[ 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>
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
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.
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
ExecLimit(PlanState *pstate)
{
LimitState *node = castNode(LimitState, pstate);
+ ExprContext *econtext = node->ps.ps_ExprContext;
ScanDirection direction;
TupleTableSlot *slot;
PlanState *outerPlan;
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;
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
if (!node->noCount &&
node->position - node->offset >= node->count)
{
- node->lstate = LIMIT_WINDOWEND;
+ if (node->limitOption == LIMIT_OPTION_COUNT)
+ {
+ node->lstate = LIMIT_WINDOWEND;
+ return NULL;
+ }
+ else
+ {
+ node->lstate = LIMIT_WINDOWEND_TIES;
+ /* fall-through */
+ }
+ }
+ else
+ {
+ /*
+ * 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;
+ }
+ }
+ else
+ {
+ /*
+ * Backwards scan, so check for stepping off start of window.
+ * As above, change only state-machine status if so.
+ */
+ if (node->position <= node->offset + 1)
+ {
+ node->lstate = LIMIT_WINDOWSTART;
return NULL;
}
/*
- * Get next tuple from subplan, if any.
+ * Get previous tuple from subplan; there should be one!
+ */
+ slot = ExecProcNode(outerPlan);
+ if (TupIsNull(slot))
+ 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;
}
- node->subSlot = slot;
- node->position++;
+
+ /*
+ * 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.
- * As above, change only state-machine status if so.
+ * Change only state-machine status if so.
*/
if (node->position <= node->offset + 1)
{
}
/*
- * Get previous tuple from subplan; there should be one!
+ * 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;
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:
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;
(PlanState *) limitstate);
limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
(PlanState *) limitstate);
+ limitstate->limitOption = node->limitOption;
/*
* Initialize result type.
*/
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;
}
*/
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;
}
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);
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);
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);
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);
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
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);
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);
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);
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();
}
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;
{
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);
* 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;
node->limitOffset = limitOffset;
node->limitCount = limitCount;
+ node->limitOption = limitOption;
+ node->uniqNumCols = uniqNumCols;
+ node->uniqColIdx = uniqColIdx;
+ node->uniqOperators = uniqOperators;
+ node->uniqCollations = uniqCollations;
return node;
}
path = (Path *) create_limit_path(root, final_rel, path,
parse->limitOffset,
parse->limitCount,
+ parse->limitOption,
offset_est, count_est);
}
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);
pathnode->subpath = subpath;
pathnode->limitOffset = limitOffset;
pathnode->limitCount = limitCount;
+ pathnode->limitOption = limitOption;
/*
* Adjust the output rows count and costs according to the offset/limit.
/* transform LIMIT */
qry->limitOffset = transformLimitClause(pstate, stmt->limitOffset,
- EXPR_KIND_OFFSET, "OFFSET");
+ EXPR_KIND_OFFSET, "OFFSET",
+ stmt->limitOption);
qry->limitCount = transformLimitClause(pstate, stmt->limitCount,
