Datum pg_hll_sketch_union_agg()

in src/hll_sketch_pg_functions.c [126:168]

• 36 lines of code
• 12 McCabe index (conditional complexity)

Datum pg_hll_sketch_union_agg(PG_FUNCTION_ARGS) {
  struct hll_agg_state* stateptr;
  bytea* sketch_bytes;
  void* sketchptr;

  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, "hll_sketch_union_agg called in non-aggregate context");
  }
  oldcontext = MemoryContextSwitchTo(aggcontext);

  if (PG_ARGISNULL(0)) {
    stateptr = palloc(sizeof(struct hll_agg_state));
    stateptr->type = UNION;
    stateptr->lg_k = PG_NARGS() > 2 ? PG_GETARG_INT32(2) : HLL_DEFAULT_LG_K;
    stateptr->tgt_type = PG_NARGS() > 3 ? PG_GETARG_INT32(3) : 0;
    if (stateptr->tgt_type) {
      if ((stateptr->tgt_type != 4) && (stateptr->tgt_type != 6) && (stateptr->tgt_type != 8)) {
        elog(ERROR, "hll_sketch_union_agg: unsupported target type, must be 4, 6 or 8");
      }
    }
    stateptr->ptr = hll_union_new(stateptr->lg_k);
  } else {
    stateptr = (struct hll_agg_state*) PG_GETARG_POINTER(0);
  }

  sketch_bytes = PG_GETARG_BYTEA_P(1);
  sketchptr = hll_sketch_deserialize(VARDATA(sketch_bytes), VARSIZE(sketch_bytes) - VARHDRSZ);
  hll_union_update(stateptr->ptr, sketchptr);
  hll_sketch_delete(sketchptr);

  MemoryContextSwitchTo(oldcontext);

  PG_RETURN_POINTER(stateptr);
}