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Commit11d5ba9

Browse files
committed
Fix ExecEvalArrayRef to pass down the old value of the array element or slice
being assigned to, in case the expression to be assigned is a FieldStore thatwould need to modify that value. The need for this was foreseen some timeago, but not implemented then because we did not have arrays of composites.Now we do, but the point evidently got overlooked in that patch. Net resultis that updating a field of an array element doesn't work right, asillustrated if you try the new regression test on an unpatched backend.Noted while experimenting with EXPLAIN VERBOSE, which has also got some issuesin this area.Backpatch to 8.3, where arrays of composites were introduced.
1 parent3e87ba6 commit11d5ba9

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3 files changed

+119
-12
lines changed

3 files changed

+119
-12
lines changed

‎src/backend/executor/execQual.c

Lines changed: 95 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.261 2010/01/11 15:31:04 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.262 2010/02/18 18:41:47 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -61,6 +61,7 @@
6161
staticDatumExecEvalArrayRef(ArrayRefExprState*astate,
6262
ExprContext*econtext,
6363
bool*isNull,ExprDoneCond*isDone);
64+
staticboolisAssignmentIndirectionExpr(ExprState*exprstate);
6465
staticDatumExecEvalAggref(AggrefExprState*aggref,
6566
ExprContext*econtext,
6667
bool*isNull,ExprDoneCond*isDone);
@@ -349,22 +350,74 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
349350
if (isAssignment)
350351
{
351352
DatumsourceData;
353+
Datumsave_datum;
354+
boolsave_isNull;
352355

353356
/*
354-
* Evaluate the value to be assigned into the array.
357+
* We might have a nested-assignment situation, in which the
358+
* refassgnexpr is itself a FieldStore or ArrayRef that needs to
359+
* obtain and modify the previous value of the array element or slice
360+
* being replaced. If so, we have to extract that value from the
361+
* array and pass it down via the econtext's caseValue. It's safe to
362+
* reuse the CASE mechanism because there cannot be a CASE between
363+
* here and where the value would be needed, and an array assignment
364+
* can't be within a CASE either. (So saving and restoring the
365+
* caseValue is just paranoia, but let's do it anyway.)
355366
*
356-
* XXX At some point we'll need to look into making the old value of
357-
* the array element available via CaseTestExpr, as is done by
358-
* ExecEvalFieldStore.This is not needed now but will be needed to
359-
* support arrays of composite types; in an assignment to a field of
360-
* an array member, the parser would generate a FieldStore that
361-
* expects to fetch its input tuple via CaseTestExpr.
367+
* Since fetching the old element might be a nontrivial expense, do it
368+
* only if the argument appears to actually need it.
369+
*/
370+
save_datum=econtext->caseValue_datum;
371+
save_isNull=econtext->caseValue_isNull;
372+
373+
if (isAssignmentIndirectionExpr(astate->refassgnexpr))
374+
{
375+
if (*isNull)
376+
{
377+
/* whole array is null, so any element or slice is too */
378+
econtext->caseValue_datum= (Datum)0;
379+
econtext->caseValue_isNull= true;
380+
}
381+
elseif (lIndex==NULL)
382+
{
383+
econtext->caseValue_datum=array_ref(array_source,i,
384+
upper.indx,
385+
astate->refattrlength,
386+
astate->refelemlength,
387+
astate->refelembyval,
388+
astate->refelemalign,
389+
&econtext->caseValue_isNull);
390+
}
391+
else
392+
{
393+
resultArray=array_get_slice(array_source,i,
394+
upper.indx,lower.indx,
395+
astate->refattrlength,
396+
astate->refelemlength,
397+
astate->refelembyval,
398+
astate->refelemalign);
399+
econtext->caseValue_datum=PointerGetDatum(resultArray);
400+
econtext->caseValue_isNull= false;
401+
}
402+
}
403+
else
404+
{
405+
/* argument shouldn't need caseValue, but for safety set it null */
406+
econtext->caseValue_datum= (Datum)0;
407+
econtext->caseValue_isNull= true;
408+
}
409+
410+
/*
411+
* Evaluate the value to be assigned into the array.
362412
*/
363413
sourceData=ExecEvalExpr(astate->refassgnexpr,
364414
econtext,
365415
&eisnull,
366416
NULL);
367417

