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Commit2f4c9d3

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Okay, here's my attempt at fixing the problems with parentheses in
subqueries. It passes the normal 'runcheck' tests, and I've trieda few simple things like select 1 as foo union (((((select 2))))) order by foo;There are a few things that it doesn't do that have been talkedabout here at least a little:1) It doesn't allow things like "IN(((select 1)))" -- the selecthere has to be at the top level. This is not new.2) It does NOT preserve the odd syntax I found when I started lookingat this, where a SELECT statement could begin with parentheses. Thus, (SELECT a from foo) order by a;fails.I have preserved the ability, used in the regression tests, tohave a single select statement in what appears to be a RuleActionMulti(but wasn't -- the parens were part of select_clause syntax).In my version, this is a special form.This may cause some discussion: I have differentiated the two kindsof RuleActionMulti. Perhaps nobody knew there were two kinds, becauseI don't think the second form appears in the regression tests. Thisone uses square brackets instead of parentheses, but originally wasotherwise the same as the one in parentheses. In this version ofgram.y, the square bracket form treats SELECT statements the sameas the other allowed statements. As discussed before on this list,psql cannot make sense out of the results of such a thing, but anapplication might. And I have designs on just such an application.++ kevin o'gorman
1 parent3eb9b73 commit2f4c9d3

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1 file changed

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lines changed

1 file changed

+119
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lines changed

‎src/backend/parser/gram.y‎

Lines changed: 119 additions & 50 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
*
1212
*
1313
* IDENTIFICATION
14-
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.198 2000/10/25 18:56:16 tgl Exp $
14+
* $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.199 2000/10/28 15:44:04 momjian Exp $
1515
*
1616
* HISTORY
1717
* AUTHORDATEMAJOR EVENT
@@ -127,14 +127,15 @@ static void doNegateFloat(Value *v);
127127
DropGroupStmt,DropPLangStmt,DropSchemaStmt,DropStmt,DropTrigStmt,
128128
DropUserStmt,DropdbStmt,ExplainStmt,ExtendStmt,FetchStmt,
129129
GrantStmt,IndexStmt,InsertStmt,ListenStmt,LoadStmt,LockStmt,
130-
NotifyStmt,OptimizableStmt,ProcedureStmt,ReindexStmt,
130+
NotifyStmt,OptimizableStmt,ProcedureStmt
131+
QualifiedSelectStmt,ReindexStmt,
131132
RemoveAggrStmt,RemoveFuncStmt,RemoveOperStmt,
132133
RenameStmt,RevokeStmt,RuleActionStmt,RuleActionStmtOrEmpty,
133134
RuleStmt,SelectStmt,SetSessionStmt,TransactionStmt,TruncateStmt,
134135
UnlistenStmt,UpdateStmt,VacuumStmt,VariableResetStmt,
135136
VariableSetStmt,VariableShowStmt,ViewStmt
136137

137-
%type<node>select_clause,select_subclause
138+
%type<node>subquery,simple_select,select_head,set_select
138139

139140
%type<list>SessionList
140141
%type<node>SessionClause
@@ -177,19 +178,20 @@ static void doNegateFloat(Value *v);
177178
result,OptTempTableName,relation_name_list,OptTableElementList,
178179
OptUnder,OptInherit,definition,opt_distinct,
179180
opt_with,func_args,func_args_list,func_as,
180-
oper_argtypes,RuleActionList,RuleActionMulti,
181+
oper_argtypes,RuleActionList,RuleActionMulti,
182+
RuleActionOrSelectMulti,RuleActions,RuleActionBracket,
181183
opt_column_list,columnList,opt_va_list,va_list,
182184
sort_clause,sortby_list,index_params,index_list,name_list,
183185
from_clause,from_list,opt_array_bounds,
184186
expr_list,attrs,target_list,update_target_list,
185187
def_list,opt_indirection,group_clause,TriggerFuncArgs,
186-
opt_select_limit
188+
opt_select_limit,select_limit
187189

188190
%type<typnam>func_arg,func_return,aggr_argtype
189191

190192
%type<boolean>opt_arg,TriggerForOpt,TriggerForType,OptTemp
191193

192-
%type<list>for_update_clause,update_list
194+
%type<list>opt_for_update_clause,for_update_clause,update_list
193195
%type<boolean>opt_all
194196
%type<boolean>opt_table
195197
%type<boolean>opt_chain,opt_trans
@@ -2660,7 +2662,7 @@ opt_column: COLUMN{ $$ = COLUMN; }
26602662
RuleStmt:CREATERULEnameAS
26612663
{ QueryIsRule=TRUE; }
26622664
ONeventTOevent_objectwhere_clause
2663-
DOopt_insteadRuleActionList
2665+
DOopt_insteadRuleActions
26642666
{
26652667
RuleStmt *n = makeNode(RuleStmt);
26662668
n->rulename =$3;
@@ -2673,28 +2675,78 @@ RuleStmt: CREATE RULE name AS
26732675
}
26742676
;
26752677

