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Commit6efbded

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Allow omitting one or both boundaries in an array slice specifier.
Omitted boundaries represent the upper or lower limit of the correspondingarray subscript. This allows simpler specification of many commonuse-cases.(Revised version of commit9246af6)YUriy Zhuravlev
1 parent0ba3f3b commit6efbded

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15 files changed

+302
-33
lines changed

15 files changed

+302
-33
lines changed

‎doc/src/sgml/array.sgml‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -276,6 +276,29 @@ SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';
276276
for all dimensions, e.g., <literal>[1:2][1:1]</>, not <literal>[2][1:1]</>.
277277
</para>
278278

279+
<para>
280+
It is possible to omit the <replaceable>lower-bound</replaceable> and/or
281+
<replaceable>upper-bound</replaceable> of a slice specifier; the missing
282+
bound is replaced by the lower or upper limit of the array's subscripts.
283+
For example:
284+
285+
<programlisting>
286+
SELECT schedule[:2][2:] FROM sal_emp WHERE name = 'Bill';
287+
288+
schedule
289+
------------------------
290+
{{lunch},{presentation}}
291+
(1 row)
292+
293+
SELECT schedule[:][1:1] FROM sal_emp WHERE name = 'Bill';
294+
295+
schedule
296+
------------------------
297+
{{meeting},{training}}
298+
(1 row)
299+
</programlisting>
300+
</para>
301+
279302
<para>
280303
An array subscript expression will return null if either the array itself or
281304
any of the subscript expressions are null. Also, null is returned if a
@@ -391,6 +414,10 @@ UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}'
391414
WHERE name = 'Carol';
392415
</programlisting>
393416

417+
The slice syntaxes with omitted <replaceable>lower-bound</replaceable> and/or
418+
<replaceable>upper-bound</replaceable> can be used too, but only when
419+
updating an array value that is not NULL or zero-dimensional (otherwise,
420+
there is no existing subscript limit to substitute).
394421
</para>
395422

396423
<para>

‎src/backend/executor/execQual.c‎

Lines changed: 22 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -271,6 +271,8 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
271271
j=0;
272272
IntArrayupper,
273273
lower;
274+
boolupperProvided[MAXDIM],
275+
lowerProvided[MAXDIM];
274276
int*lIndex;
275277

276278
array_source=ExecEvalExpr(astate->refexpr,
@@ -300,6 +302,15 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
300302
errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
301303
i+1,MAXDIM)));
302304

305+
if (eltstate==NULL)
306+
{
307+
/* Slice bound is omitted, so use array's upper bound */
308+
Assert(astate->reflowerindexpr!=NIL);
309+
upperProvided[i++]= false;
310+
continue;
311+
}
312+
upperProvided[i]= true;
313+
303314
upper.indx[i++]=DatumGetInt32(ExecEvalExpr(eltstate,
304315
econtext,
305316
&eisnull,
@@ -328,6 +339,14 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
328339
errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
329340
j+1,MAXDIM)));
330341

342+
if (eltstate==NULL)
343+
{
344+
/* Slice bound is omitted, so use array's lower bound */
345+
lowerProvided[j++]= false;
346+
continue;
347+
}
348+
lowerProvided[j]= true;
349+
331350
lower.indx[j++]=DatumGetInt32(ExecEvalExpr(eltstate,
332351
econtext,
333352
&eisnull,
@@ -398,6 +417,7 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
398417
econtext->caseValue_datum=
399418
array_get_slice(array_source,i,
400419
upper.indx,lower.indx,
420+
upperProvided,lowerProvided,
401421
astate->refattrlength,
402422
astate->refelemlength,
403423
astate->refelembyval,
@@ -456,6 +476,7 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
456476
else
457477
returnarray_set_slice(array_source,i,
458478
upper.indx,lower.indx,
479+
upperProvided,lowerProvided,
459480
sourceData,
460481
eisnull,
461482
astate->refattrlength,
@@ -475,6 +496,7 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
475496
else
476497
returnarray_get_slice(array_source,i,
477498
upper.indx,lower.indx,
499+
upperProvided,lowerProvided,
478500
astate->refattrlength,
479501
astate->refelemlength,
480502
astate->refelembyval,

‎src/backend/nodes/copyfuncs.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2401,6 +2401,7 @@ _copyAIndices(const A_Indices *from)
24012401
{
24022402
A_Indices*newnode=makeNode(A_Indices);
24032403

