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Allow to omit boundaries in array subscript
Allow to omiy lower or upper or both boundaries in array subscript for selecting slice of array. Author: YUriy Zhuravlev
1 parent 33bd250 commit 9246af6

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12 files changed

+184
-28
lines changed

12 files changed

+184
-28
lines changed

‎doc/src/sgml/array.sgml‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -255,6 +255,26 @@ SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = 'Bill';
255255
------------------------
256256
{{meeting},{training}}
257257
(1 row)
258+
</programlisting>
259+
260+
Possible to skip the <literal><replaceable>lower-bound</replaceable></literal> or
261+
<literal><replaceable>upper-bound</replaceable></literal>
262+
for get first or last element in slice.
263+
264+
<programlisting>
265+
SELECT schedule[:][:] FROM sal_emp WHERE name = 'Bill';
266+
267+
schedule
268+
------------------------
269+
{{meeting,lunch},{training,presentation}}
270+
(1 row)
271+
272+
SELECT schedule[:2][2:] FROM sal_emp WHERE name = 'Bill';
273+
274+
schedule
275+
------------------------
276+
{{lunch},{presentation}}
277+
(1 row)
258278
</programlisting>
259279

260280
If any dimension is written as a slice, i.e., contains a colon, then all

‎src/backend/executor/execQual.c‎

Lines changed: 35 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -268,10 +268,12 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
268268
bool eisnull;
269269
ListCell *l;
270270
int i = 0,
271-
j = 0;
271+
j = 0,
272+
indexexpr;
272273
IntArray upper,
273274
lower;
274275
int *lIndex;
276+
AnyArrayType *arrays;
275277

276278
array_source = ExecEvalExpr(astate->refexpr,
277279
econtext,
@@ -293,17 +295,31 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
293295
foreach(l, astate->refupperindexpr)
294296
{
295297
ExprState *eltstate = (ExprState *) lfirst(l);
298+
eisnull = false;
296299

297300
if (i >= MAXDIM)
298301
ereport(ERROR,
299302
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
300303
errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
301304
i + 1, MAXDIM)));
302305

303-
upper.indx[i++] = DatumGetInt32(ExecEvalExpr(eltstate,
304-
econtext,
305-
&eisnull,
306-
NULL));
306+
if (eltstate == NULL && astate->refattrlength <= 0)
307+
{
308+
if (isAssignment)
309+
ereport(ERROR,
310+
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
311+
errmsg("cannot determine upper index for empty array")));
312+
arrays = (AnyArrayType *)DatumGetArrayTypeP(array_source);
313+
indexexpr = AARR_LBOUND(arrays)[i] + AARR_DIMS(arrays)[i] - 1;
314+
}
315+
else
316+
indexexpr = DatumGetInt32(ExecEvalExpr(eltstate,
317+
econtext,
318+
&eisnull,
319+
NULL));
320+
321+
upper.indx[i++] = indexexpr;
322+
307323
/* If any index expr yields NULL, result is NULL or error */
308324
if (eisnull)
309325
{
@@ -321,17 +337,27 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
321337
foreach(l, astate->reflowerindexpr)
322338
{
323339
ExprState *eltstate = (ExprState *) lfirst(l);
340+
eisnull = false;
324341

325342
if (j >= MAXDIM)
326343
ereport(ERROR,
327344
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
328345
errmsg("number of array dimensions (%d) exceeds the maximum allowed (%d)",
329346
j + 1, MAXDIM)));
330347

331-
lower.indx[j++] = DatumGetInt32(ExecEvalExpr(eltstate,
332-
econtext,
333-
&eisnull,
334-
NULL));
348+
if (eltstate == NULL)
349+
{
350+
arrays = (AnyArrayType *)DatumGetArrayTypeP(array_source);
351+
indexexpr = AARR_LBOUND(arrays)[j];
352+
}
353+
else
354+
indexexpr = DatumGetInt32(ExecEvalExpr(eltstate,
355+
econtext,
356+
&eisnull,
357+
NULL));
358+
359+
lower.indx[j++] = indexexpr;
360+
335361
/* If any index expr yields NULL, result is NULL or error */
336362
if (eisnull)
337363
{

‎src/backend/nodes/copyfuncs.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2403,6 +2403,8 @@ _copyAIndices(const A_Indices *from)
24032403

24042404
COPY_NODE_FIELD(lidx);
24052405
COPY_NODE_FIELD(uidx);
2406+
COPY_SCALAR_FIELD(lidx_default);
2407+
COPY_SCALAR_FIELD(uidx_default);
24062408

