+				 * Get previous tuple from subplan; there should be one !
+				 * And change state-machine status.
+				 */
+				slot = ExecProcNode(outerPlan);
+				if (TupIsNull(slot))
+					elog(ERROR, "LIMIT subplan failed to run backwards");
+				node->subSlot = slot;
+				node->position--;
+				node->lstate = LIMIT_INWINDOW;
 			}
 			break;
 
@@ -199,12 +288,27 @@ ExecLimit(PlanState *pstate)
 				return NULL;
 
 			/*
-			 * Backing up from window end: simply re-return the last tuple
-			 * fetched from the subplan.
+			 * We already past one position to detect ties so re-fetch previous tuple; there
+			 * should be one!  Note previous tuple must be in window.
 			 */
-			slot = node->subSlot;
-			node->lstate = LIMIT_INWINDOW;
-			/* position does not change 'cause we didn't advance it before */
+			if (node->limitOption == LIMIT_OPTION_WITH_TIES)
+			{
+				slot = ExecProcNode(outerPlan);
+				if (TupIsNull(slot))
+					elog(ERROR, "LIMIT subplan failed to run backwards");
+				node->subSlot = slot;
+				node->lstate = LIMIT_INWINDOW;
+			}
+			else
+			{
+				/*
+				 * Backing up from window end: simply re-return the last tuple
+				 * fetched from the subplan.
+				 */
+				slot = node->subSlot;
+				node->lstate = LIMIT_INWINDOW;
+				/* position does not change 'cause we didn't advance it before */
+			}
 			break;
 
 		case LIMIT_WINDOWSTART:
@@ -319,7 +423,7 @@ recompute_limits(LimitState *node)
 static int64
 compute_tuples_needed(LimitState *node)
 {
-	if (node->noCount)
+	if ((node->noCount) || (node->limitOption == LIMIT_OPTION_WITH_TIES))
 		return -1;
 	/* Note: if this overflows, we'll return a negative value, which is OK */
 	return node->count + node->offset;
@@ -372,6 +476,7 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
 										   (PlanState *) limitstate);
 	limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
 										  (PlanState *) limitstate);
+	limitstate->limitOption = node->limitOption;
 
 	/*
 	 * Initialize result type.
@@ -388,6 +493,26 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
 	 */
 	limitstate->ps.ps_ProjInfo = NULL;
 
+	/*
+	 * Initialize the equality evaluation, to detect ties.
+	 */
+	if (node->limitOption == LIMIT_OPTION_WITH_TIES)
+	{
+		TupleDesc	desc;
+		const TupleTableSlotOps *ops;
+
+		desc = ExecGetResultType(outerPlanState(limitstate));
+		ops = ExecGetResultSlotOps(outerPlanState(limitstate), NULL);
+
+		limitstate->last_slot = ExecInitExtraTupleSlot(estate, desc, ops);
+		limitstate->eqfunction = execTuplesMatchPrepare(desc,
+								   node->uniqNumCols,
+								   node->uniqColIdx,
+								   node->uniqOperators,
+								   node->uniqCollations,
+								   &limitstate->ps);
+	}
+
 	return limitstate;
 }
 
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 54ad62bb7f..557f0f83a8 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1150,6 +1150,11 @@ _copyLimit(const Limit *from)
 	 */
 	COPY_NODE_FIELD(limitOffset);
 	COPY_NODE_FIELD(limitCount);
+	COPY_SCALAR_FIELD(limitOption);
+	COPY_SCALAR_FIELD(uniqNumCols);
+	COPY_POINTER_FIELD(uniqColIdx, from->uniqNumCols * sizeof(AttrNumber));
+	COPY_POINTER_FIELD(uniqOperators, from->uniqNumCols * sizeof(Oid));
+	COPY_POINTER_FIELD(uniqCollations, from->uniqNumCols * sizeof(Oid));
 