2404+
COPY_SCALAR_FIELD(is_slice);
24042405
COPY_NODE_FIELD(lidx);
24052406
COPY_NODE_FIELD(uidx);
24062407

‎src/backend/nodes/equalfuncs.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2151,6 +2151,7 @@ _equalAStar(const A_Star *a, const A_Star *b)
21512151
staticbool
21522152
_equalAIndices(constA_Indices*a,constA_Indices*b)
21532153
{
2154+
COMPARE_SCALAR_FIELD(is_slice);
21542155
COMPARE_NODE_FIELD(lidx);
21552156
COMPARE_NODE_FIELD(uidx);
21562157

‎src/backend/nodes/outfuncs.c‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2763,6 +2763,7 @@ _outA_Indices(StringInfo str, const A_Indices *node)
27632763
{
27642764
WRITE_NODE_TYPE("A_INDICES");
27652765

2766+
WRITE_BOOL_FIELD(is_slice);
27662767
WRITE_NODE_FIELD(lidx);
27672768
WRITE_NODE_FIELD(uidx);
27682769
}

‎src/backend/parser/gram.y‎

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -434,7 +434,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
434434
%type<node>columnDefcolumnOptions
435435
%type<defelt>def_elemreloption_elemold_aggr_elemoperator_def_elem
436436
%type<node>def_argcolumnElemwhere_clausewhere_or_current_clause
437-
a_exprb_exprc_exprAexprConstindirection_el
437+
a_exprb_exprc_exprAexprConstindirection_elopt_slice_bound
438438
columnrefin_exprhaving_clausefunc_tablearray_expr
439439
ExclusionWhereClause
440440
%type<list>rowsfrom_itemrowsfrom_listopt_col_def_list
@@ -13191,19 +13191,26 @@ indirection_el:
1319113191
|'[' a_expr']'
1319213192
{
1319313193
A_Indices *ai =makeNode(A_Indices);
13194+
ai->is_slice =false;
1319413195
ai->lidx =NULL;
1319513196
ai->uidx = $2;
1319613197
$$ = (Node *) ai;
1319713198
}
13198-
|'['a_expr':'a_expr']'
13199+
|'['opt_slice_bound':'opt_slice_bound']'
1319913200
{
1320013201
A_Indices *ai =makeNode(A_Indices);
13202+
ai->is_slice =true;
1320113203
ai->lidx = $2;
1320213204
ai->uidx = $4;
1320313205
$$ = (Node *) ai;
1320413206
}
1320513207
;
1320613208

13209+
opt_slice_bound:
13210+
a_expr{ $$ = $1; }
13211+
|/*EMPTY*/{ $$ =NULL; }
13212+
;
13213+
1320713214
indirection:
1320813215
indirection_el{ $$ =list_make1($1); }
1320913216
| indirection indirection_el{ $$ =lappend($1, $2); }

‎src/backend/parser/parse_node.c‎

Lines changed: 38 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -311,18 +311,18 @@ transformArraySubscripts(ParseState *pstate,
311311
elementType=transformArrayType(&arrayType,&arrayTypMod);
312312

313313
/*
314-
* A list containing onlysingle subscripts refers to a single array
315-
* element. If any of the items aredouble subscripts (lower:upper), then
316-
* the subscript expression means an array slice operation. In this case,
317-
* wesupply a default lower bound of 1 for any items that contain only a
318-
*singlesubscript. We have to prescan the indirection list to see if
319-
* there are anydouble subscripts.
314+
* A list containing onlysimple subscripts refers to a single array
315+
* element. If any of the items areslice specifiers (lower:upper), then
316+
* the subscript expression means an array slice operation.In this case,
317+
* weconvert any non-slice items to slices by treating the single
318+
* subscript as the upper bound and supplying an assumed lower bound of 1.
319+
*We have to prescan the list to see ifthere are anyslice items.
320320
*/
321321
foreach(idx,indirection)
322322
{
323323
A_Indices*ai= (A_Indices*)lfirst(idx);
324324