418+
econtext->caseValue_datum=save_datum;
419+
econtext->caseValue_isNull=save_isNull;
420+
368421
/*
369422
* For an assignment to a fixed-length array type, both the original
370423
* array and the value to be assigned into it must be non-NULL, else
@@ -426,6 +479,34 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
426479
}
427480
}
428481

482+
/*
483+
* Helper for ExecEvalArrayRef: is expr a nested FieldStore or ArrayRef
484+
* that might need the old element value passed down?
485+
*
486+
* (We could use this in ExecEvalFieldStore too, but in that case passing
487+
* the old value is so cheap there's no need.)
488+
*/
489+
staticbool
490+
isAssignmentIndirectionExpr(ExprState*exprstate)
491+
{
492+
if (exprstate==NULL)
493+
return false;/* just paranoia */
494+
if (IsA(exprstate,FieldStoreState))
495+
{
496+
FieldStore*fstore= (FieldStore*)exprstate->expr;
497+
498+
if (fstore->arg&&IsA(fstore->arg,CaseTestExpr))
499+
return true;
500+
}
501+
elseif (IsA(exprstate,ArrayRefExprState))
502+
{
503+
ArrayRef*arrayRef= (ArrayRef*)exprstate->expr;
504+
505+
if (arrayRef->refexpr&&IsA(arrayRef->refexpr,CaseTestExpr))
506+
return true;
507+
}
508+
return false;
509+
}
429510

430511
/* ----------------------------------------------------------------
431512
*ExecEvalAggref
@@ -3902,10 +3983,12 @@ ExecEvalFieldStore(FieldStoreState *fstate,
39023983

39033984
/*
39043985
* Use the CaseTestExpr mechanism to pass down the old value of the
3905-
* field being replaced; this is useful in case we have a nested field
3906-
* update situation. It's safe to reuse the CASE mechanism because
3907-
* there cannot be a CASE between here and where the value would be
3908-
* needed.
3986+
* field being replaced; this is needed in case the newval is itself a
3987+
* FieldStore or ArrayRef that has to obtain and modify the old value.
3988+
* It's safe to reuse the CASE mechanism because there cannot be a
3989+
* CASE between here and where the value would be needed, and a field
3990+
* assignment can't be within a CASE either. (So saving and restoring
3991+
* the caseValue is just paranoia, but let's do it anyway.)
39093992
*/
39103993
econtext->caseValue_datum=values[fieldnum-1];
39113994
econtext->caseValue_isNull=isnull[fieldnum-1];

‎src/test/regress/expected/arrays.out

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1192,3 +1192,19 @@ select unnest(array[1,2,3,null,4,null,null,5,6]::text[]);
11921192
6
11931193
(9 rows)
11941194

1195+
-- Insert/update on a column that is array of composite
1196+
create temp table t1 (f1 int8_tbl[]);
1197+
insert into t1 (f1[5].q1) values(42);
1198+
select * from t1;
1199+
f1
1200+
-----------------
1201+
[5:5]={"(42,)"}
1202+
(1 row)
1203+
1204+
update t1 set f1[5].q2 = 43;
1205+
select * from t1;
1206+
f1
1207+
-------------------
1208+
[5:5]={"(42,43)"}
1209+
(1 row)
1210+

‎src/test/regress/sql/arrays.sql

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -404,3 +404,11 @@ select unnest(array[1,2,3,4.5]::float8[]);
404404
select unnest(array[1,2,3,4.5]::numeric[]);
405405
select unnest(array[1,2,3,null,4,null,null,5,6]);
406406
select unnest(array[1,2,3,null,4,null,null,5,6]::text[]);
407+
408+
-- Insert/update on a column that is array of composite
409+
410+
create temp table t1 (f1 int8_tbl[]);
411+
insert into t1 (f1[5].q1)values(42);
412+
select*from t1;
413+
update t1set f1[5].q2=43;
414+
select*from t1;

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