 	return newnode;
 }
@@ -3043,6 +3048,7 @@ _copyQuery(const Query *from)
 	COPY_NODE_FIELD(sortClause);
 	COPY_NODE_FIELD(limitOffset);
 	COPY_NODE_FIELD(limitCount);
+	COPY_SCALAR_FIELD(limitOption);
 	COPY_NODE_FIELD(rowMarks);
 	COPY_NODE_FIELD(setOperations);
 	COPY_NODE_FIELD(constraintDeps);
@@ -3127,6 +3133,7 @@ _copySelectStmt(const SelectStmt *from)
 	COPY_NODE_FIELD(sortClause);
 	COPY_NODE_FIELD(limitOffset);
 	COPY_NODE_FIELD(limitCount);
+	COPY_SCALAR_FIELD(limitOption);
 	COPY_NODE_FIELD(lockingClause);
 	COPY_NODE_FIELD(withClause);
 	COPY_SCALAR_FIELD(op);
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 5b1ba143b1..3a613dc0b0 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -981,6 +981,7 @@ _equalQuery(const Query *a, const Query *b)
 	COMPARE_NODE_FIELD(sortClause);
 	COMPARE_NODE_FIELD(limitOffset);
 	COMPARE_NODE_FIELD(limitCount);
+	COMPARE_SCALAR_FIELD(limitOption);
 	COMPARE_NODE_FIELD(rowMarks);
 	COMPARE_NODE_FIELD(setOperations);
 	COMPARE_NODE_FIELD(constraintDeps);
@@ -1055,6 +1056,7 @@ _equalSelectStmt(const SelectStmt *a, const SelectStmt *b)
 	COMPARE_NODE_FIELD(sortClause);
 	COMPARE_NODE_FIELD(limitOffset);
 	COMPARE_NODE_FIELD(limitCount);
+	COMPARE_SCALAR_FIELD(limitOption);
 	COMPARE_NODE_FIELD(lockingClause);
 	COMPARE_NODE_FIELD(withClause);
 	COMPARE_SCALAR_FIELD(op);
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index d76fae44b8..f794708f84 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -914,6 +914,11 @@ _outLimit(StringInfo str, const Limit *node)
 
 	WRITE_NODE_FIELD(limitOffset);
 	WRITE_NODE_FIELD(limitCount);
+	WRITE_ENUM_FIELD(limitOption, LimitOption);
+	WRITE_INT_FIELD(uniqNumCols);
+	WRITE_ATTRNUMBER_ARRAY(uniqColIdx, node->uniqNumCols);
+	WRITE_OID_ARRAY(uniqOperators, node->uniqNumCols);
+	WRITE_OID_ARRAY(uniqCollations, node->uniqNumCols);
 }
 
 static void
@@ -2720,6 +2725,7 @@ _outSelectStmt(StringInfo str, const SelectStmt *node)
 	WRITE_NODE_FIELD(sortClause);
 	WRITE_NODE_FIELD(limitOffset);
 	WRITE_NODE_FIELD(limitCount);
+	WRITE_ENUM_FIELD(limitOption, LimitOption);
 	WRITE_NODE_FIELD(lockingClause);
 	WRITE_NODE_FIELD(withClause);
 	WRITE_ENUM_FIELD(op, SetOperation);
@@ -2930,6 +2936,7 @@ _outQuery(StringInfo str, const Query *node)
 	WRITE_NODE_FIELD(sortClause);
 	WRITE_NODE_FIELD(limitOffset);
 	WRITE_NODE_FIELD(limitCount);
+	WRITE_ENUM_FIELD(limitOption, LimitOption);
 	WRITE_NODE_FIELD(rowMarks);
 	WRITE_NODE_FIELD(setOperations);
 	WRITE_NODE_FIELD(constraintDeps);
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 551ce6c41c..2bbd7bc004 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -278,6 +278,7 @@ _readQuery(void)
 	READ_NODE_FIELD(sortClause);
 	READ_NODE_FIELD(limitOffset);
 	READ_NODE_FIELD(limitCount);
+	READ_ENUM_FIELD(limitOption, LimitOption);
 	READ_NODE_FIELD(rowMarks);
 	READ_NODE_FIELD(setOperations);
 	READ_NODE_FIELD(constraintDeps);
@@ -2370,6 +2371,11 @@ _readLimit(void)
 
 	READ_NODE_FIELD(limitOffset);
 	READ_NODE_FIELD(limitCount);
+	READ_ENUM_FIELD(limitOption, LimitOption);
+	READ_INT_FIELD(uniqNumCols);
+	READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->uniqNumCols);
+	READ_OID_ARRAY(uniqOperators, local_node->uniqNumCols);
+	READ_OID_ARRAY(uniqCollations, local_node->uniqNumCols);
 
