FETCH FIRST with PERCENT option is SQL standard that state limit count to
be specified in a percentage in addition to specify it in exact count and
listed as one of Major features simply not implemented yet in recent wiki
page [1].
I implemented it by executing the query plan twice. One without limit
filter to find the total number of row that will be feed to limit node so
the exact limit count can be calculated and the query plan execute again
with limit filter with newly calculated exact count .
[1].https://wiki.postgresql.org/wiki/PostgreSQL_vs_SQL_Standard
Regards
Surafel
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 4db8142afa..8491b7831a 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> ] [ PERCENT ] { ROW | ROWS } ONLY ]
[ 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> ] [ PERCENT ] { ROW | ROWS } ONLY
</synopsis>
In this syntax, the <replaceable class="parameter">start</replaceable>
or <replaceable class="parameter">count</replaceable> value is required by
@@ -1407,7 +1407,8 @@ 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>
+ with <literal>PERCENT</literal> count specifies the maximum number of rows to return
+ in percentage.<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.
diff --git a/src/backend/executor/nodeLimit.c b/src/backend/executor/nodeLimit.c
index bb28cf7d1d..8f1e937906 100644
--- a/src/backend/executor/nodeLimit.c
+++ b/src/backend/executor/nodeLimit.c
@@ -60,6 +60,24 @@ ExecLimit(PlanState *pstate)
{
case LIMIT_INITIAL:
+ if (node->limitOption == PERCENTAGE)
+ {
+
+ /*
+ * Find the total number of row the plan will return.
+ */
+ for (;;)
+ {
+ slot = ExecProcNode(outerPlan);
+ if (TupIsNull(slot))
+ {
+ break;
+ }
+ node->total++;
+ }
+ ExecReScan(outerPlan);
+ }
+
/*
* First call for this node, so compute limit/offset. (We can't do
* this any earlier, because parameters from upper nodes will not
@@ -283,11 +301,16 @@ recompute_limits(LimitState *node)
}
else
{
- node->count = DatumGetInt64(val);
- if (node->count < 0)
- ereport(ERROR,
- (errcode(ERRCODE_INVALID_ROW_COUNT_IN_LIMIT_CLAUSE),
- errmsg("LIMIT must not be negative")));
+ if (node->limitOption == PERCENTAGE)
+ node->count = (DatumGetInt64(val) * node->total) / 100;
+ else
+ {
+ node->count = DatumGetInt64(val);
+ if (node->count < 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_ROW_COUNT_IN_LIMIT_CLAUSE),
+ errmsg("LIMIT must not be negative")));
+ }
node->noCount = false;
}
}
@@ -374,6 +397,8 @@ ExecInitLimit(Limit *node, EState *estate, int eflags)
(PlanState *) limitstate);
limitstate->limitCount = ExecInitExpr((Expr *) node->limitCount,
(PlanState *) limitstate);
+ limitstate->limitOption = node->limitOption;
+ limitstate->total = 0;
/*
* Initialize result slot and type. (XXX not actually used, but upper
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 7c8220cf65..ba3e086e24 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1139,6 +1139,7 @@ _copyLimit(const Limit *from)
*/
COPY_NODE_FIELD(limitOffset);
COPY_NODE_FIELD(limitCount);
+ COPY_SCALAR_FIELD(limitOption);
return newnode;
}
@@ -3024,6 +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);
@@ -3108,6 +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 378f2facb8..ba74fe9ffc 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -973,6 +973,7 @@ _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);
@@ -1047,6 +1048,7 @@ _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 6269f474d2..a3572c73d4 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -986,6 +986,7 @@ _outLimit(StringInfo str, const Limit *node)
WRITE_NODE_FIELD(limitOffset);
WRITE_NODE_FIELD(limitCount);
+ WRITE_ENUM_FIELD(limitOption, LimitOption);
}
static void
@@ -2197,6 +2198,7 @@ _outLimitPath(StringInfo str, const LimitPath *node)
WRITE_NODE_FIELD(subpath);
WRITE_NODE_FIELD(limitOffset);
WRITE_NODE_FIELD(limitCount);
+ WRITE_ENUM_FIELD(limitOption, LimitOption);
}
static void
@@ -2785,6 +2787,7 @@ _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);
