in src/theta_sketch_pg_functions.c [157:189]
Datum pg_theta_sketch_intersection_agg(PG_FUNCTION_ARGS) {
struct agg_state* stateptr;
bytea* sketch_bytes;
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, "theta_sketch_intersection_agg called in non-aggregate context");
}
oldcontext = MemoryContextSwitchTo(aggcontext);
if (PG_ARGISNULL(0)) {
stateptr = palloc(sizeof(struct agg_state));
stateptr->type = INTERSECTION;
stateptr->ptr = theta_intersection_new_default();
} else {
stateptr = (struct agg_state*) PG_GETARG_POINTER(0);
}
sketch_bytes = PG_GETARG_BYTEA_P(1);
theta_intersection_update_with_bytes(stateptr->ptr, VARDATA(sketch_bytes), VARSIZE(sketch_bytes) - VARHDRSZ);
MemoryContextSwitchTo(oldcontext);
PG_RETURN_POINTER(stateptr);
}