From 5b9453bcd3b28561c33495199c61c81994c58398 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 14 Nov 2008 00:12:08 +0000
Subject: [PATCH] Minor code clarity improvements in array_agg functions, and
add a comment about how this is playing fast and loose with the type system.
---
src/backend/utils/adt/array_userfuncs.c | 42 +++++++++++++++++++------
1 file changed, 33 insertions(+), 9 deletions(-)
diff --git a/src/backend/utils/adt/array_userfuncs.c b/src/backend/utils/adt/array_userfuncs.c
index 4eeb64dbd8..6f18c66405 100644
--- a/src/backend/utils/adt/array_userfuncs.c
+++ b/src/backend/utils/adt/array_userfuncs.c
@@ -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));
}
--
2.40.0