Github user cwelton commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/10#discussion_r49820902
--- Diff: methods/array_ops/src/pg_gp/array_ops.c ---
@@ -824,6 +836,25 @@ array_fill(PG_FUNCTION_ARGS){
}
/*
+ * This function apply cos function to each element.
+ */
+PG_FUNCTION_INFO_V1(array_cos);
+Datum
+array_cos(PG_FUNCTION_ARGS){
+ if (PG_ARGISNULL(0)) { PG_RETURN_NULL(); }
+
+ ArrayType *v1 = PG_GETARG_ARRAYTYPE_P(0);
+ Oid element_type = ARR_ELEMTYPE(v1);
+ Datum v2 = float8_datum_cast(0, element_type);
+
+ ArrayType *res = General_Array_to_Array(v1, v2, element_cos);
+
+ PG_FREE_IF_COPY(v1, 0);
--- End diff --
In answer to your question, you can think of the parameter that is being
received as a union between (toastid, text_pointer). If you receive a pointer
then you do not get a copy, if you get a toastid then the GET_ARRAY_TYPE
function will detoast it and return a pointer to you. In neither case do you
"get a copy" of a pointer that was passed as input, which is what led to the
initial confusion here - "free_if_copy" is a misleading name for the macro.
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