 	READ_DONE();
 }
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index dff826a828..bda0ebb065 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -2335,7 +2335,9 @@ create_minmaxagg_plan(PlannerInfo *root, MinMaxAggPath *best_path)
 
 		plan = (Plan *) make_limit(plan,
 								   subparse->limitOffset,
-								   subparse->limitCount);
+								   subparse->limitCount,
+								   subparse->limitOption,
+								   0, NULL, NULL, NULL);
 
 		/* Must apply correct cost/width data to Limit node */
 		plan->startup_cost = mminfo->path->startup_cost;
@@ -2645,13 +2647,43 @@ create_limit_plan(PlannerInfo *root, LimitPath *best_path, int flags)
 {
 	Limit	   *plan;
 	Plan	   *subplan;
+	int			numUniqkeys = 0;
+	AttrNumber *uniqColIdx = NULL;
+	Oid		   *uniqOperators = NULL;
+	Oid		   *uniqCollations = NULL;
 
 	/* Limit doesn't project, so tlist requirements pass through */
 	subplan = create_plan_recurse(root, best_path->subpath, flags);
 
+	/* Extract information necessary for comparing rows for WITH TIES. */
+	if (best_path->limitOption == LIMIT_OPTION_WITH_TIES)
+	{
+		Query	   *parse = root->parse;
+		ListCell   *l;
+
+		numUniqkeys = list_length(parse->sortClause);
+		uniqColIdx = (AttrNumber *) palloc(numUniqkeys * sizeof(AttrNumber));
+		uniqOperators = (Oid *) palloc(numUniqkeys * sizeof(Oid));
+		uniqCollations = (Oid *) palloc(numUniqkeys * sizeof(Oid));
+
+		numUniqkeys = 0;
+		foreach(l, parse->sortClause)
+		{
+			SortGroupClause *sortcl = (SortGroupClause *) lfirst(l);
+			TargetEntry *tle = get_sortgroupclause_tle(sortcl, parse->targetList);
+
+			uniqColIdx[numUniqkeys] = tle->resno;
+			uniqOperators[numUniqkeys] = sortcl->eqop;
+			uniqCollations[numUniqkeys] = exprCollation((Node *) tle->expr);
+			numUniqkeys++;
+		}
+	}
+
 	plan = make_limit(subplan,
 					  best_path->limitOffset,
-					  best_path->limitCount);
+					  best_path->limitCount,
+					  best_path->limitOption,
+					  numUniqkeys, uniqColIdx, uniqOperators, uniqCollations);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -6554,7 +6586,8 @@ make_lockrows(Plan *lefttree, List *rowMarks, int epqParam)
  *	  Build a Limit plan node
  */
 Limit *
-make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount)
+make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount, LimitOption limitOption,
+			int uniqNumCols, AttrNumber *uniqColIdx, Oid *uniqOperators, Oid *uniqCollations)
 {
 	Limit	   *node = makeNode(Limit);
 	Plan	   *plan = &node->plan;
@@ -6566,6 +6599,11 @@ make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount)
 
 	node->limitOffset = limitOffset;
 	node->limitCount = limitCount;
+	node->limitOption = limitOption;
+	node->uniqNumCols = uniqNumCols;
+	node->uniqColIdx = uniqColIdx;
+	node->uniqOperators = uniqOperators;
+	node->uniqCollations = uniqCollations;
 
 	return node;
 }
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index d6f2153593..7db873949e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2320,6 +2320,7 @@ grouping_planner(PlannerInfo *root, bool inheritance_update,
 			path = (Path *) create_limit_path(root, final_rel, path,
 											  parse->limitOffset,
 											  parse->limitCount,
+											  parse->limitOption,
 											  offset_est, count_est);
 		}
 
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index e6d08aede5..73d03234fa 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -3545,6 +3545,7 @@ LimitPath *
 create_limit_path(PlannerInfo *root, RelOptInfo *rel,
 				  Path *subpath,
 				  Node *limitOffset, Node *limitCount,
+				  LimitOption limitOption,
 				  int64 offset_est, int64 count_est)
 {
 	LimitPath  *pathnode = makeNode(LimitPath);
@@ -3566,6 +3567,7 @@ create_limit_path(PlannerInfo *root, RelOptInfo *rel,
 	pathnode->subpath = subpath;
 	pathnode->limitOffset = limitOffset;
 	pathnode->limitCount = limitCount;
+	pathnode->limitOption = limitOption;
 
