On Tue, Jan 15, 2019 at 2:51 PM Tomas Vondra <tomas.von...@2ndquadrant.com>
wrote:
> What do you mean by "raw statistic"?
>
I mean without further calculation to consider other operation
>
> IMHO the best thing you can do is call estimate_num_groups() and combine
> that with the number of input rows. That shall benefit from ndistinct
> coefficients when available, etc. I've been thinking that considering
> the unreliability of grouping estimates we should use a multiple of the
> average size (because there may be much larger groups), but I think
> that's quite unprecipled and I'd much rather try without it first.
>
>
thank you for clarifying.
The attache patch use your suggestion uptread
regards
Surafel
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 4db8142afa..ed7249daeb 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>
@@ -1397,7 +1397,7 @@ 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
@@ -1407,7 +1407,10 @@ 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>
+ <literal>ROW</literal> .
+ <literal>WITH TIES</literal> option is used to return two or more rows
+ that tie for last place in the limit results set according to <literal>ORDER BY</literal>
+ clause (<literal>ORDER BY</literal> clause must be specified in this case).
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.
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c
index baa669abe8..5e7790c0d6 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;
@@ -131,7 +132,8 @@ ExecLimit(PlanState *pstate)
* the state machine state to record having done so.
*/
if (!node->noCount &&
- node->position - node->offset >= node->count)
+ node->position - node->offset >= node->count &&
+ node->limitOption == WITH_ONLY)
{
node->lstate = LIMIT_WINDOWEND;
@@ -145,17 +147,64 @@ ExecLimit(PlanState *pstate)
return NULL;
}
- /*
- * Get next tuple from subplan, if any.
- */
- slot = ExecProcNode(outerPlan);
- if (TupIsNull(slot))
+ else if (!node->noCount &&
+ node->position - node->offset >= node->count &&
+ node->limitOption == WITH_TIES)
{
- 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;
+ }
+ /*
+ * 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))
+ {
+ ExecCopySlot(node->last_slot, slot);
+ node->subSlot = slot;
+ node->position++;
+ }
+ else
+ {
+ node->lstate = LIMIT_WINDOWEND;
+
+ /*
+ * If we know we won't need to back up, we can release
+ * resources at this point.
+ */
+ if (!(node->ps.state->es_top_eflags & EXEC_FLAG_BACKWARD))
+ (void) ExecShutdownNode(outerPlan);
+
+ return NULL;
+ }
+
+ }
+ else
+ {
+ /*
+ * Get next tuple from subplan, if any.
+ */
+ slot = ExecProcNode(outerPlan);
+ if (TupIsNull(slot))
+ {
+ node->lstate = LIMIT_SUBPLANEOF;
+ return NULL;
+ }
+ if (node->limitOption == WITH_TIES)
+ {
+ ExecCopySlot(node->last_slot, slot);
+ }
+ node->subSlot = slot;
+ node->position++;
}
- node->subSlot = slot;
- node->position++;
}
else
{
@@ -311,7 +360,8 @@ recompute_limits(LimitState *node)
* must update the child node anyway, in case this is a rescan and the
* previous time we got a different result.
*/
- ExecSetTupleBound(compute_tuples_needed(node), outerPlanState(node));
+ if(node->limitOption == WITH_ONLY)
+ ExecSetTupleBound(compute_tuples_needed(node), outerPlanState(node));
}
/*
@@ -374,6 +424,7 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
(PlanState *) limitstate);
limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
(PlanState *) limitstate);
+ limitstate->limitOption = node->limitOption;
/*
* Initialize result type.
@@ -390,6 +441,24 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
*/
limitstate->ps.ps_ProjInfo = NULL;
+ /*
+ * Initialize the equality evaluation, to detect ties.
