Java SQL 优化

Question

我正在尝试将 SQL 数据库与 Java 程序一起使用。我制作了一个 7 列宽和 250 万行的表(我需要构建的下一个表大约有 2 亿行)。我有两个问题:构建 SQL 表太慢(大约 2,000 行/分钟)和搜索数据库太慢(如果可能的话，我需要在一秒钟内找到超过 1 亿行，目前需要一分钟以上)。我试过创建一个 csv 文件并导入它，但是 I can't get it to work 。

我在我的电脑上使用 xampp 和 phpMyAdmin (i5 + 6gb ram)。我正在测试三种方法:createTable()、writeSQL() 和 searchSQL()。

创建表:

public static void createTable() {
    String driverName = "org.gjt.mm.mysql.Driver";
    Connection connection = null;
    try {
        Class.forName(driverName);

    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    String serverName = "localhost";
    String mydatabase = "PokerRanks4";
    String url = "jdbc:mysql://" + serverName + "/" + mydatabase;                                                                        
    String username = "root";
    String password = "";

    try {
        connection = DriverManager.getConnection(url, username, password);
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    ///////////////
    String table = "CREATE TABLE ranks(deckForm bigint(10) NOT NULL,rank0 int(2) NOT NULL,rank1 int(2) NOT NULL,rank2 int(2) NOT NULL,rank3 int(2) NOT NULL,rank4 int(2) NOT NULL,rank5 int(2) NOT NULL,PRIMARY KEY (deckForm),UNIQUE id (deckForm),KEY id_2 (deckForm))";
    try {
        Statement st = connection.createStatement();
        st.executeUpdate(table);
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    ///////////////

    try {
        connection.close();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

writeSQL():

public static void writeSQL() {
    String driverName = "org.gjt.mm.mysql.Driver";
    Connection connection = null;
    try {
        Class.forName(driverName);

    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    String serverName = "localhost";
    String mydatabase = "PokerRanks4";
    String url = "jdbc:mysql://" + serverName + "/" + mydatabase;                                                                        
    String username = "root";
    String password = "";

    try {
        connection = DriverManager.getConnection(url, username, password);
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }


    /////////////// Prepared Statement with Batch   
    PreparedStatement statement = null;
    String sql = "INSERT INTO ranks VALUES (? ,0, 0, 0, 0, 0, 0)";      
    long start = System.currentTimeMillis();
    try {
        statement = connection.prepareStatement(sql);
        for (int i = 0; i < 100; i++) {
            for (int j = 0; j < 100; j++) {
                statement.setLong(1, (i*100 + j));
                statement.addBatch();
            }
            System.out.println(i);
            statement.executeBatch();
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
      if (statement != null) {
        try {
          statement.close();
        } catch (SQLException e) {
        } // nothing we can do
      }
      if (connection != null) {
        try {
          connection.close();
        } catch (SQLException e) {
        } // nothing we can do
      }       
    }
    System.out.println("Total Time: " + (System.currentTimeMillis() - start) / 1000 );
    ///////////////

}

搜索SQL():

public static void searchSQL() {
    String driverName = "org.gjt.mm.mysql.Driver";
    Connection connection = null;
    try {
        Class.forName(driverName);

    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    String serverName = "localhost";
    String mydatabase = "PokerRanks2";
    String url = "jdbc:mysql://" + serverName + "/" + mydatabase;                                                                        
    String username = "root";
    String password = "";

    try {
        connection = DriverManager.getConnection(url, username, password);
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }



    /////////////// Option 1, Prepared Statement
    ResultSet rs = null;
    PreparedStatement pstmt = null;
    String query = "SELECT rank0, rank1, rank2, rank3, rank4, rank5 FROM ranks WHERE deckForm = ?";
    long start = System.currentTimeMillis();
    try {
        pstmt = connection.prepareStatement(query);             
        for (int i = 0; i < 100000; i++) {              
            pstmt.setLong(1, 1423354957);
            rs = pstmt.executeQuery();
            while (rs.next()) {             
                int[] arr = {rs.getInt(1), rs.getInt(2), rs.getInt(3), rs.getInt(4), rs.getInt(5), rs.getInt(6)};               
            }
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }                       
    System.out.println("Total Time: " + (System.currentTimeMillis() - start) / 1000 );
    ///////////////

    /*
    /////////////// Option 2
    Statement st = null;
    long start = System.currentTimeMillis(); 
    try {
        st = connection.createStatement();
        ResultSet rs = null;
        long deckForm = 1012213456;             
        for (int i = 0; i < 100000; i++) {          
            rs = st.executeQuery("SELECT rank0, rank1, rank2, rank3, rank4, rank5 FROM ranks WHERE deckForm = " + deckForm);
            while (rs.next()) {
                int[] arr = {rs.getInt(1), rs.getInt(2), rs.getInt(3), rs.getInt(4), rs.getInt(5), rs.getInt(6)}; 
            }
        }
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }        
    System.out.println("Total Time: " + (System.currentTimeMillis() - start) / 1000 );
    ///////////////
    */


    try {
        connection.close();
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

抱歉，这么长。我已经尝试了所有我能想到的来使它更快，但我无法弄清楚。有什么建议吗？

Answer 1

好吧，您可以做一些改进:

1. 每次你想要搜索、写作或创建时，你都在创建一个连接， 您应该使用共用连接和数据源。
2. 通过解释计划优化您的查询，并优化您的表关系和索引。
3. 您可以使用存储过程并调用它们。

我能帮上的就这些了，当然还有更多提示。