2676-
RuleActionList:NOTHING{$$ = NIL; }
2677-
|SelectStmt{$$ = makeList1($1); }
2678-
|RuleActionStmt{$$ = makeList1($1); }
2679-
|'['RuleActionMulti']'{$$ =$2; }
2680-
|'('RuleActionMulti')'{$$ =$2; }
2678+
RuleActions:NOTHING{$$ = NIL; }
2679+
|RuleActionStmt{$$ = makeList1($1); }
2680+
|SelectStmt{$$ = makeList1($1); }
2681+
|RuleActionList
2682+
|RuleActionBracket
2683+
;
2684+
2685+
/* LEGACY: Version 7.0 did not like SELECT statements in these lists,
2686+
* but because of an oddity in the syntax for select_clause, allowed
2687+
* certain forms like "DO INSTEAD (select 1)", and this is used in
2688+
* the regression tests.
2689+
* Here, we're allowing just one SELECT in parentheses, to preserve
2690+
* any such expectations, and make the regression tests work.
2691+
* ++ KO'G
2692+
*/
2693+
RuleActionList:'('RuleActionMulti')'{$$ =$2; }
2694+
|'('SelectStmt')'{$$ = makeList1($2); }
2695+
;
2696+
2697+
/* An undocumented feature, bracketed lists are allowed to contain
2698+
* SELECT statements on the same basis as the others. Before this,
2699+
* they were the same as parenthesized lists, and did not allow
2700+
* SelectStmts. Anybody know why they were here originally? Or if
2701+
* they're in the regression tests at all?
2702+
* ++ KO'G
2703+
*/
2704+
RuleActionBracket:'['RuleActionOrSelectMulti']'{$$ =$2; }
26812705
;
26822706

26832707
/* the thrashing around here is to discard "empty" statements...*/
26842708
RuleActionMulti:RuleActionMulti';'RuleActionStmtOrEmpty
26852709
{if ($3 != (Node *)NULL)
2686-
$$ = lappend($1,$3);
2710+
if ($1 != NIL)
2711+
$$ = lappend($1,$3);
2712+
else
2713+
$$ = makeList1($3);
2714+
else
2715+
$$ =$1;
2716+
}
2717+
|RuleActionStmtOrEmpty
2718+
{if ($1 != (Node *)NULL)
2719+
$$ = makeList1($1);
2720+
else
2721+
$$ = NIL;
2722+
}
2723+
;
2724+
2725+
RuleActionOrSelectMulti:RuleActionOrSelectMulti';'RuleActionStmtOrEmpty
2726+
{if ($3 != (Node *)NULL)
2727+
if ($1 != NIL)
2728+
$$ = lappend($1,$3);
2729+
else
2730+
$$ = makeList1($3);
26872731
else
26882732
$$ =$1;
26892733
}
2734+
|RuleActionOrSelectMulti';'SelectStmt
2735+
{if ($1 != NIL)
2736+
$$ = lappend($1,$3);
2737+
else
2738+
$$ = makeList1($3);
2739+
}
26902740
|RuleActionStmtOrEmpty
26912741
{if ($1 != (Node *)NULL)
26922742
$$ = makeList1($1);
26932743
else
26942744
$$ = NIL;
26952745
}
2746+
|SelectStmt{$$ = makeList1($1); }
26962747
;
26972748

2749+
26982750
RuleActionStmt:InsertStmt
26992751
|UpdateStmt
27002752
|DeleteStmt
@@ -3248,7 +3300,12 @@ opt_cursor: BINARY{ $$ = TRUE; }
32483300
* However, this is not checked by the grammar; parse analysis must check it.
32493301
*/
32503302

3251-
SelectStmt:select_clausesort_clausefor_update_clauseopt_select_limit
3303+
SelectStmt:QualifiedSelectStmt
3304+
|select_head
3305+
;
3306+
3307+
QualifiedSelectStmt:
3308+
select_headsort_clauseopt_for_update_clauseopt_select_limit
32523309
{
32533310
SelectStmt *n = findLeftmostSelect($1);
32543311