24072409
return newnode;
24082410
}

‎src/backend/nodes/equalfuncs.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2153,6 +2153,8 @@ _equalAIndices(const A_Indices *a, const A_Indices *b)
21532153
{
21542154
COMPARE_NODE_FIELD(lidx);
21552155
COMPARE_NODE_FIELD(uidx);
2156+
COMPARE_SCALAR_FIELD(lidx_default);
2157+
COMPARE_SCALAR_FIELD(uidx_default);
21562158

21572159
return true;
21582160
}

‎src/backend/nodes/outfuncs.c‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2765,6 +2765,8 @@ _outA_Indices(StringInfo str, const A_Indices *node)
27652765

27662766
WRITE_NODE_FIELD(lidx);
27672767
WRITE_NODE_FIELD(uidx);
2768+
WRITE_BOOL_FIELD(lidx_default);
2769+
WRITE_BOOL_FIELD(uidx_default);
27682770
}
27692771

27702772
static void

‎src/backend/parser/gram.y‎

Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -13193,13 +13193,44 @@ indirection_el:
1319313193
A_Indices *ai = makeNode(A_Indices);
1319413194
ai->lidx = NULL;
1319513195
ai->uidx = $2;
13196+
ai->lidx_default = false;
13197+
ai->uidx_default = false;
13198+
$$ = (Node *) ai;
13199+
}
13200+
| '[' ':' ']'
13201+
{
13202+
A_Indices *ai = makeNode(A_Indices);
13203+
ai->lidx = NULL;
13204+
ai->uidx = NULL;
13205+
ai->lidx_default = true;
13206+
ai->uidx_default = true;
13207+
$$ = (Node *) ai;
13208+
}
13209+
| '[' ':' a_expr ']'
13210+
{
13211+
A_Indices *ai = makeNode(A_Indices);
13212+
ai->lidx = NULL;
13213+
ai->uidx = $3;
13214+
ai->lidx_default = true;
13215+
ai->uidx_default = false;
13216+
$$ = (Node *) ai;
13217+
}
13218+
| '[' a_expr ':' ']'
13219+
{
13220+
A_Indices *ai = makeNode(A_Indices);
13221+
ai->lidx = $2;
13222+
ai->uidx = NULL;
13223+
ai->lidx_default = false;
13224+
ai->uidx_default = true;
1319613225
$$ = (Node *) ai;
1319713226
}
1319813227
| '[' a_expr ':' a_expr ']'
1319913228
{
1320013229
A_Indices *ai = makeNode(A_Indices);
1320113230
ai->lidx = $2;
1320213231
ai->uidx = $4;
13232+
ai->lidx_default = false;
13233+
ai->uidx_default = false;
1320313234
$$ = (Node *) ai;
1320413235
}
1320513236
;

‎src/backend/parser/parse_node.c‎

Lines changed: 32 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -311,7 +311,7 @@ transformArraySubscripts(ParseState *pstate,
311311
elementType = transformArrayType(&arrayType, &arrayTypMod);
312312

313313
/*
314-
* A list containing only single subscripts refers to a single array
314+
* A list containing only single subscripts (uidx) refers to a single array
315315
* element. If any of the items are double subscripts (lower:upper), then
316316
* the subscript expression means an array slice operation. In this case,
317317
* we supply a default lower bound of 1 for any items that contain only a
@@ -322,7 +322,7 @@ transformArraySubscripts(ParseState *pstate,
322322
{
323323
A_Indices *ai = (A_Indices *) lfirst(idx);
324324

325-
if (ai->lidx != NULL)
325+
if (ai->lidx != NULL || ai->lidx_default)
326326
{
327327
isSlice = true;
328328
break;
@@ -335,9 +335,17 @@ transformArraySubscripts(ParseState *pstate,
335335
foreach(idx, indirection)
336336
{
337337
A_Indices *ai = (A_Indices *) lfirst(idx);
338-
Node *subexpr;
338+
Node *subexpr = NULL;
339339

