// How fast can we insert 62 million “records” into LevelDB?
// This program does it in 3'24" on my laptop (a four-core 1.6GHz
// N3700 with a 100-gigabyte 50-megabyte-per-second SSD), which works
// out to 304 kilorecords per second.  The ultimately resulting
// LevelDB is 516 megabytes, for 8.3 bytes per record and 2.5
// megabytes per second, though some of this is fixed transaction log
// overhead.
#include <cstdlib>
#include <iostream>
#include <string>
#include <leveldb/db.h>
#include <leveldb/write_batch.h>

using leveldb::DB;
using leveldb::Options;
using leveldb::WriteOptions;
using leveldb::WriteBatch;
using leveldb::Status;
using std::cerr;
using std::endl;
using std::string;
using std::to_string;           // C++11; g++ -std=c++11

const int batchSize = 2000;

int main(int argc, char **argv) {
  DB *db = 0;
  Options options;
  options.create_if_missing = true;
  Status s = DB::Open(options, "62m.tmp.db", &db);
  string sk = "k";
  string sv = "v";

  for (int i = 0; i < 62*1000*1000; i += batchSize) {
    if (s.ok()) {
      WriteBatch batch;

      for (int j = 0; j != batchSize; ++j) {
        string is = to_string(i + j);
        batch.Put(sk + is, sv + is);
      }

      s = db->Write(WriteOptions(), &batch);
    }
  }

  delete db;         // I should really be using a smart pointer, huh?

  if (!s.ok()) {
    cerr << s.ToString() << endl;
    return -1;
  }
  return 0;
}