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Minor code clarity improvements in array_agg functions, and add a comment

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about how this is playing fast and loose with the type system.
This commit is contained in:
Tom Lane 2008-11-14 00:12:08 +00:00
parent c23b6fa7b5
commit 5b9453bcd3
1 changed files with 33 additions and 9 deletions
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42
src/backend/utils/adt/array_userfuncs.c
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@ -6,7 +6,7 @@
* Copyright (c) 2003-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.24 2008/11/13 15:59:50 petere Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/array_userfuncs.c,v 1.25 2008/11/14 00:12:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -467,33 +467,57 @@ create_singleton_array(FunctionCallInfo fcinfo,
typlen, typbyval, typalign);
}
/*
* ARRAY_AGG aggregate function
*/
Datum
array_agg_transfn(PG_FUNCTION_ARGS)
{
Oid arg1_typeid = get_fn_expr_argtype(fcinfo->flinfo, 1);
ArrayBuildState *state;
Datum elem;
if (arg1_typeid == InvalidOid)
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not determine input data type")));
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not determine input data type")));
/* cannot be called directly because of internal-type argument */
Assert(fcinfo->context && IsA(fcinfo->context, AggState));
PG_RETURN_POINTER(accumArrayResult(PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0),
PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1),
PG_ARGISNULL(1),
arg1_typeid,
((AggState *) fcinfo->context)->aggcontext));
state = PG_ARGISNULL(0) ? NULL : (ArrayBuildState *) PG_GETARG_POINTER(0);
elem = PG_ARGISNULL(1) ? (Datum) 0 : PG_GETARG_DATUM(1);
state = accumArrayResult(state,
elem,
PG_ARGISNULL(1),
arg1_typeid,
((AggState *) fcinfo->context)->aggcontext);
/*
* We cheat quite a lot here by assuming that a pointer datum will be
* preserved intact when nodeAgg.c thinks it is a value of type "internal".
* This will in fact work because internal is stated to be pass-by-value
* in pg_type.h, and nodeAgg will never do anything with a pass-by-value
* transvalue except pass it around in Datum form. But it's mighty
* shaky seeing that internal is also stated to be 4 bytes wide in
* pg_type.h. If nodeAgg did put the value into a tuple this would
* crash and burn on 64-bit machines.
*/
PG_RETURN_POINTER(state);
}
Datum
array_agg_finalfn(PG_FUNCTION_ARGS)
{
ArrayBuildState *state;
/* cannot be called directly because of internal-type argument */
Assert(fcinfo->context && IsA(fcinfo->context, AggState));
if (PG_ARGISNULL(0))
PG_RETURN_NULL(); /* returns null iff no input values */
PG_RETURN_ARRAYTYPE_P(makeArrayResult((ArrayBuildState *) PG_GETARG_POINTER(0), CurrentMemoryContext));
state = (ArrayBuildState *) PG_GETARG_POINTER(0);
PG_RETURN_ARRAYTYPE_P(makeArrayResult(state, CurrentMemoryContext));
}