+ */
+ if (node->limitOption == WITH_TIES)
+ {
+ TupleDesc scanDesc;
+ const TupleTableSlotOps *ops;
+ scanDesc = limitstate->ps.ps_ResultTupleDesc;
+ ops = ExecGetResultSlotOps(outerPlanState(limitstate), NULL);
+ limitstate->last_slot = ExecInitExtraTupleSlot(estate, scanDesc, ops);
+ limitstate->eqfunction =
+ execTuplesMatchPrepare(ExecGetResultType(outerPlanState(limitstate)),
+ node->numCols,
+ node->uniqColIdx,
+ node->uniqOperators,
+ &limitstate->ps);
+ }
+
return limitstate;
}
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 006a3d1772..56131af6bf 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1136,6 +1136,10 @@ _copyLimit(const Limit *from)
*/
COPY_NODE_FIELD(limitOffset);
COPY_NODE_FIELD(limitCount);
+ COPY_SCALAR_FIELD(limitOption);
+ COPY_SCALAR_FIELD(numCols);
+ COPY_POINTER_FIELD(uniqColIdx, from->numCols * sizeof(AttrNumber));
+ COPY_POINTER_FIELD(uniqOperators, from->numCols * sizeof(Oid));
return newnode;
}
@@ -3021,6 +3025,7 @@ _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);
@@ -3105,6 +3110,7 @@ _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 133df1b364..5bad7cdbf8 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -974,6 +974,7 @@ _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);
@@ -1048,6 +1049,7 @@ _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 0fde876c77..85827e31ef 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -894,12 +894,34 @@ _outLockRows(StringInfo str, const LockRows *node)
static void
_outLimit(StringInfo str, const Limit *node)
{
+ int i;
WRITE_NODE_TYPE("LIMIT");
_outPlanInfo(str, (const Plan *) node);
WRITE_NODE_FIELD(limitOffset);
WRITE_NODE_FIELD(limitCount);
+ WRITE_ENUM_FIELD(limitOption, LimitOption);
+ WRITE_INT_FIELD(numCols);
+ if (node->numCols > 0)
+ {
+ appendStringInfoString(str, " :uniqColIdx");
+ for (i = 0; i < node->numCols; i++)
+ appendStringInfo(str, " %d", node->uniqColIdx[i]);
+
+ appendStringInfoString(str, " :uniqOperators");
+ for (i = 0; i < node->numCols; i++)
+ appendStringInfo(str, " %u", node->uniqOperators[i]);
+ }
+ else
+ {
+ appendStringInfoString(str, " :uniqColIdx");
+ appendStringInfo(str, " NULL");
+
+ appendStringInfoString(str, " :uniqOperators");
+ appendStringInfo(str, " NULL");
+ }
+
}
static void
@@ -2680,6 +2702,7 @@ _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);
@@ -2889,6 +2912,7 @@ _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 ec6f2569ab..7c7d1ecf15 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);
@@ -2320,6 +2321,10 @@ _readLimit(void)
READ_NODE_FIELD(limitOffset);
READ_NODE_FIELD(limitCount);
+ READ_ENUM_FIELD(limitOption, LimitOption);
+ READ_INT_FIELD(numCols);
+ READ_ATTRNUMBER_ARRAY(uniqColIdx, local_node->numCols);
+ READ_OID_ARRAY(uniqOperators, local_node->numCols);
READ_DONE();
}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 97d0c28132..80a22c715d 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -2155,7 +2155,9 @@ create_minmaxagg_plan(PlannerInfo *root, MinMaxAggPath *best_path)
plan = (Plan *) make_limit(plan,
subparse->limitOffset,
- subparse->limitCount);
+ subparse->limitCount,
+ subparse->limitOption,
+ 0, NULL, NULL);
/* Must apply correct cost/width data to Limit node */
plan->startup_cost = mminfo->path->startup_cost;
@@ -2454,13 +2456,40 @@ create_limit_plan(PlannerInfo *root, LimitPath *best_path, int flags)
{
Limit *plan;
Plan *subplan;
+ int numsortkeys = 0;
+ AttrNumber *sortColIdx = NULL;
+ Oid *sortOperators = NULL;
/* Limit doesn't project, so tlist requirements pass through */
subplan = create_plan_recurse(root, best_path->subpath, flags);
+ if (best_path->limitOption == WITH_TIES)
+ {
+ Query *parse = root->parse;
+ ListCell *l;
+
+ numsortkeys = list_length(parse->sortClause);
+ sortColIdx = (AttrNumber *) palloc(numsortkeys * sizeof(AttrNumber));
+ sortOperators = (Oid *) palloc(numsortkeys * sizeof(Oid));
+
+ numsortkeys = 0;
+ foreach(l, parse->sortClause)
+ {
+ SortGroupClause *sortcl = (SortGroupClause *) lfirst(l);
+ TargetEntry *tle = get_sortgroupclause_tle(sortcl, parse->targetList);
+
+ sortColIdx[numsortkeys] = tle->resno;
+ sortOperators[numsortkeys] = sortcl->eqop;
+ numsortkeys++;
+ }
+
+ }
+
plan = make_limit(subplan,
best_path->limitOffset,
- best_path->limitCount);
+ best_path->limitCount,
+ best_path->limitOption,
+ numsortkeys, sortColIdx, sortOperators);
copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -6325,7 +6354,8 @@ 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 ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators)
{
Limit *node = makeNode(Limit);
Plan *plan = &node->plan;
@@ -6337,6 +6367,10 @@ make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount)
node->limitOffset = limitOffset;
node->limitCount = limitCount;
+ node->limitOption = limitOption;
+ node->numCols = ordNumCols;
+ node->uniqColIdx = ordColIdx;
+ node->uniqOperators = ordOperators;
return node;
}
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 5ba612922f..573c198395 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2145,6 +2145,7 @@ 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 b2637d0e89..17695dedfb 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -3411,6 +3411,7 @@ 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);
@@ -3432,6 +3433,7 @@ 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.