@@ -3258,34 +3315,35 @@ SelectStmt: select_clause sort_clause for_update_clause opt_select_limit
32583315
n->limitCount = nth(1,$4);
32593316
$$ =$1;
32603317
}
3261-
;
3262-
3263-
/* This rule parses Select statements that can appear within set operations,
3264-
* including UNION, INTERSECT and EXCEPT. '(' and ')' can be used to specify
3265-
* the ordering of the set operations. Without '(' and ')' we want the
3266-
* operations to be ordered per the precedence specs at the head of this file.
3267-
*
3268-
* Since parentheses around SELECTs also appear in the expression grammar,
3269-
* there is a parse ambiguity if parentheses are allowed at the top level of a
3270-
* select_clause: are the parens part of the expression or part of the select?
3271-
* We separate select_clause into two levels to resolve this: select_clause
3272-
* can have top-level parentheses, select_subclause cannot.
3273-
*
3274-
* Note that sort clauses cannot be included at this level --- a sort clause
3275-
* can only appear at the end of the complete Select, and it will be handled
3276-
* by the topmost SelectStmt rule. Likewise FOR UPDATE and LIMIT.
3277-
*/
3278-
select_clause:'('select_subclause')'
3318+
|select_headfor_update_clauseopt_select_limit
32793319
{
3280-
$$ =$2;
3320+
SelectStmt *n = findLeftmostSelect($1);
3321+
3322+
n->sortClause =NULL;
3323+
n->forUpdate =$2;
3324+
n->limitOffset = nth(0,$3);
3325+
n->limitCount = nth(1,$3);
3326+
$$ =$1;
32813327
}
3282-
|select_subclause
3328+
|select_headselect_limit
32833329
{
3284-
$$ =$1;
3330+
SelectStmt *n = findLeftmostSelect($1);
3331+
3332+
n->sortClause =NULL;
3333+
n->forUpdate =NULL;
3334+
n->limitOffset = nth(0,$2);
3335+
n->limitCount = nth(1,$2);
3336+
$$ =$1;
32853337
}
32863338
;
32873339

3288-
select_subclause:SELECTopt_distincttarget_list
3340+
subquery:'('subquery')'{$$ =$2; }
3341+
|'('QualifiedSelectStmt')'{$$ =$2; }
3342+
|'('set_select')'{$$ =$2; }
3343+
|simple_select{$$ =$1; }
3344+
;
3345+
3346+
simple_select:SELECTopt_distincttarget_list
32893347
resultfrom_clausewhere_clause
32903348
group_clausehaving_clause
32913349
{
@@ -3300,7 +3358,13 @@ select_subclause: SELECT opt_distinct target_list
33003358
n->havingClause =$8;
33013359
$$ = (Node *)n;
33023360
}
3303-
|select_clauseUNIONopt_allselect_clause
3361+
;
3362+
3363+
select_head:simple_select{$$ =$1; }
3364+
|set_select{$$ =$1; }
3365+
;
3366+
3367+
set_select:select_headUNIONopt_allsubquery
33043368
{
33053369
SetOperationStmt *n = makeNode(SetOperationStmt);
33063370
n->op = SETOP_UNION;
@@ -3309,7 +3373,7 @@ select_subclause: SELECT opt_distinct target_list
33093373
n->rarg =$4;
33103374
$$ = (Node *) n;
33113375
}
3312-
|select_clauseINTERSECTopt_allselect_clause
3376+
|select_headINTERSECTopt_allsubquery
33133377
{
33143378
SetOperationStmt *n = makeNode(SetOperationStmt);
33153379
n->op = SETOP_INTERSECT;
@@ -3318,7 +3382,7 @@ select_subclause: SELECT opt_distinct target_list
33183382
n->rarg =$4;
33193383
$$ = (Node *) n;
33203384
}
3321-
|select_clauseEXCEPTopt_allselect_clause
3385+
|select_headEXCEPTopt_allsubquery
33223386
{
33233387
SetOperationStmt *n = makeNode(SetOperationStmt);
33243388
n->op = SETOP_EXCEPT;
@@ -3383,7 +3447,6 @@ opt_distinct: DISTINCT{ $$ = makeList1(NIL); }
33833447
;
33843448

33853449
sort_clause:ORDERBYsortby_list{$$ =$3; }
3386-
|/*EMPTY*/{$$ = NIL; }
33873450
;
33883451

33893452
sortby_list:sortby{$$ = makeList1($1); }
@@ -3405,7 +3468,7 @@ OptUseOp: USING all_Op{ $$ = $2; }
34053468
;
34063469

