Datum pg_hll_sketch_build_agg()

in src/hll_sketch_pg_functions.c [66:124]

• 47 lines of code
• 14 McCabe index (conditional complexity)

Datum pg_hll_sketch_build_agg(PG_FUNCTION_ARGS) {
  struct hll_agg_state* stateptr;

  // anyelement
  Oid   element_type;
  Datum element;
  int16 typlen;
  bool  typbyval;
  char  typalign;

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

  if (PG_ARGISNULL(0)) {
    stateptr = palloc(sizeof(struct hll_agg_state));
    stateptr->type = SKETCH;
    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_build_agg: unsupported target type, must be 4, 6 or 8");
      }
      stateptr->ptr = hll_sketch_new_tgt_type(stateptr->lg_k, stateptr->tgt_type);
    } else {
      stateptr->ptr = hll_sketch_new(stateptr->lg_k);
    }
  } else {
    stateptr = (struct hll_agg_state*) PG_GETARG_POINTER(0);
  }

  element_type = get_fn_expr_argtype(fcinfo->flinfo, 1);
  element = PG_GETARG_DATUM(1);
  get_typlenbyvalalign(element_type, &typlen, &typbyval, &typalign);
  if (typlen == -1) {
    // varlena
    hll_sketch_update(stateptr->ptr, VARDATA_ANY(element), VARSIZE_ANY_EXHDR(element));
  } else if (typbyval) {
    // fixed-length passed by value
    hll_sketch_update(stateptr->ptr, &element, typlen);
  } else {
    // fixed-length passed by reference
    hll_sketch_update(stateptr->ptr, (void*)element, typlen);
  }

  MemoryContextSwitchTo(oldcontext);

  PG_RETURN_POINTER(stateptr);
}