 	/*
 	 * Adjust the output rows count and costs according to the offset/limit.
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 748bebffc1..a16290bccd 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -1284,6 +1284,7 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 											EXPR_KIND_OFFSET, "OFFSET");
 	qry->limitCount = transformLimitClause(pstate, stmt->limitCount,
 										   EXPR_KIND_LIMIT, "LIMIT");
+	qry->limitOption = stmt->limitOption;
 
 	/* transform window clauses after we have seen all window functions */
 	qry->windowClause = transformWindowDefinitions(pstate,
@@ -1527,6 +1528,7 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 											EXPR_KIND_OFFSET, "OFFSET");
 	qry->limitCount = transformLimitClause(pstate, stmt->limitCount,
 										   EXPR_KIND_LIMIT, "LIMIT");
+	qry->limitOption = stmt->limitOption;
 
 	if (stmt->lockingClause)
 		ereport(ERROR,
@@ -1778,6 +1780,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 											EXPR_KIND_OFFSET, "OFFSET");
 	qry->limitCount = transformLimitClause(pstate, limitCount,
 										   EXPR_KIND_LIMIT, "LIMIT");
+	qry->limitOption = stmt->limitOption;
 
 	qry->rtable = pstate->p_rtable;
 	qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ba5916b4d2..8bbd92b569 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -127,6 +127,14 @@ typedef struct ImportQual
 	List	   *table_names;
 } ImportQual;
 
+/* Private struct for the result of opt_select_limit production */
+typedef struct SelectLimit
+{
+	Node *limitOffset;
+	Node *limitCount;
+	LimitOption limitOption;
+} SelectLimit;
+
 /* ConstraintAttributeSpec yields an integer bitmask of these flags: */
 #define CAS_NOT_DEFERRABLE			0x01
 #define CAS_DEFERRABLE				0x02
@@ -164,7 +172,7 @@ static List *makeOrderedSetArgs(List *directargs, List *orderedargs,
 								core_yyscan_t yyscanner);
 static void insertSelectOptions(SelectStmt *stmt,
 								List *sortClause, List *lockingClause,
-								Node *limitOffset, Node *limitCount,
+								SelectLimit *limitClause,
 								WithClause *withClause,
 								core_yyscan_t yyscanner);
 static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
@@ -242,6 +250,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	PartitionSpec		*partspec;
 	PartitionBoundSpec	*partboundspec;
 	RoleSpec			*rolespec;
+	struct SelectLimit	*selectlimit;
 }
 
 %type <node>	stmt schema_stmt
@@ -374,6 +383,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <ival>	import_qualification_type
 %type <importqual> import_qualification
 %type <node>	vacuum_relation
+%type <selectlimit> opt_select_limit select_limit limit_clause
 
 %type <list>	stmtblock stmtmulti
 				OptTableElementList TableElementList OptInherit definition
@@ -394,8 +404,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				target_list opt_target_list insert_column_list set_target_list
 				set_clause_list set_clause
 				def_list operator_def_list indirection opt_indirection
-				reloption_list group_clause TriggerFuncArgs select_limit
-				opt_select_limit opclass_item_list opclass_drop_list
+				reloption_list group_clause TriggerFuncArgs opclass_item_list opclass_drop_list
 				opclass_purpose opt_opfamily transaction_mode_list_or_empty
 				OptTableFuncElementList TableFuncElementList opt_type_modifiers
 				prep_type_clause
@@ -457,7 +466,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 				comment_type_any_name comment_type_name
 				security_label_type_any_name security_label_type_name
 