@@ -2995,6 +2998,7 @@ _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 3254524223..a10f989042 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -266,6 +266,7 @@ _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);
@@ -2286,6 +2287,7 @@ _readLimit(void)
READ_NODE_FIELD(limitOffset);
READ_NODE_FIELD(limitCount);
+ READ_ENUM_FIELD(limitOption, LimitOption);
READ_DONE();
}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index ae41c9efa0..e9df3ccda0 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -2139,7 +2139,8 @@ create_minmaxagg_plan(PlannerInfo *root, MinMaxAggPath *best_path)
plan = (Plan *) make_limit(plan,
subparse->limitOffset,
- subparse->limitCount);
+ subparse->limitCount,
+ subparse->limitOption);
/* Must apply correct cost/width data to Limit node */
plan->startup_cost = mminfo->path->startup_cost;
@@ -2444,7 +2445,8 @@ create_limit_plan(PlannerInfo *root, LimitPath *best_path, int flags)
plan = make_limit(subplan,
best_path->limitOffset,
- best_path->limitCount);
+ best_path->limitCount,
+ best_path->limitOption);
copy_generic_path_info(&plan->plan, (Path *) best_path);
@@ -6446,7 +6448,7 @@ 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)
{
Limit *node = makeNode(Limit);
Plan *plan = &node->plan;
@@ -6458,6 +6460,7 @@ make_limit(Plan *lefttree, Node *limitOffset, Node *limitCount)
node->limitOffset = limitOffset;
node->limitCount = limitCount;
+ node->limitOption = limitOption;
return node;
}
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 96bf0601a8..7322dfc90f 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2166,6 +2166,7 @@ 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 c5aaaf5c22..0315e434b6 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -3412,6 +3412,7 @@ 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);
@@ -3433,6 +3434,7 @@ 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 c601b6d40d..7c682c5c11 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -1301,6 +1301,7 @@ 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,
@@ -1547,6 +1548,7 @@ 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,
@@ -1782,6 +1784,7 @@ 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 87f5e95827..424fcfd418 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
@@ -662,7 +663,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
ORDER ORDINALITY OTHERS OUT_P OUTER_P
OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
- PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PLACING PLANS POLICY
+ PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PERCENT PLACING PLANS POLICY
POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
PRIOR PRIVILEGES PROCEDURAL PROCEDURE PROCEDURES PROGRAM PUBLICATION
@@ -11218,7 +11219,7 @@ select_no_parens:
| select_clause sort_clause
{
insertSelectOptions((SelectStmt *) $1, $2, NIL,
- NULL, NULL, NULL,
+ NULL, NULL, NULL, NULL,
yyscanner);
$$ = $1;
}
@@ -11226,6 +11227,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $1, $2, $3,
list_nth($4, 0), list_nth($4, 1),
+ (list_nth($4, 2)),
NULL,
yyscanner);
$$ = $1;
@@ -11234,6 +11236,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $1, $2, $4,
list_nth($3, 0), list_nth($3, 1),
+ list_nth($3, 2),
NULL,
yyscanner);
$$ = $1;
@@ -11242,7 +11245,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, NULL, NIL,
NULL, NULL,
- $1,
+ NULL, $1,
yyscanner);
$$ = $2;
}
@@ -11250,7 +11253,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, NIL,
NULL, NULL,
- $1,
+ NULL, $1,
yyscanner);
$$ = $2;
}
@@ -11258,6 +11261,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, $4,
list_nth($5, 0), list_nth($5, 1),
+ list_nth($5, 2),
$1,
yyscanner);
$$ = $2;
@@ -11266,6 +11270,7 @@ select_no_parens:
{
insertSelectOptions((SelectStmt *) $2, $3, $5,
list_nth($4, 0), list_nth($4, 1),
+ list_nth($4, 2),
$1,
yyscanner);
$$ = $2;
@@ -11552,20 +11557,20 @@ sortby: a_expr USING qual_all_Op opt_nulls_order
select_limit:
- limit_clause offset_clause { $$ = 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 */
@@ -11583,9 +11588,11 @@ 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("EXACT_NUMBER")); }
+ | FETCH first_or_next select_fetch_first_value PERCENT row_or_rows ONLY