@@ -3473,6 +3475,20 @@ create_limit_path(PlannerInfo *root, RelOptInfo *rel,
count_rows = (double) count_est;
else
count_rows = clamp_row_est(subpath->rows * 0.10);
+ if (limitOption == WITH_TIES)
+ {
+ double numGroups;
+ double avgGroupSize;
+ List *groupExprs;
+
+ groupExprs = get_sortgrouplist_exprs(root->parse->sortClause,
+ root->parse->targetList);
+
+ numGroups = estimate_num_groups(root, groupExprs, subpath->rows,
+ NULL);
+ avgGroupSize = subpath->rows / numGroups;
+ count_rows = Max(avgGroupSize, count_est + (avgGroupSize/2));
+ }
if (count_rows > pathnode->path.rows)
count_rows = pathnode->path.rows;
if (subpath->rows > 0)
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 5ff6964d51..da0262a730 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -1302,6 +1302,7 @@ 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,
@@ -1548,6 +1549,7 @@ 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,
@@ -1783,6 +1785,7 @@ 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 c086235b25..8428516cb8 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -164,6 +164,7 @@ static List *makeOrderedSetArgs(List *directargs, List *orderedargs,
static void insertSelectOptions(SelectStmt *stmt,
List *sortClause, List *lockingClause,
Node *limitOffset, Node *limitCount,
+ void *limitOption,
WithClause *withClause,
core_yyscan_t yyscanner);
static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
@@ -387,7 +388,7 @@ 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
+ reloption_list group_clause TriggerFuncArgs select_limit limit_clause
opt_select_limit opclass_item_list opclass_drop_list
opclass_purpose opt_opfamily transaction_mode_list_or_empty
OptTableFuncElementList TableFuncElementList opt_type_modifiers
@@ -449,7 +450,7 @@ 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
@@ -11183,7 +11184,7 @@ select_no_parens:
| select_clause sort_clause
{
insertSelectOptions((SelectStmt *) $1, $2, NIL,
- NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
yyscanner);
$$ = $1;
}
@@ -11191,6 +11192,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $1, $2, $3,
list_nth($4, 0), list_nth($4, 1),
+ (list_nth($4, 2)),
NULL,
yyscanner);
$$ = $1;
@@ -11199,6 +11201,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $1, $2, $4,
list_nth($3, 0), list_nth($3, 1),
+ (list_nth($3, 2)),
NULL,
yyscanner);
$$ = $1;
@@ -11207,7 +11210,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, NULL, NIL,
NULL, NULL,
- $1,
+ NULL,$1,
yyscanner);
$$ = $2;
}
@@ -11215,7 +11218,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, NIL,
NULL, NULL,
- $1,
+ NULL,$1,
yyscanner);
$$ = $2;
}
@@ -11223,6 +11226,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, $4,
list_nth($5, 0), list_nth($5, 1),
+ list_nth($5, 2),
$1,
yyscanner);
$$ = $2;
@@ -11231,6 +11235,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, $5,
list_nth($4, 0), list_nth($4, 1),
+ list_nth($4, 2),
$1,
yyscanner);
$$ = $2;
@@ -11517,20 +11522,20 @@ sortby: a_expr USING qual_all_Op opt_nulls_order
select_limit:
- limit_clause offset_clause { $$ = list_make2($2, $1); }
- | offset_clause limit_clause { $$ = list_make2($1, $2); }
- | limit_clause { $$ = list_make2(NULL, $1); }
- | offset_clause { $$ = list_make2($1, NULL); }
+ limit_clause offset_clause { $$ = list_make3($2, list_nth($1, 0), list_nth($1, 1)); }
+ | offset_clause limit_clause { $$ = list_make3($1, list_nth($2, 0), list_nth($2, 1)); }
+ | limit_clause { $$ = list_make3(NULL, list_nth($1, 0), list_nth($1, 1)); }
+ | offset_clause { $$ = list_make3($1, NULL, NULL); }
;
opt_select_limit:
select_limit { $$ = $1; }
- | /* EMPTY */ { $$ = list_make2(NULL,NULL); }
+ | /* EMPTY */ { $$ = list_make3(NULL, NULL, NULL); }
;
limit_clause:
LIMIT select_limit_value
- { $$ = $2; }
+ { $$ = list_make2($2, NULL); }
| LIMIT select_limit_value ',' select_offset_value
{
/* Disabled because it was too confusing, bjm 2002-02-18 */
@@ -11548,9 +11553,11 @@ limit_clause:
* we can see the ONLY token in the lookahead slot.
