Datum pg_frequent_strings_sketch_merge_agg()

in src/frequent_strings_sketch_pg_functions.c [92:127]

• 29 lines of code
• 6 McCabe index (conditional complexity)

Datum pg_frequent_strings_sketch_merge_agg(PG_FUNCTION_ARGS) {
  void* unionptr;
  bytea* sketch_bytes;
  void* sketchptr;
  unsigned lg_k;

  MemoryContext oldcontext;
  MemoryContext aggcontext;

  if (PG_ARGISNULL(0) && PG_ARGISNULL(2)) {
    PG_RETURN_NULL();
  } else if (PG_ARGISNULL(2)) {
    PG_RETURN_POINTER(PG_GETARG_POINTER(0)); // no update value. return unmodified state
  }

  if (!AggCheckCallContext(fcinfo, &aggcontext)) {
    elog(ERROR, "frequent_strings_sketch_merge_agg called in non-aggregate context");
  }
  oldcontext = MemoryContextSwitchTo(aggcontext);

  if (PG_ARGISNULL(0)) {
    lg_k = PG_GETARG_INT32(1);
    unionptr = frequent_strings_sketch_new(lg_k);
  } else {
    unionptr = PG_GETARG_POINTER(0);
  }

  sketch_bytes = PG_GETARG_BYTEA_P(2);
  sketchptr = frequent_strings_sketch_deserialize(VARDATA(sketch_bytes), VARSIZE(sketch_bytes) - VARHDRSZ);
  frequent_strings_sketch_merge(unionptr, sketchptr);
  frequent_strings_sketch_delete(sketchptr);

  MemoryContextSwitchTo(oldcontext);

  PG_RETURN_POINTER(unionptr);
}