-%type <node>	fetch_args limit_clause select_limit_value
+%type <node>	fetch_args select_limit_value
 				offset_clause select_offset_value
 				select_fetch_first_value I_or_F_const
 %type <ival>	row_or_rows first_or_next
@@ -11337,14 +11346,14 @@ select_no_parens:
 			| select_clause sort_clause
 				{
 					insertSelectOptions((SelectStmt *) $1, $2, NIL,
-										NULL, NULL, NULL,
+										NULL, NULL,
 										yyscanner);
 					$$ = $1;
 				}
 			| select_clause opt_sort_clause for_locking_clause opt_select_limit
 				{
 					insertSelectOptions((SelectStmt *) $1, $2, $3,
-										list_nth($4, 0), list_nth($4, 1),
+										$4,
 										NULL,
 										yyscanner);
 					$$ = $1;
@@ -11352,7 +11361,7 @@ select_no_parens:
 			| select_clause opt_sort_clause select_limit opt_for_locking_clause
 				{
 					insertSelectOptions((SelectStmt *) $1, $2, $4,
-										list_nth($3, 0), list_nth($3, 1),
+										$3,
 										NULL,
 										yyscanner);
 					$$ = $1;
@@ -11360,7 +11369,7 @@ select_no_parens:
 			| with_clause select_clause
 				{
 					insertSelectOptions((SelectStmt *) $2, NULL, NIL,
-										NULL, NULL,
+										NULL,
 										$1,
 										yyscanner);
 					$$ = $2;
@@ -11368,7 +11377,7 @@ select_no_parens:
 			| with_clause select_clause sort_clause
 				{
 					insertSelectOptions((SelectStmt *) $2, $3, NIL,
-										NULL, NULL,
+										NULL,
 										$1,
 										yyscanner);
 					$$ = $2;
@@ -11376,7 +11385,7 @@ select_no_parens:
 			| with_clause select_clause opt_sort_clause for_locking_clause opt_select_limit
 				{
 					insertSelectOptions((SelectStmt *) $2, $3, $4,
-										list_nth($5, 0), list_nth($5, 1),
+										$5,
 										$1,
 										yyscanner);
 					$$ = $2;
@@ -11384,7 +11393,7 @@ select_no_parens:
 			| with_clause select_clause opt_sort_clause select_limit opt_for_locking_clause
 				{
 					insertSelectOptions((SelectStmt *) $2, $3, $5,
-										list_nth($4, 0), list_nth($4, 1),
+										$4,
 										$1,
 										yyscanner);
 					$$ = $2;
@@ -11678,20 +11687,44 @@ sortby:		a_expr USING qual_all_Op opt_nulls_order
 
 
 select_limit:
-			limit_clause offset_clause			{ $$ = list_make2($2, $1); }
-			| offset_clause limit_clause		{ $$ = list_make2($1, $2); }
-			| limit_clause						{ $$ = list_make2(NULL, $1); }
-			| offset_clause						{ $$ = list_make2($1, NULL); }
+			limit_clause offset_clause
+				{
+					$$ = $1;
+					($$)->limitOffset = $2;
+				}
+			| offset_clause limit_clause
+				{
+					$$ = $2;
+					($$)->limitOffset = $1;
+				}
+			| limit_clause
+				{
+					$$ = $1;
+				}
+			| offset_clause
+				{
+					SelectLimit *n = (SelectLimit *) palloc(sizeof(SelectLimit));
+					n->limitOffset = $1;
+					n->limitCount = NULL;
+					n->limitOption = LIMIT_OPTION_COUNT;
+					$$ = n;
+				}
 		;
 
 opt_select_limit:
 			select_limit						{ $$ = $1; }
-			| /* EMPTY */						{ $$ = list_make2(NULL,NULL); }
+			| /* EMPTY */						{ $$ = NULL; }
 		;
 
 limit_clause:
 			LIMIT select_limit_value
-				{ $$ = $2; }
+				{
+					SelectLimit *n = (SelectLimit *) palloc(sizeof(SelectLimit));
+					n->limitOffset = NULL;
+					n->limitCount = $2;
+					n->limitOption = LIMIT_OPTION_COUNT;
+					$$ = n;
+				}
 			| LIMIT select_limit_value ',' select_offset_value
 				{
 					/* Disabled because it was too confusing, bjm 2002-02-18 */
@@ -11709,9 +11742,29 @@ limit_clause:
 			 * we can see the ONLY token in the lookahead slot.
 			 */
 			| FETCH first_or_next select_fetch_first_value row_or_rows ONLY
-				{ $$ = $3; }
+				{
+					SelectLimit *n = (SelectLimit *) palloc(sizeof(SelectLimit));
+					n->limitOffset = NULL;
+					n->limitCount = $3;
+					n->limitOption = LIMIT_OPTION_COUNT;
+					$$ = n;
+				}
+			| FETCH first_or_next select_fetch_first_value row_or_rows WITH TIES
+				{
+					SelectLimit *n = (SelectLimit *) palloc(sizeof(SelectLimit));
+					n->limitOffset = NULL;
+					n->limitCount = $3;
+					n->limitOption = LIMIT_OPTION_WITH_TIES;
+					$$ = n;
+				}
 			| FETCH first_or_next row_or_rows ONLY
-				{ $$ = makeIntConst(1, -1); }
+				{
+					SelectLimit *n = (SelectLimit *) palloc(sizeof(SelectLimit));
+					n->limitOffset = NULL;
+					n->limitCount = makeIntConst(1, -1);
+					n->limitOption = LIMIT_OPTION_COUNT;
+					$$ = n;
+				}
 		;
 