+ { $$ = list_make2($3, makeString("PERCENTAGE")); }
| FETCH first_or_next row_or_rows ONLY
- { $$ = makeIntConst(1, -1); }
+ { $$ = list_make2(makeIntConst(1, -1), NULL); }
;
offset_clause:
@@ -15453,6 +15460,7 @@ reserved_keyword:
| ONLY
| OR
| ORDER
+ | PERCENT
| PLACING
| PRIMARY
| REFERENCES
@@ -15836,6 +15844,7 @@ static void
insertSelectOptions(SelectStmt *stmt,
List *sortClause, List *lockingClause,
Node *limitOffset, Node *limitCount,
+ void *limitOption,
WithClause *withClause,
core_yyscan_t yyscanner)
{
@@ -15874,6 +15883,17 @@ 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 (strcmp(strVal(limitOption), "PERCENTAGE") == 0)
+ stmt->limitOption = PERCENTAGE;
+ else
+ stmt->limitOption = EXACT_NUMBER;
+ }
if (withClause)
{
if (stmt->withClause)
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 41fa2052a2..4350da1907 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2219,8 +2219,10 @@ 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 */
+ int64 total; /* total number of row outer node return */
bool noCount; /* if true, ignore count */
LimitStateCond lstate; /* state machine status, as above */
int64 position; /* 1-based index of last tuple returned */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 697d3d7a5f..3a4ca4b27e 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -811,4 +811,16 @@ 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
+{
+ EXACT_NUMBER, /* LIMIT in exact number of rows */
+ PERCENTAGE /* LIMIT in percentage */
+} LimitOption;
+
#endif /* NODES_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 07ab1a3dde..58702f8afe 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 */
List *rowMarks; /* a list of RowMarkClause's */
@@ -1560,6 +1561,7 @@ 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 7c2abbd03a..e2cc85789b 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -952,6 +952,7 @@ typedef struct Limit
Plan plan;
Node *limitOffset; /* OFFSET parameter, or NULL if none */
Node *limitCount; /* COUNT parameter, or NULL if none */
+ LimitOption limitOption; /* LIMIT in percentage or exact number */
} Limit;
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 41caf873fb..cb69a68777 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1735,6 +1735,7 @@ 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; /* LIMIT in percentage or exact number */
} LimitPath;
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 7c5ff22650..17b62c7b8c 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 c8ab0280d2..4e1e3cebe2 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -64,7 +64,7 @@ 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);
/*
* prototypes for plan/initsplan.c
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 23db40147b..150d51df8f 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -300,6 +300,7 @@ PG_KEYWORD("partial", PARTIAL, UNRESERVED_KEYWORD)
PG_KEYWORD("partition", PARTITION, UNRESERVED_KEYWORD)
PG_KEYWORD("passing", PASSING, UNRESERVED_KEYWORD)
PG_KEYWORD("password", PASSWORD, UNRESERVED_KEYWORD)
+PG_KEYWORD("percent", PERCENT, RESERVED_KEYWORD)
PG_KEYWORD("placing", PLACING, RESERVED_KEYWORD)
PG_KEYWORD("plans", PLANS, UNRESERVED_KEYWORD)
PG_KEYWORD("policy", POLICY, UNRESERVED_KEYWORD)
diff --git a/src/test/regress/expected/create_table.out b/src/test/regress/expected/create_table.out
index 8927b21ba2..442b7622ea 100644
--- a/src/test/regress/expected/create_table.out
+++ b/src/test/regress/expected/create_table.out
@@ -79,7 +79,7 @@ CREATE TABLE student (
gpa float8
) INHERITS (person);
CREATE TABLE stud_emp (
- percent int4
+ "percent" int4
) INHERITS (emp, student);
NOTICE: merging multiple inherited definitions of column "name"
NOTICE: merging multiple inherited definitions of column "age"
diff --git a/src/test/regress/sql/create_table.sql b/src/test/regress/sql/create_table.sql
index 81fa7658b0..81ec6e368d 100644
--- a/src/test/regress/sql/create_table.sql
+++ b/src/test/regress/sql/create_table.sql
@@ -92,7 +92,7 @@ CREATE TABLE student (
CREATE TABLE stud_emp (
- percent int4
+ "percent" int4
) INHERITS (emp, student);