340340
Assert(IsA(ai, A_Indices));
341+
if ((ai->uidx_default || ai->lidx_default) && assignFrom != NULL)
342+
ereport(ERROR,
343+
(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
344+
errmsg("array subscript must have both boundaries"),
345+
errhint("You can't omit the upper or lower"
346+
" boundaries when updating or inserting"),
347+
parser_errposition(pstate, exprLocation(arrayBase))));
348+
341349
if (isSlice)
342350
{
343351
if (ai->lidx)
@@ -356,7 +364,7 @@ transformArraySubscripts(ParseState *pstate,
356364
errmsg("array subscript must have type integer"),
357365
parser_errposition(pstate, exprLocation(ai->lidx))));
358366
}
359-
else
367+
else if (ai->lidx_default == false)
360368
{
361369
/* Make a constant 1 */
362370
subexpr = (Node *) makeConst(INT4OID,
@@ -369,19 +377,26 @@ transformArraySubscripts(ParseState *pstate,
369377
}
370378
lowerIndexpr = lappend(lowerIndexpr, subexpr);
371379
}
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))));
380+
381+
if (ai->uidx_default == false)
382+
{
383+
subexpr = transformExpr(pstate, ai->uidx, pstate->p_expr_kind);
384+
/* If it's not int4 already, try to coerce */
385+
subexpr = coerce_to_target_type(pstate,
386+
subexpr, exprType(subexpr),
387+
INT4OID, -1,
388+
COERCION_ASSIGNMENT,
389+
COERCE_IMPLICIT_CAST,
390+
-1);
391+
if (subexpr == NULL)
392+
ereport(ERROR,
393+
(errcode(ERRCODE_DATATYPE_MISMATCH),
394+
errmsg("array subscript must have type integer"),
395+
parser_errposition(pstate, exprLocation(ai->uidx))));
396+
}
397+
else
398+
subexpr = NULL;
399+
385400
upperIndexpr = lappend(upperIndexpr, subexpr);
386401
}
387402

‎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)->lidx != NULL || ((A_Indices *) n)->lidx_default)
654654
isSlice = true;
655655
}
656656
else if (IsA(n, A_Star))

‎src/include/nodes/parsenodes.h‎

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -358,6 +358,8 @@ typedef struct A_Indices
358358
NodeTag type;
359359
Node *lidx; /* NULL if it's a single subscript */
360360
Node *uidx;
361+
bool lidx_default;
362+
bool uidx_default;
361363
} A_Indices;
362364

363365
/*

‎src/test/regress/expected/arrays.out‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2031,3 +2031,43 @@ SELECT width_bucket(5, ARRAY[3, 4, NULL]);
20312031
ERROR: thresholds array must not contain NULLs
20322032
SELECT width_bucket(5, ARRAY[ARRAY[1, 2], ARRAY[3, 4]]);
20332033
ERROR: thresholds must be one-dimensional array
2034+
-- slices with empty lower and/or upper index
2035+
CREATE TABLE arrtest_s (
2036+
a int2[],
2037+
b int2[][]
2038+
);
2039+
INSERT INTO arrtest_s VALUES ('{1,2,3,4,5}', '{{1,2,3}, {4,5,6}, {7,8,9}}');
2040+
SELECT a[:3], b[:2][:2] FROM arrtest_s;
2041+
a | b
2042+
---------+---------------
2043+
{1,2,3} | {{1,2},{4,5}}
2044+
(1 row)
2045+
2046+
SELECT a[2:], b[2:][2:] FROM arrtest_s;
2047+
a | b
2048+
-----------+---------------
2049+
{2,3,4,5} | {{5,6},{8,9}}
2050+
(1 row)
2051+
2052+
SELECT a[:], b[:] FROM arrtest_s;
2053+
a | b
2054+
-------------+---------------------------
2055+
{1,2,3,4,5} | {{1,2,3},{4,5,6},{7,8,9}}
2056+
(1 row)
2057+
2058+
-- errors
2059+
UPDATE arrtest_s SET a[:3] = '{11, 12, 13}', b[:2][:2] = '{{11,12}, {14, 15}}';
2060+
ERROR: array subscript must have both boundaries
2061+
LINE 1: UPDATE arrtest_s SET a[:3] = '{11, 12, 13}', b[:2][:2] = '{{...
2062+
^
2063+
HINT: You can't omit the upper or lower boundaries when updating or inserting
2064+
UPDATE arrtest_s SET a[3:] = '{23, 24, 25}', b[2:][2:] = '{{25,26}, {28, 29}}';
2065+
ERROR: array subscript must have both boundaries
2066+
LINE 1: UPDATE arrtest_s SET a[3:] = '{23, 24, 25}', b[2:][2:] = '{{...
2067+
^
2068+
HINT: You can't omit the upper or lower boundaries when updating or inserting
2069+
UPDATE arrtest_s SET a[:] = '{23, 24, 25}';
2070+
ERROR: array subscript must have both boundaries
2071+
LINE 1: UPDATE arrtest_s SET a[:] = '{23, 24, 25}';
2072+
^
2073+
HINT: You can't omit the upper or lower boundaries when updating or inserting

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