 offset_clause:
@@ -15969,7 +16022,7 @@ makeOrderedSetArgs(List *directargs, List *orderedargs,
 static void
 insertSelectOptions(SelectStmt *stmt,
 					List *sortClause, List *lockingClause,
-					Node *limitOffset, Node *limitCount,
+					SelectLimit *limitClause,
 					WithClause *withClause,
 					core_yyscan_t yyscanner)
 {
@@ -15990,23 +16043,35 @@ insertSelectOptions(SelectStmt *stmt,
 	}
 	/* We can handle multiple locking clauses, though */
 	stmt->lockingClause = list_concat(stmt->lockingClause, lockingClause);
-	if (limitOffset)
+	if (limitClause && limitClause->limitOffset)
 	{
 		if (stmt->limitOffset)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("multiple OFFSET clauses not allowed"),
-					 parser_errposition(exprLocation(limitOffset))));
-		stmt->limitOffset = limitOffset;
+					 parser_errposition(exprLocation(limitClause->limitOffset))));
+		stmt->limitOffset = limitClause->limitOffset;
 	}
-	if (limitCount)
+	if (limitClause && limitClause->limitCount)
 	{
 		if (stmt->limitCount)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("multiple LIMIT clauses not allowed"),
-					 parser_errposition(exprLocation(limitCount))));
-		stmt->limitCount = limitCount;
+					 parser_errposition(exprLocation(limitClause->limitCount))));
+		stmt->limitCount = limitClause->limitCount;
+	}
+	if (limitClause && limitClause->limitOption != LIMIT_OPTION_DEFAULT)
+	{
+		if (stmt->limitOption)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("multiple limit options not allowed")));
+		if (!stmt->sortClause && limitClause->limitOption == LIMIT_OPTION_WITH_TIES)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("WITH TIES options can not be specified without ORDER BY clause")));
+		stmt->limitOption = limitClause->limitOption;
 	}
 	if (withClause)
 	{
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 116e00bce4..e8530344ac 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -5239,7 +5239,15 @@ get_select_query_def(Query *query, deparse_context *context,
 							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
 		get_rule_expr(query->limitOffset, context, false);
 	}
-	if (query->limitCount != NULL)
+	if (query->limitOption == LIMIT_OPTION_WITH_TIES)
+	{
+		appendContextKeyword(context, " FETCH FIRST ",
+							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
+		get_rule_expr(query->limitCount, context, false);
+		appendContextKeyword(context, " ROWS WITH TIES ",
+							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
+	}
+	if (query->limitCount != NULL && query->limitOption != LIMIT_OPTION_WITH_TIES)
 	{
 		appendContextKeyword(context, " LIMIT ",
 							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 1f6f5bbc20..237139eaab 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2343,6 +2343,7 @@ typedef enum
 	LIMIT_RESCAN,				/* rescan after recomputing parameters */
 	LIMIT_EMPTY,				/* there are no returnable rows */
 	LIMIT_INWINDOW,				/* have returned a row in the window */
+	LIMIT_WINDOWEND_TIES, 			/* have returned a tied row*/
 	LIMIT_SUBPLANEOF,			/* at EOF of subplan (within window) */
 	LIMIT_WINDOWEND,			/* stepped off end of window */
 	LIMIT_WINDOWSTART			/* stepped off beginning of window */
@@ -2353,12 +2354,15 @@ typedef struct LimitState
 	PlanState	ps;				/* its first field is NodeTag */
 	ExprState  *limitOffset;	/* OFFSET parameter, or NULL if none */
 	ExprState  *limitCount;		/* COUNT parameter, or NULL if none */
+	LimitOption	limitOption;	/* limit specification type */
 	int64		offset;			/* current OFFSET value */
 	int64		count;			/* current COUNT, if any */
 	bool		noCount;		/* if true, ignore count */
 	LimitStateCond lstate;		/* state machine status, as above */
 	int64		position;		/* 1-based index of last tuple returned */
 	TupleTableSlot *subSlot;	/* tuple last obtained from subplan */
+	ExprState  *eqfunction;		/* tuple equality qual in case of WITH TIES option */
+	TupleTableSlot *last_slot;	/* slot for evaluation of ties */
 } LimitState;
 