- EXPR_KIND_LIMIT, "LIMIT");
+ EXPR_KIND_LIMIT, "LIMIT",
+ stmt->limitOption);
+ qry->limitOption = stmt->limitOption;
/* transform window clauses after we have seen all window functions */
qry->windowClause = transformWindowDefinitions(pstate,
false /* allow SQL92 rules */ );
qry->limitOffset = transformLimitClause(pstate, stmt->limitOffset,
- EXPR_KIND_OFFSET, "OFFSET");
+ EXPR_KIND_OFFSET, "OFFSET",
+ stmt->limitOption);
qry->limitCount = transformLimitClause(pstate, stmt->limitCount,
- EXPR_KIND_LIMIT, "LIMIT");
+ EXPR_KIND_LIMIT, "LIMIT",
+ stmt->limitOption);
+ qry->limitOption = stmt->limitOption;
if (stmt->lockingClause)
ereport(ERROR,
exprLocation(list_nth(qry->targetList, tllen)))));
qry->limitOffset = transformLimitClause(pstate, limitOffset,
- EXPR_KIND_OFFSET, "OFFSET");
+ EXPR_KIND_OFFSET, "OFFSET",
+ stmt->limitOption);
qry->limitCount = transformLimitClause(pstate, limitCount,
- EXPR_KIND_LIMIT, "LIMIT");
+ EXPR_KIND_LIMIT, "LIMIT",
+ stmt->limitOption);
+ qry->limitOption = stmt->limitOption;
qry->rtable = pstate->p_rtable;
qry->jointree = makeFromExpr(pstate->p_joinlist, NULL);
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
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);
PartitionSpec *partspec;
PartitionBoundSpec *partboundspec;
RoleSpec *rolespec;
+ struct SelectLimit *selectlimit;
}
%type <node> stmt schema_stmt
%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
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
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
| 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;
| 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);
$$ = $1;
| with_clause select_clause
{
insertSelectOptions((SelectStmt *) $2, NULL, NIL,
- NULL, NULL,
+ NULL,
$1,
yyscanner);
$$ = $2;
| with_clause select_clause sort_clause
{
insertSelectOptions((SelectStmt *) $2, $3, NIL,
- NULL, NULL,
+ NULL,
$1,
yyscanner);
$$ = $2;
| with_clause select_clause opt_sort_clause for_locking_clause opt_select_limit
{
insertSelectOptions((SelectStmt *) $2, $3, $4,
- list_nth($5, 0), list_nth($5, 1),
+ $5,
$1,
yyscanner);
$$ = $2;
| 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);
$$ = $2;
select_limit:
- limit_clause offset_clause { $$ = 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 */
* 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:
static void
insertSelectOptions(SelectStmt *stmt,
List *sortClause, List *lockingClause,
- Node *limitOffset, Node *limitCount,
+ SelectLimit *limitClause,
WithClause *withClause,
core_yyscan_t yyscanner)
{
}
/* 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)
{
*/
Node *
transformLimitClause(ParseState *pstate, Node *clause,
- ParseExprKind exprKind, const char *constructName)
+ ParseExprKind exprKind, const char *constructName,
+ LimitOption limitOption)
{
Node *qual;
/* LIMIT can't refer to any variables of the current query */
checkExprIsVarFree(pstate, qual, constructName);
+ /*
+ * Don't allow NULLs in FETCH FIRST .. WITH TIES. This test is ugly and
+ * extremely simplistic, in that you can pass a NULL anyway by hiding it
+ * inside an expression -- but this protects ruleutils against emitting an
+ * unadorned NULL that's not accepted back by the grammar.
+ */
+ if (exprKind == EXPR_KIND_LIMIT && limitOption == LIMIT_OPTION_WITH_TIES &&
+ IsA(clause, A_Const) && ((A_Const *) clause)->val.type == T_Null)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_ROW_COUNT_IN_LIMIT_CLAUSE),
+ errmsg("row count cannot be NULL in FETCH FIRST ... WITH TIES clause")));
+
return qual;
}
force_colno, context);
}
- /* Add the LIMIT clause if given */
+ /*
+ * Add the LIMIT/OFFSET clauses if given. If non-default options, use the
+ * standard spelling of LIMIT.
