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Support assignment to subfields of composite columns in UPDATE and INSERT.

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As a side effect, cause subscripts in INSERT targetlists to do something
more or less sensible; previously we evaluated such subscripts and then
effectively ignored them.  Another side effect is that UPDATE-ing an
element or slice of an array value that is NULL now produces a non-null
result, namely an array containing just the assigned-to positions.
This commit is contained in:
Tom Lane
2004-06-09 19:08:20 +00:00
parent 3a0df651da
commit 7e64dbc6b5
27 changed files with 1468 additions and 574 deletions
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240
src/backend/executor/execQual.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.163 2004/06/05 19:48:08 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.164 2004/06/09 19:08:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -118,6 +118,9 @@ static Datum ExecEvalCoerceToDomainValue(ExprState *exprstate,
static Datum ExecEvalFieldSelect(FieldSelectState *fstate,
ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalFieldStore(FieldStoreState *fstate,
ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalRelabelType(GenericExprState *exprstate,
ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
@ -217,6 +220,7 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
ArrayType *array_source;
ArrayType *resultArray;
bool isAssignment = (arrayRef->refassgnexpr != NULL);
bool eisnull;
ListCell *l;
int i = 0,
j = 0;
@ -224,39 +228,23 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
lower;
int *lIndex;
/* Set default values for result flags: non-null, not a set result */
*isNull = false;
if (isDone)
*isDone = ExprSingleResult;
array_source = (ArrayType *)
DatumGetPointer(ExecEvalExpr(astate->refexpr,
econtext,
isNull,
isDone));
if (arrayRef->refexpr != NULL)
/*
* If refexpr yields NULL, and it's a fetch, then result is NULL.
* In the assignment case, we'll cons up something below.
*/
if (*isNull)
{
array_source = (ArrayType *)
DatumGetPointer(ExecEvalExpr(astate->refexpr,
econtext,
isNull,
isDone));
/*
* If refexpr yields NULL, result is always NULL, for now anyway.
* (This means you cannot assign to an element or slice of an
* array that's NULL; it'll just stay NULL.)
*/
if (*isNull)
if (isDone && *isDone == ExprEndResult)
return (Datum) NULL; /* end of set result */
if (!isAssignment)
return (Datum) NULL;
}
else
{
/*
* Empty refexpr indicates we are doing an INSERT into an array
* column. For now, we just take the refassgnexpr (which the
* parser will have ensured is an array value) and return it
* as-is, ignoring any subscripts that may have been supplied in
* the INSERT column list. This is a kluge, but it's not real
* clear what the semantics ought to be...
*/
array_source = NULL;
}
foreach(l, astate->refupperindexpr)
{
@ -270,14 +258,16 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
upper.indx[i++] = DatumGetInt32(ExecEvalExpr(eltstate,
econtext,
isNull,
&eisnull,
NULL));
/* If any index expr yields NULL, result is NULL or source array */
if (*isNull)
if (eisnull)
{
if (!isAssignment || array_source == NULL)
if (!isAssignment)
{
*isNull = true;
return (Datum) NULL;
*isNull = false;
}
return PointerGetDatum(array_source);
}
}
@ -296,18 +286,20 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
lower.indx[j++] = DatumGetInt32(ExecEvalExpr(eltstate,
econtext,
isNull,
&eisnull,
NULL));
/*
* If any index expr yields NULL, result is NULL or source
* array
*/
if (*isNull)
if (eisnull)
{
if (!isAssignment || array_source == NULL)
if (!isAssignment)
{
*isNull = true;
return (Datum) NULL;
*isNull = false;
}
return PointerGetDatum(array_source);
}
}
@ -321,25 +313,49 @@ ExecEvalArrayRef(ArrayRefExprState *astate,
if (isAssignment)
{
Datum sourceData = ExecEvalExpr(astate->refassgnexpr,
econtext,
isNull,
NULL);
Datum sourceData;
/*
* Evaluate the value to be assigned into the array.
*
* XXX At some point we'll need to look into making the old value of
* the array element available via CaseTestExpr, as is done by
* ExecEvalFieldStore. This is not needed now but will be needed
* to support arrays of composite types; in an assignment to a field
* of an array member, the parser would generate a FieldStore that
* expects to fetch its input tuple via CaseTestExpr.
*/
sourceData = ExecEvalExpr(astate->refassgnexpr,
econtext,
&eisnull,
NULL);
/*
* For now, can't cope with inserting NULL into an array, so make
* it a no-op per discussion above...
*/
if (eisnull)
return PointerGetDatum(array_source);
/*
* For an assignment, if all the subscripts and the input expression
* are non-null but the original array is null, then substitute an
* empty (zero-dimensional) array and proceed with the assignment.
* This only works for varlena arrays, though; for fixed-length
* array types we punt and return the null input array.