34073470

3408-
opt_select_limit:LIMITselect_limit_value','select_offset_value
3471+
select_limit:LIMITselect_limit_value','select_offset_value
34093472
{$$ = makeList2($4,$2); }
34103473
|LIMITselect_limit_valueOFFSETselect_offset_value
34113474
{$$ = makeList2($4,$2); }
@@ -3415,6 +3478,9 @@ opt_select_limit:LIMIT select_limit_value ',' select_offset_value
34153478
{$$ = makeList2($2,$4); }
34163479
|OFFSETselect_offset_value
34173480
{$$ = makeList2($2,NULL); }
3481+
;
3482+
3483+
opt_select_limit:select_limit{$$ =$1; }
34183484
|/* EMPTY*/
34193485
{$$ = makeList2(NULL,NULL); }
34203486
;
@@ -3514,6 +3580,9 @@ having_clause: HAVING a_expr
35143580

35153581
for_update_clause:FORUPDATEupdate_list{$$ =$3; }
35163582
|FORREADONLY{$$ =NULL; }
3583+
;
3584+
3585+
opt_for_update_clause:for_update_clause{$$ =$1; }
35173586
|/* EMPTY*/{$$ =NULL; }
35183587
;
35193588

@@ -3557,7 +3626,7 @@ table_ref: relation_expr
35573626
$1->name =$2;
35583627
$$ = (Node *)$1;
35593628
}
3560-
|'('select_subclause')'alias_clause
3629+
|'('SelectStmt')'alias_clause
35613630
{
35623631
RangeSubselect *n = makeNode(RangeSubselect);
35633632
n->subquery =$2;
@@ -4093,7 +4162,7 @@ opt_interval: datetime{ $$ = makeList1($1); }
40934162
* Define row_descriptor to allow yacc to break the reduce/reduce conflict
40944163
* with singleton expressions.
40954164
*/
4096-
row_expr:'('row_descriptor')'IN'('select_subclause')'
4165+
row_expr:'('row_descriptor')'IN'('SelectStmt')'
40974166
{
40984167
SubLink *n = makeNode(SubLink);
40994168
n->lefthand =$2;
@@ -4103,7 +4172,7 @@ row_expr: '(' row_descriptor ')' IN '(' select_subclause ')'
41034172
n->subselect =$6;
41044173
$$ = (Node *)n;
41054174
}
4106-
|'('row_descriptor')'NOTIN'('select_subclause')'
4175+
|'('row_descriptor')'NOTIN'('SelectStmt')'
41074176
{
41084177
SubLink *n = makeNode(SubLink);
41094178
n->lefthand =$2;
@@ -4113,7 +4182,7 @@ row_expr: '(' row_descriptor ')' IN '(' select_subclause ')'
41134182
n->subselect =$7;
41144183
$$ = (Node *)n;
41154184
}
4116-
|'('row_descriptor')'all_Opsub_type'('select_subclause')'
4185+
|'('row_descriptor')'all_Opsub_type'('SelectStmt')'
41174186
{
41184187
SubLink *n = makeNode(SubLink);
41194188
n->lefthand =$2;
@@ -4126,7 +4195,7 @@ row_expr: '(' row_descriptor ')' IN '(' select_subclause ')'
41264195
n->subselect =$7;
41274196
$$ = (Node *)n;
41284197
}
4129-
|'('row_descriptor')'all_Op'('select_subclause')'
4198+
|'('row_descriptor')'all_Op'('SelectStmt')'
41304199
{
41314200
SubLink *n = makeNode(SubLink);
41324201
n->lefthand =$2;
@@ -4457,7 +4526,7 @@ a_expr: c_expr
44574526
$$ = n;
44584527
}
44594528
}
4460-
|a_exprall_Opsub_type'('select_subclause')'
4529+
|a_exprall_Opsub_type'('SelectStmt')'
44614530
{
44624531
SubLink *n = makeNode(SubLink);
44634532
n->lefthand = makeList1($1);
@@ -4853,7 +4922,7 @@ c_expr: attr
48534922
n->agg_distinct =FALSE;
48544923
$$ = (Node *)n;
48554924
}
4856-
|'('select_subclause')'
4925+
|'('SelectStmt')'
48574926
{
48584927
SubLink *n = makeNode(SubLink);
48594928
n->lefthand = NIL;
@@ -4863,7 +4932,7 @@ c_expr: attr
48634932
n->subselect =$2;
48644933
$$ = (Node *)n;
48654934
}
4866-
|EXISTS'('select_subclause')'
4935+
|EXISTS'('SelectStmt')'
48674936
{
48684937
SubLink *n = makeNode(SubLink);
48694938
n->lefthand = NIL;
@@ -4962,7 +5031,7 @@ trim_list: a_expr FROM expr_list
49625031
{$$ =$1; }
49635032
;
49645033

4965-
in_expr:select_subclause
5034+
in_expr:SelectStmt
49665035
{
49675036
SubLink *n = makeNode(SubLink);
49685037
n->subselect =$1;

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