On Thu, Nov 28, 2019 at 5:49 PM Alvaro Herrera <alvhe...@2ndquadrant.com>
wrote:
> On 2019-Nov-28, Surafel Temesgen wrote:
>
> > On Thu, Nov 28, 2019 at 12:36 AM Alvaro Herrera <
> alvhe...@2ndquadrant.com>
> > wrote:
> >
> > > I think you should add a /* fall-though */ comment after changing
> state.
> > > Like this (this flow seems clearer; also DRY):
> > >
> > > if (!node->noCount &&
> > > node->position - node->offset >= node->count)
> > > {
> > > if (node->limitOption == LIMIT_OPTION_COUNT)
> > > {
> > > node->lstate = LIMIT_WINDOWEND;
> > > return NULL;
> > > }
> > > else
> > > {
> > > node->lstate = LIMIT_WINDOWEND_TIES;
> > > /* fall-through */
> > > }
> > > }
> > > else
> > > ...
> >
> > changed
>
> But you did not read my code snippet, did you ...?
>
I don't see it. changed to it and rebased to current master
regards
Surafel
From 944626bf7568604bd0a1b5785c6db009baf39d0c Mon Sep 17 00:00:00 2001
From: Surafel Temesgen <surafel3...@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