 #endif							/* EXECNODES_H */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index baced7eec0..0e6c0ad7b2 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -822,4 +822,17 @@ typedef enum OnConflictAction
 	ONCONFLICT_UPDATE			/* ON CONFLICT ... DO UPDATE */
 } OnConflictAction;
 
+/*
+ * LimitOption -
+ *	LIMIT option of query
+ *
+ * This is needed in both parsenodes.h and plannodes.h, so put it here...
+ */
+typedef enum LimitOption
+{
+	LIMIT_OPTION_COUNT,			/* FETCH FIRST... ONLY */
+	LIMIT_OPTION_WITH_TIES,		/* FETCH FIRST... WITH TIES */
+	LIMIT_OPTION_DEFAULT,		/* No limit present */
+} LimitOption;
+
 #endif							/* NODES_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index da0706add5..35f0292034 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -159,6 +159,7 @@ typedef struct Query
 
 	Node	   *limitOffset;	/* # of result tuples to skip (int8 expr) */
 	Node	   *limitCount;		/* # of result tuples to return (int8 expr) */
+	LimitOption	limitOption;	/* limit type { WITH TIES | ONLY } */
 
 	List	   *rowMarks;		/* a list of RowMarkClause's */
 
@@ -1616,6 +1617,7 @@ typedef struct SelectStmt
 	List	   *sortClause;		/* sort clause (a list of SortBy's) */
 	Node	   *limitOffset;	/* # of result tuples to skip */
 	Node	   *limitCount;		/* # of result tuples to return */
+	LimitOption	limitOption;	/* limit type */
 	List	   *lockingClause;	/* FOR UPDATE (list of LockingClause's) */
 	WithClause *withClause;		/* WITH clause */
 
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 3d3be197e0..84bd9efccc 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1795,6 +1795,7 @@ typedef struct LimitPath
 	Path	   *subpath;		/* path representing input source */
 	Node	   *limitOffset;	/* OFFSET parameter, or NULL if none */
 	Node	   *limitCount;		/* COUNT parameter, or NULL if none */
+	LimitOption	limitOption;	/* FETCH FIRST with ties or exact number */
 } LimitPath;
 
 
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 32c0d87f80..9fa33a58b5 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -971,6 +971,11 @@ typedef struct Limit
 	Plan		plan;
 	Node	   *limitOffset;	/* OFFSET parameter, or NULL if none */
 	Node	   *limitCount;		/* COUNT parameter, or NULL if none */
+	LimitOption	limitOption;	/* fetch first with ties or exact number */
+	int			uniqNumCols;		/* number of columns to check for similarity  */
+	AttrNumber *uniqColIdx;		/* their indexes in the target list */
+	Oid		   *uniqOperators;	/* equality operators to compare with */
+	Oid		   *uniqCollations;	/* collations for equality comparisons */
 } Limit;
 
 
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index e450fe112a..5dd6f41ad4 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -262,6 +262,7 @@ extern ModifyTablePath *create_modifytable_path(PlannerInfo *root,
 extern LimitPath *create_limit_path(PlannerInfo *root, RelOptInfo *rel,
 									Path *subpath,
 									Node *limitOffset, Node *limitCount,
+									LimitOption limitOption,
 									int64 offset_est, int64 count_est);
 extern void adjust_limit_rows_costs(double *rows,
 									Cost *startup_cost, Cost *total_cost,
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index eab486a621..5f71993ab7 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -56,7 +56,8 @@ extern Agg *make_agg(List *tlist, List *qual,
 					 int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
 					 List *groupingSets, List *chain,
 					 double dNumGroups, Plan *lefttree);
-extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount);
+extern Limit *make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount,
+		 LimitOption limitOption,int uniqNumCols, AttrNumber *uniqColIdx, Oid *uniqOperators, Oid *uniqCollations);
 
