插入從選擇查詢中檢索到的MySQL結果集？

Question

我在服務器x和服務器y上都有一個MySQL數據庫。

我試圖讓從表中的記錄叫testx這是位於服務器X和INSERT他們到一個名為暴躁表。 因此，我執行了SELECT語句並將其存儲到resultset集中。 然后，我試圖在resultset while循環中迭代INSERT語句。 這是我的示例代碼：

private static void cloneTableAndAlter() throws ClassNotFoundException, SQLException, InstantiationException, IllegalAccessException, InterruptedException {
        Connection connForSource = getConnectionForSource();
        Connection connForTarget = getConnectionForTarget();

        if (connForSource != null && connForTarget != null) {
            try {
                Statement st = connForSource.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY,
                        java.sql.ResultSet.CONCUR_READ_ONLY);

                String selectStatement = "SELECT field1, field2 FROM dbx.testx where time between ('2016-09-01 00:00:00') and ('2016-09-03 23:59:59');";

                String insertStatement = "INSERT INTO testy(" + "field1," + "field2)" + 
                        "VALUES(?,?) " +
                        "ON DUPLICATE KEY UPDATE field1 = VALUES(field1);"; <----field1 is a unique key but not primary

                st.setFetchSize(Integer.MIN_VALUE);

                ResultSet resultSetForSelect = st.executeQuery(selectStatement);
                PreparedStatement preparedStatement = connForTarget.prepareStatement(insertStatement);
                int count = 0;
                while (resultSetForSelect.next()) {
                    ++count;
                    TableDetails tableDetails = setTableDetails(resultSetForSelect); <--- i'm getting the value from the resultset and setting it to my DTO class.
                    getTableDetails(preparedStatement, tableDetails); <--- setting the values back during the insert from the DTO
                    preparedStatement.executeUpdate();
                    System.out.println(count + "rows affected");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

注意 ：源表（ testx ）有超過一百萬條記錄。

我可以插入，但是我感覺插入有點慢，每秒可以插入45-50次。 我要去哪里？

有什么方法可以優化此操作並增加插入量，或者這是插入大數據集的本質嗎？

任何幫助，不勝感激。

Answer 1

您可以采用其他方式：

使用此Concat創建一個Select

select GROUP_CONCAT(
    CONCAT(" ('",field1,"','",field2,"')")) as vals
from my_table;

結果看起來像這樣：

結果

mysql> select GROUP_CONCAT(
    -> CONCAT(" ('",field1,"','",field2,"')")) as vals
    -> from my_table;
+---------------------------------------------------------------------------------------------------------+
| vals                                                                                                    |
+---------------------------------------------------------------------------------------------------------+
|  ('O1','AC'), ('O1','PT'), ('O2','PT'), ('O3','MI'), ('O3','PT'), ('O4','EG'), ('O4','PT'), ('O5','PT') |
+---------------------------------------------------------------------------------------------------------+
1 row in set (0,00 sec)

mysql>

您可以直接在insert語句中進行連接，而您只能讀取一行並且只能編寫和執行一條語句。

您的密碼

    String selectStatement = "SELECT GROUP_CONCAT(CONCAT(" ('",field1,"','",field2,"')")) as vals
         FROM dbx.testx where time between ('2016-09-01 00:00:00') and ('2016-09-03 23:59:59');";

    ResultSet resultSetForSelect = st.executeQuery(selectStatement);


    String insertStatement = "INSERT INTO testy(" + "field1," + "field2)" + 
                            + String from result +
                            "ON DUPLICATE KEY UPDATE field1 = VALUES(field1);"; <----field1 is a unique key but not primary


# execute one time