325-
if (ai->lidx!=NULL)
325+
if (ai->is_slice)
326326
{
327327
isSlice= true;
328328
break;
@@ -356,7 +356,7 @@ transformArraySubscripts(ParseState *pstate,
356356
errmsg("array subscript must have type integer"),
357357
parser_errposition(pstate,exprLocation(ai->lidx))));
358358
}
359-
else
359+
elseif (!ai->is_slice)
360360
{
361361
/* Make a constant 1 */
362362
subexpr= (Node*)makeConst(INT4OID,
@@ -367,21 +367,38 @@ transformArraySubscripts(ParseState *pstate,
367367
false,
368368
true);/* pass by value */
369369
}
370+
else
371+
{
372+
/* Slice with omitted lower bound, put NULL into the list */
373+
subexpr=NULL;
374+
}
370375
lowerIndexpr=lappend(lowerIndexpr,subexpr);
371376
}
372-
subexpr=transformExpr(pstate,ai->uidx,pstate->p_expr_kind);
373-
/* If it's not int4 already, try to coerce */
374-
subexpr=coerce_to_target_type(pstate,
375-
subexpr,exprType(subexpr),
376-
INT4OID,-1,
377-
COERCION_ASSIGNMENT,
378-
COERCE_IMPLICIT_CAST,
379-
-1);
380-
if (subexpr==NULL)
381-
ereport(ERROR,
382-
(errcode(ERRCODE_DATATYPE_MISMATCH),
383-
errmsg("array subscript must have type integer"),
384-
parser_errposition(pstate,exprLocation(ai->uidx))));
377+
else
378+
Assert(ai->lidx==NULL&& !ai->is_slice);
379+
380+
if (ai->uidx)
381+
{
382+
subexpr=transformExpr(pstate,ai->uidx,pstate->p_expr_kind);
383+
/* If it's not int4 already, try to coerce */
384+
subexpr=coerce_to_target_type(pstate,
385+
subexpr,exprType(subexpr),
386+
INT4OID,-1,
387+
COERCION_ASSIGNMENT,
388+
COERCE_IMPLICIT_CAST,
389+
-1);
390+
if (subexpr==NULL)
391+
ereport(ERROR,
392+
(errcode(ERRCODE_DATATYPE_MISMATCH),
393+
errmsg("array subscript must have type integer"),
394+
parser_errposition(pstate,exprLocation(ai->uidx))));
395+
}
396+
else
397+
{
398+
/* Slice with omitted upper bound, put NULL into the list */
399+
Assert(isSlice&&ai->is_slice);
400+
subexpr=NULL;
401+
}
385402
upperIndexpr=lappend(upperIndexpr,subexpr);
386403
}
387404

‎src/backend/parser/parse_target.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -650,7 +650,7 @@ transformAssignmentIndirection(ParseState *pstate,
650650
if (IsA(n,A_Indices))
651651
{
652652
subscripts=lappend(subscripts,n);
653-
if (((A_Indices*)n)->lidx!=NULL)
653+
if (((A_Indices*)n)->is_slice)
654654
isSlice= true;
655655
}
656656
elseif (IsA(n,A_Star))

‎src/backend/utils/adt/arrayfuncs.c‎

Lines changed: 31 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1995,6 +1995,8 @@ array_get_element_expanded(Datum arraydatum,
19951995
*nSubscripts: number of subscripts supplied (must be same for upper/lower)
19961996
*upperIndx[]: the upper subscript values
19971997
*lowerIndx[]: the lower subscript values
1998+
*upperProvided[]: true for provided upper subscript values
1999+
*lowerProvided[]: true for provided lower subscript values
19982000
*arraytyplen: pg_type.typlen for the array type
19992001
*elmlen: pg_type.typlen for the array's element type
20002002
*elmbyval: pg_type.typbyval for the array's element type
@@ -2003,6 +2005,9 @@ array_get_element_expanded(Datum arraydatum,
20032005
* Outputs:
20042006
*The return value is the new array Datum (it's never NULL)
20052007
*
2008+
* Omitted upper and lower subscript values are replaced by the corresponding
2009+
* array bound.
2010+
*
20062011
* NOTE: we assume it is OK to scribble on the provided subscript arrays
20072012
* lowerIndx[] and upperIndx[]. These are generally just temporaries.
20082013
*/
@@ -2011,6 +2016,8 @@ array_get_slice(Datum arraydatum,
20112016
intnSubscripts,
20122017
int*upperIndx,
20132018
int*lowerIndx,
2019+
bool*upperProvided,
2020+
bool*lowerProvided,
20142021
intarraytyplen,
20152022
intelmlen,
20162023
boolelmbyval,
@@ -2081,9 +2088,9 @@ array_get_slice(Datum arraydatum,
20812088