 /*
  * prototypes for plan/initsplan.c
diff --git a/src/test/regress/expected/limit.out b/src/test/regress/expected/limit.out
index c18f547cbd..e2699f05da 100644
--- a/src/test/regress/expected/limit.out
+++ b/src/test/regress/expected/limit.out
@@ -286,6 +286,58 @@ fetch all in c4;
 ----+----
 (0 rows)
 
+declare c5 cursor for select * from int8_tbl order by q1 fetch first 2 rows with ties;
+fetch all in c5;
+ q1  |        q2        
+-----+------------------
+ 123 |              456
+ 123 | 4567890123456789
+(2 rows)
+
+fetch 1 in c5;
+ q1 | q2 
+----+----
+(0 rows)
+
+fetch backward 1 in c5;
+ q1  |        q2        
+-----+------------------
+ 123 | 4567890123456789
+(1 row)
+
+fetch backward 1 in c5;
+ q1  | q2  
+-----+-----
+ 123 | 456
+(1 row)
+
+fetch all in c5;
+ q1  |        q2        
+-----+------------------
+ 123 | 4567890123456789
+(1 row)
+
+fetch backward all in c5;
+ q1  |        q2        
+-----+------------------
+ 123 | 4567890123456789
+ 123 |              456
+(2 rows)
+
+fetch all in c5;
+ q1  |        q2        
+-----+------------------
+ 123 |              456
+ 123 | 4567890123456789
+(2 rows)
+
+fetch backward all in c5;
+ q1  |        q2        
+-----+------------------
+ 123 | 4567890123456789
+ 123 |              456
+(2 rows)
+
 rollback;
 -- Stress test for variable LIMIT in conjunction with bounded-heap sorting
 SELECT
@@ -503,3 +555,55 @@ select sum(tenthous) as s1, sum(tenthous) + random()*0 as s2
  45020 | 45020
 (3 rows)
 
+--
+-- FETCH FIRST
+-- Check the WITH TIES clause
+--
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 2 ROW WITH TIES;
+ thousand 
+----------
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+(10 rows)
+
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 1 ROW WITH TIES;
+ thousand 
+----------
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+        0
+(10 rows)
+
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 2 ROW ONLY;
+ thousand 
+----------
+        0
+        0
+(2 rows)
+
+-- should fail
+SELECT ''::text AS two, unique1, unique2, stringu1
+		FROM onek WHERE unique1 > 50
+		FETCH FIRST 2 ROW WITH TIES;
+ERROR:  WITH TIES options can not be specified without ORDER BY clause
diff --git a/src/test/regress/sql/limit.sql b/src/test/regress/sql/limit.sql
index 2a313d80ca..4d129f7794 100644
--- a/src/test/regress/sql/limit.sql
+++ b/src/test/regress/sql/limit.sql
@@ -71,6 +71,16 @@ fetch backward all in c4;
 fetch backward 1 in c4;
 fetch all in c4;
 
+declare c5 cursor for select * from int8_tbl order by q1 fetch first 2 rows with ties;
+fetch all in c5;
+fetch 1 in c5;
+fetch backward 1 in c5;
+fetch backward 1 in c5;
+fetch all in c5;
+fetch backward all in c5;
+fetch all in c5;
+fetch backward all in c5;
+
 rollback;
 
 -- Stress test for variable LIMIT in conjunction with bounded-heap sorting
@@ -141,3 +151,24 @@ select sum(tenthous) as s1, sum(tenthous) + random()*0 as s2
 
 select sum(tenthous) as s1, sum(tenthous) + random()*0 as s2
   from tenk1 group by thousand order by thousand limit 3;
+
+--
+-- FETCH FIRST
+-- Check the WITH TIES clause
+--
+
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 2 ROW WITH TIES;
+
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 1 ROW WITH TIES;
+
+SELECT  thousand
+		FROM onek WHERE thousand < 5
+		ORDER BY thousand FETCH FIRST 2 ROW ONLY;
+-- should fail
+SELECT ''::text AS two, unique1, unique2, stringu1
+		FROM onek WHERE unique1 > 50
+		FETCH FIRST 2 ROW WITH TIES;
-- 
2.17.1