in src/kll_double_sketch_pg_functions.c [61:93]
Datum pg_kll_double_sketch_build_agg(PG_FUNCTION_ARGS) {
void* sketchptr;
double value;
int k;
MemoryContext oldcontext;
MemoryContext aggcontext;
if (PG_ARGISNULL(0) && PG_ARGISNULL(1)) {
PG_RETURN_NULL();
} else if (PG_ARGISNULL(1)) {
PG_RETURN_POINTER(PG_GETARG_POINTER(0)); // no update value. return unmodified state
}
if (!AggCheckCallContext(fcinfo, &aggcontext)) {
elog(ERROR, "kll_double_sketch_build_agg called in non-aggregate context");
}
oldcontext = MemoryContextSwitchTo(aggcontext);
if (PG_ARGISNULL(0)) {
k = PG_NARGS() > 2 ? PG_GETARG_INT32(2) : DEFAULT_K;
sketchptr = kll_double_sketch_new(k);
} else {
sketchptr = PG_GETARG_POINTER(0);
}
value = PG_GETARG_FLOAT8(1);
kll_double_sketch_update(sketchptr, value);
MemoryContextSwitchTo(oldcontext);
PG_RETURN_POINTER(sketchptr);
}