20822089
for (i=0;i<nSubscripts;i++)
20832090
{
2084-
if (lowerIndx[i]<lb[i])
2091+
if (!lowerProvided[i]||lowerIndx[i]<lb[i])
20852092
lowerIndx[i]=lb[i];
2086-
if (upperIndx[i] >= (dim[i]+lb[i]))
2093+
if (!upperProvided[i]||upperIndx[i] >= (dim[i]+lb[i]))
20872094
upperIndx[i]=dim[i]+lb[i]-1;
20882095
if (lowerIndx[i]>upperIndx[i])
20892096
returnPointerGetDatum(construct_empty_array(elemtype));
@@ -2708,6 +2715,8 @@ array_set_element_expanded(Datum arraydatum,
27082715
*nSubscripts: number of subscripts supplied (must be same for upper/lower)
27092716
*upperIndx[]: the upper subscript values
27102717
*lowerIndx[]: the lower subscript values
2718+
*upperProvided[]: true for provided upper subscript values
2719+
*lowerProvided[]: true for provided lower subscript values
27112720
*srcArrayDatum: the source for the inserted values
27122721
*isNull: indicates whether srcArrayDatum is NULL
27132722
*arraytyplen: pg_type.typlen for the array type
@@ -2719,6 +2728,9 @@ array_set_element_expanded(Datum arraydatum,
27192728
* A new array is returned, just like the old except for the
27202729
* modified range. The original array object is not changed.
27212730
*
2731+
* Omitted upper and lower subscript values are replaced by the corresponding
2732+
* array bound.
2733+
*
27222734
* For one-dimensional arrays only, we allow the array to be extended
27232735
* by assigning to positions outside the existing subscript range; any
27242736
* positions between the existing elements and the new ones are set to NULLs.
@@ -2735,6 +2747,8 @@ array_set_slice(Datum arraydatum,
27352747
intnSubscripts,
27362748
int*upperIndx,
27372749
int*lowerIndx,
2750+
bool*upperProvided,
2751+
bool*lowerProvided,
27382752
DatumsrcArrayDatum,
27392753
boolisNull,
27402754
intarraytyplen,
@@ -2806,6 +2820,13 @@ array_set_slice(Datum arraydatum,
28062820

28072821
for (i=0;i<nSubscripts;i++)
28082822
{
2823+
if (!upperProvided[i]|| !lowerProvided[i])
2824+
ereport(ERROR,
2825+
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
2826+
errmsg("array slice subscript must provide both boundaries"),
2827+
errdetail("When assigning to a slice of an empty array value,"
2828+
" slice boundaries must be fully specified.")));
2829+
28092830
dim[i]=1+upperIndx[i]-lowerIndx[i];
28102831
lb[i]=lowerIndx[i];
28112832
}
@@ -2839,6 +2860,10 @@ array_set_slice(Datum arraydatum,
28392860
if (ndim==1)
28402861
{
28412862
Assert(nSubscripts==1);
2863+
if (!lowerProvided[0])
2864+
lowerIndx[0]=lb[0];
2865+
if (!upperProvided[0])
2866+
upperIndx[0]=dim[0]+lb[0]-1;
28422867
if (lowerIndx[0]>upperIndx[0])
28432868
ereport(ERROR,
28442869
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
@@ -2867,6 +2892,10 @@ array_set_slice(Datum arraydatum,
28672892
*/
28682893
for (i=0;i<nSubscripts;i++)
28692894
{
2895+
if (!lowerProvided[i])
2896+
lowerIndx[i]=lb[i];
2897+
if (!upperProvided[i])
2898+
upperIndx[i]=dim[i]+lb[i]-1;
28702899
if (lowerIndx[i]>upperIndx[i])
28712900
ereport(ERROR,
28722901
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),

‎src/backend/utils/adt/ruleutils.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -9372,10 +9372,12 @@ printSubscripts(ArrayRef *aref, deparse_context *context)
93729372
appendStringInfoChar(buf,'[');
93739373
if (lowlist_item)
93749374
{
9375+
/* If subexpression is NULL, get_rule_expr prints nothing */
93759376
get_rule_expr((Node*)lfirst(lowlist_item),context, false);
93769377
appendStringInfoChar(buf,':');
93779378
lowlist_item=lnext(lowlist_item);
93789379
}
9380+
/* If subexpression is NULL, get_rule_expr prints nothing */
93799381
get_rule_expr((Node*)lfirst(uplist_item),context, false);
93809382
appendStringInfoChar(buf,']');
93819383
}

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