+ */
if (query->limitOffset != NULL)
{
appendContextKeyword(context, " OFFSET ",
}
if (query->limitCount != NULL)
{
- appendContextKeyword(context, " LIMIT ",
- -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
- if (IsA(query->limitCount, Const) &&
- ((Const *) query->limitCount)->constisnull)
- appendStringInfoString(buf, "ALL");
- else
+ if (query->limitOption == LIMIT_OPTION_WITH_TIES)
+ {
+ appendContextKeyword(context, " FETCH FIRST ",
+ -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
get_rule_expr(query->limitCount, context, false);
+ appendStringInfo(buf, " ROWS WITH TIES");
+ }
+ else
+ {
+ appendContextKeyword(context, " LIMIT ",
+ -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
+ if (IsA(query->limitCount, Const) &&
+ ((Const *) query->limitCount)->constisnull)
+ appendStringInfoString(buf, "ALL");
+ else
+ get_rule_expr(query->limitCount, context, false);
+ }
}
/* Add FOR [KEY] UPDATE/SHARE clauses if present */
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 202004071
+#define CATALOG_VERSION_NO 202004072
#endif
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 */
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 */
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 */
Node *limitOffset; /* # of result tuples to skip (int8 expr) */
Node *limitCount; /* # of result tuples to return (int8 expr) */
+ LimitOption limitOption; /* limit type */
List *rowMarks; /* a list of RowMarkClause's */
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 */
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;
Plan plan;
Node *limitOffset; /* OFFSET parameter, or NULL if none */
Node *limitCount; /* COUNT parameter, or NULL if none */
+ LimitOption limitOption; /* limit type */
+ 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;
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,
int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations,
List *groupingSets, List *chain, double dNumGroups,
Size transitionSpace, 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
extern Node *transformWhereClause(ParseState *pstate, Node *clause,
ParseExprKind exprKind, const char *constructName);
extern Node *transformLimitClause(ParseState *pstate, Node *clause,
- ParseExprKind exprKind, const char *constructName);
+ ParseExprKind exprKind, const char *constructName,
+ LimitOption limitOption);
extern List *transformGroupClause(ParseState *pstate, List *grouplist,
List **groupingSets,
List **targetlist, List *sortClause,
----+----
(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
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
+-- test ruleutils
+CREATE VIEW limit_thousand_v_1 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST 5 ROWS WITH TIES OFFSET 10;
+\d+ limit_thousand_v_1
+ View "public.limit_thousand_v_1"
+ Column | Type | Collation | Nullable | Default | Storage | Description
+----------+---------+-----------+----------+---------+---------+-------------
+ thousand | integer | | | | plain |
+View definition:
+ SELECT onek.thousand
+ FROM onek
+ WHERE onek.thousand < 995
+ ORDER BY onek.thousand
+ OFFSET 10
+ FETCH FIRST 5 ROWS WITH TIES;
+
+CREATE VIEW limit_thousand_v_2 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand OFFSET 10 FETCH FIRST 5 ROWS ONLY;
+\d+ limit_thousand_v_2
+ View "public.limit_thousand_v_2"
+ Column | Type | Collation | Nullable | Default | Storage | Description
+----------+---------+-----------+----------+---------+---------+-------------
+ thousand | integer | | | | plain |
+View definition:
+ SELECT onek.thousand
+ FROM onek
+ WHERE onek.thousand < 995
+ ORDER BY onek.thousand
+ OFFSET 10
+ LIMIT 5;
+
+CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST NULL ROWS WITH TIES; -- fails
+ERROR: row count cannot be NULL in FETCH FIRST ... WITH TIES clause
+CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST (NULL+1) ROWS WITH TIES;
+\d+ limit_thousand_v_3
+ View "public.limit_thousand_v_3"
+ Column | Type | Collation | Nullable | Default | Storage | Description
+----------+---------+-----------+----------+---------+---------+-------------
+ thousand | integer | | | | plain |
+View definition:
+ SELECT onek.thousand
+ FROM onek
+ WHERE onek.thousand < 995
+ ORDER BY onek.thousand
+ FETCH FIRST (NULL::integer + 1) ROWS WITH TIES;
+
+CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST NULL ROWS ONLY;
+\d+ limit_thousand_v_4
+ View "public.limit_thousand_v_4"
+ Column | Type | Collation | Nullable | Default | Storage | Description
+----------+---------+-----------+----------+---------+---------+-------------
+ thousand | integer | | | | plain |
+View definition:
+ SELECT onek.thousand
+ FROM onek
+ WHERE onek.thousand < 995
+ ORDER BY onek.thousand
+ LIMIT ALL;
+
+-- leave these views
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
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;
+
+-- test ruleutils
+CREATE VIEW limit_thousand_v_1 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST 5 ROWS WITH TIES OFFSET 10;
+\d+ limit_thousand_v_1
+CREATE VIEW limit_thousand_v_2 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand OFFSET 10 FETCH FIRST 5 ROWS ONLY;
+\d+ limit_thousand_v_2
+CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST NULL ROWS WITH TIES; -- fails
+CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST (NULL+1) ROWS WITH TIES;
+\d+ limit_thousand_v_3
+CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995
+ ORDER BY thousand FETCH FIRST NULL ROWS ONLY;
+\d+ limit_thousand_v_4
+-- leave these views
projects / users / rhaas / postgres.git / commitdiff