*/
if (*isNull)
{
if (array_source == NULL)
return (Datum) NULL;
*isNull = false;
return PointerGetDatum(array_source);
}
if (astate->refattrlength > 0) /* fixed-length array? */
return PointerGetDatum(array_source);
if (array_source == NULL)
return sourceData; /* XXX do something else? */
array_source = construct_md_array(NULL, 0, NULL, NULL,
arrayRef->refelemtype,
astate->refelemlength,
astate->refelembyval,
astate->refelemalign);
*isNull = false;
}
if (lIndex == NULL)
resultArray = array_set(array_source, i,
@ -2538,6 +2554,120 @@ ExecEvalFieldSelect(FieldSelectState *fstate,
return result;
}
/* ----------------------------------------------------------------
* ExecEvalFieldStore
*
* Evaluate a FieldStore node.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalFieldStore(FieldStoreState *fstate,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
FieldStore *fstore = (FieldStore *) fstate->xprstate.expr;
HeapTuple tuple;
Datum tupDatum;
TupleDesc tupDesc;
Datum *values;
char *nulls;
Datum save_datum;
bool save_isNull;
ListCell *l1,
*l2;
tupDatum = ExecEvalExpr(fstate->arg, econtext, isNull, isDone);
if (isDone && *isDone == ExprEndResult)
return tupDatum;
/* Lookup tupdesc if first time through or if type changes */
tupDesc = fstate->argdesc;
if (tupDesc == NULL ||
fstore->resulttype != tupDesc->tdtypeid)
{
MemoryContext oldcontext;
tupDesc = lookup_rowtype_tupdesc(fstore->resulttype, -1);
/* Copy the tupdesc into query storage for safety */
oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
tupDesc = CreateTupleDescCopy(tupDesc);
if (fstate->argdesc)
FreeTupleDesc(fstate->argdesc);
fstate->argdesc = tupDesc;
MemoryContextSwitchTo(oldcontext);
}
/* Allocate workspace */
values = (Datum *) palloc(tupDesc->natts * sizeof(Datum));
nulls = (char *) palloc(tupDesc->natts * sizeof(char));
if (!*isNull)
{
/*
* heap_deformtuple needs a HeapTuple not a bare HeapTupleHeader.
* We set all the fields in the struct just in case.
*/
HeapTupleHeader tuphdr;
HeapTupleData tmptup;
tuphdr = DatumGetHeapTupleHeader(tupDatum);
tmptup.t_len = HeapTupleHeaderGetDatumLength(tuphdr);
ItemPointerSetInvalid(&(tmptup.t_self));
tmptup.t_tableOid = InvalidOid;
tmptup.t_data = tuphdr;
heap_deformtuple(&tmptup, tupDesc, values, nulls);
}
else
{
/* Convert null input tuple into an all-nulls row */
memset(nulls, 'n', tupDesc->natts * sizeof(char));
}
/* Result is never null */
*isNull = false;
save_datum = econtext->caseValue_datum;
save_isNull = econtext->caseValue_isNull;
forboth(l1, fstate->newvals, l2, fstore->fieldnums)
{
ExprState *newval = (ExprState *) lfirst(l1);
AttrNumber fieldnum = lfirst_int(l2);
bool eisnull;
Assert(fieldnum > 0 && fieldnum <= tupDesc->natts);
/*
* Use the CaseTestExpr mechanism to pass down the old value of the
* field being replaced; this is useful in case we have a nested field
* update situation. It's safe to reuse the CASE mechanism because
* there cannot be a CASE between here and where the value would be
* needed.
*/
econtext->caseValue_datum = values[fieldnum - 1];
econtext->caseValue_isNull = (nulls[fieldnum - 1] == 'n');
values[fieldnum - 1] = ExecEvalExpr(newval,
econtext,
&eisnull,
NULL);
nulls[fieldnum - 1] = eisnull ? 'n' : ' ';
}
econtext->caseValue_datum = save_datum;
econtext->caseValue_isNull = save_isNull;
tuple = heap_formtuple(tupDesc, values, nulls);
pfree(values);
pfree(nulls);
return HeapTupleGetDatum(tuple);
}
/* ----------------------------------------------------------------
* ExecEvalRelabelType
*
@ -2810,6 +2940,18 @@ ExecInitExpr(Expr *node, PlanState *parent)
state = (ExprState *) fstate;
}
break;
case T_FieldStore:
{
FieldStore *fstore = (FieldStore *) node;
FieldStoreState *fstate = makeNode(FieldStoreState);
fstate->xprstate.evalfunc = (ExprStateEvalFunc) ExecEvalFieldStore;
fstate->arg = ExecInitExpr(fstore->arg, parent);
fstate->newvals = (List *) ExecInitExpr((Expr *) fstore->newvals, parent);
fstate->argdesc = NULL;
state = (ExprState *) fstate;
}
break;
case T_RelabelType:
{
RelabelType *relabel = (RelabelType *) node;