Method Read

src/leveldb/benchmarks/db_bench_sqlite3.cc:577–644

  }

  void Read(Order order, int entries_per_batch) {
    int status;
    sqlite3_stmt *read_stmt, *begin_trans_stmt, *end_trans_stmt;

    std::string read_str = "SELECT * FROM test WHERE key = ?";
    std::string begin_trans_str = "BEGIN TRANSACTION;";
    std::string end_trans_str = "END TRANSACTION;";

    // Preparing sqlite3 statements
    status = sqlite3_prepare_v2(db_, begin_trans_str.c_str(), -1,
                                &begin_trans_stmt, nullptr);
    ErrorCheck(status);
    status = sqlite3_prepare_v2(db_, end_trans_str.c_str(), -1, &end_trans_stmt,
                                nullptr);
    ErrorCheck(status);
    status = sqlite3_prepare_v2(db_, read_str.c_str(), -1, &read_stmt, nullptr);
    ErrorCheck(status);

    bool transaction = (entries_per_batch > 1);
    for (int i = 0; i < reads_; i += entries_per_batch) {
      // Begin read transaction
      if (FLAGS_transaction && transaction) {
        status = sqlite3_step(begin_trans_stmt);
        StepErrorCheck(status);
        status = sqlite3_reset(begin_trans_stmt);
        ErrorCheck(status);
      }

      // Create and execute SQL statements
      for (int j = 0; j < entries_per_batch; j++) {
        // Create key value
        char key[100];
        int k = (order == SEQUENTIAL) ? i + j : (rand_.Next() % reads_);
        snprintf(key, sizeof(key), "%016d", k);

        // Bind key value into read_stmt
        status = sqlite3_bind_blob(read_stmt, 1, key, 16, SQLITE_STATIC);
        ErrorCheck(status);

        // Execute read statement
        while ((status = sqlite3_step(read_stmt)) == SQLITE_ROW) {
        }
        StepErrorCheck(status);

        // Reset SQLite statement for another use
        status = sqlite3_clear_bindings(read_stmt);
        ErrorCheck(status);
        status = sqlite3_reset(read_stmt);
        ErrorCheck(status);
        FinishedSingleOp();
      }

      // End read transaction
      if (FLAGS_transaction && transaction) {
        status = sqlite3_step(end_trans_stmt);
        StepErrorCheck(status);
        status = sqlite3_reset(end_trans_stmt);
        ErrorCheck(status);