*/
| FETCH first_or_next select_fetch_first_value row_or_rows ONLY
- { $$ = $3; }
+ { $$ = list_make2($3, makeString("WITH_ONLY")); }
+ | FETCH first_or_next select_fetch_first_value row_or_rows WITH TIES
+ { $$ = list_make2($3, makeString("WITH_TIES")); }
| FETCH first_or_next row_or_rows ONLY
- { $$ = makeIntConst(1, -1); }
+ { $$ = list_make2(makeIntConst(1, -1), NULL); }
;
offset_clause:
@@ -15800,6 +15807,7 @@ static void
insertSelectOptions(SelectStmt *stmt,
List *sortClause, List *lockingClause,
Node *limitOffset, Node *limitCount,
+ void *limitOption,
WithClause *withClause,
core_yyscan_t yyscanner)
{
@@ -15838,6 +15846,21 @@ insertSelectOptions(SelectStmt *stmt,
parser_errposition(exprLocation(limitCount))));
stmt->limitCount = limitCount;
}
+ if (limitOption)
+ {
+ if (stmt->limitOption)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("multiple limit options not allowed")));
+ if (!stmt->sortClause && strcmp(strVal(limitOption), "WITH_TIES") == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_SYNTAX_ERROR),
+ errmsg("WITH TIES options can not be specified without ORDER BY clause")));
+ if (strcmp(strVal(limitOption), "WITH_ONLY") == 0)
+ stmt->limitOption = WITH_ONLY;
+ else
+ stmt->limitOption = WITH_TIES;
+ }
if (withClause)
{
if (stmt->withClause)
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 7cae085177..c432e16324 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2287,12 +2287,15 @@ 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 10dac60cd3..bbf2a44180 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -814,4 +814,16 @@ 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
+{
+ WITH_ONLY, /* FETCH FIRST... ONLY */
+ WITH_TIES /* FETCH FIRST... WITH TIES */
+} LimitOption;
+
#endif /* NODES_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 27782fed6c..2d0c1f8c55 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 | WITH ONLY] */
List *rowMarks; /* a list of RowMarkClause's */
@@ -1572,6 +1573,7 @@ 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/plannodes.h b/src/include/nodes/plannodes.h
index 6d087c268f..48eba08374 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -946,6 +946,10 @@ 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 numCols; /* number of columns to check for Similarity */
+ AttrNumber *uniqColIdx; /* their indexes in the target list */
+ Oid *uniqOperators; /* equality operators to compare with */
} Limit;
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 3430061361..44a60598f3 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1737,6 +1737,7 @@ 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/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index bd905d3328..303501a14c 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -248,6 +248,7 @@ 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 Path *reparameterize_path(PlannerInfo *root, Path *path,
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index bec0c38617..095a5ea953 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -66,7 +66,8 @@ extern Agg *make_agg(List *tlist, List *qual,
int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators,
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 ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators);
/*
* prototypes for plan/initsplan.c
diff --git a/src/test/regress/expected/limit.out b/src/test/regress/expected/limit.out
index c18f547cbd..199725ec7f 100644
--- a/src/test/regress/expected/limit.out
+++ b/src/test/regress/expected/limit.out
@@ -503,3 +503,38 @@ 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 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..8009b746cb 100644
--- a/src/test/regress/sql/limit.sql
+++ b/src/test/regress/sql/limit.sql
@@ -141,3 +141,20 @@ 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 2 ROW ONLY;
+-- should fail
+SELECT ''::text AS two, unique1, unique2, stringu1
+ FROM onek WHERE unique1 > 50
+ FETCH FIRST 2 ROW WITH TIES;
