测试mysql的sql语句预编译效果

package exmysql; 2 3 import java.sql.Connection; 4 import java.sql.DriverManager; 5 import java.sql.ResultSet; 6 import java.sql.SQLException; 7 import java.sql.Statement; 8 import java.util.Date; 9 10 public class adddata { 11 12 private static long worker(){ 13 Date begin = new Date(); 14 15 String driver="com.mysql.jdbc.Driver"; 16 17 String url="jdbc:mysql://172.16.2.7:3306/testdb"; 18 19 Connection conn=null; 20 Statement stmt=null; 21 ResultSet rs=null; 22 23 try{ 24 Class.forName(driver); 25 conn=DriverManager.getConnection(url,"dbaadmin","123456"); 26 stmt=conn.createStatement(); 27 String sql; 28 for (int i=1;i<=5000;i++){ 29 sql="select * from test1 where id="+i; 30 rs=stmt.executeQuery(sql); 31 } 32 } 33 catch(SQLException | ClassNotFoundException e){ 34 e.printStackTrace(); 35 } 36 37 if(stmt!=null){ 38 try{ 39 stmt.close(); 40 } 41 catch(SQLException e){ 42 e.printStackTrace(); 43 } 44 } 45 46 if(conn!=null){ 47 try{ 48 conn.close(); 49 } 50 catch(SQLException e){ 51 e.printStackTrace(); 52 } 53 } 54 55 Date end = new Date(); 56 return end.getTime()-begin.getTime(); 57 } 58 59 public static void main(String[] args) { 60 // TODO Auto-generated method stub 61 62 long elapsed,average; 63 average=0; 64 for (int i=1;i<=10;i++){ 65 elapsed=worker(); 66 System.out.println("elapsed time(ms):"+elapsed); 67 average=average+elapsed; 68 } 69 System.out.println("average time(ms):"+average/10); 70 } 71 72 }

结果如下：

elapsed time(ms):24652
elapsed time(ms):13380
elapsed time(ms):13250
elapsed time(ms):13877
elapsed time(ms):13275
elapsed time(ms):13193
elapsed time(ms):19022
elapsed time(ms):13558
elapsed time(ms):14138
elapsed time(ms):13364
average time(ms):15170

 

2.同样的sql用PreparedStatement预编译执行

 

 1 package exmysql;
 2 
 3 import java.sql.*;
 4 import java.util.Date;
 5 
 6 public class insert_data {
 7 
 8     private static long worker(){
 9         Date begin = new Date(); 
10         
11         String driver="com.mysql.jdbc.Driver";
12 
13         String url="jdbc:mysql://172.16.2.7:3306/testdb";
14         
15         Connection conn=null;
16         PreparedStatement pstm=null;
17         ResultSet rs=null;
18         
19         try{
20             Class.forName(driver);
21             conn=DriverManager.getConnection(url,"dbaadmin","123456");
22             conn.setAutoCommit(false);
23             String sql="select * from test1 where id=?";
24             pstm=conn.prepareStatement(sql);
25             for(int i=1;i<=5000;i++){
26                 pstm.setInt(1, i);
27                 rs=pstm.executeQuery();
28             }
29             conn.commit();
30             
31         }
32         catch(SQLException | ClassNotFoundException e){
33             e.printStackTrace();
34         }
35         
36         if(pstm!=null){
37             try{
38                 pstm.close();
39             }
40             catch(SQLException e){
41                 e.printStackTrace();
42             }
43         }
44         
45         if(conn!=null){
46             try{
47                 conn.close();
48             }
49             catch(SQLException e){
50                 e.printStackTrace();
51             }
52         }
53         
54         Date end = new Date(); 
55         return end.getTime()-begin.getTime();
56     }
57     
58     public static void main(String[] args) {
59         // TODO Auto-generated method stub
60         
61         long elapsed,average;
62         average=0;
63         for (int i=1;i<=10;i++){
64             elapsed=worker();
65             System.out.println("elapsed time(ms):"+elapsed);
66             average=average+elapsed;
67         }
68         System.out.println("average time(ms):"+average/10);
69     }
70 
71 }

结果如下：

elapsed time(ms):14773
elapsed time(ms):16352
elapsed time(ms):14797
elapsed time(ms):15800
elapsed time(ms):12069
elapsed time(ms):14953
elapsed time(ms):13238
elapsed time(ms):12366
elapsed time(ms):15263
elapsed time(ms):13089
average time(ms):14270

 

可以看出两种方式执行的结果几乎相同，不像Oracle差距那么大。而且就算是用PreparedStatement的方式，在Mysql数据库端抓出来的sql语句也不是以变量id=?的形式出现的，而是实际的数值。后来在网上看到在连接字符串上加上useServerPrepStmts=true可以实现真正的预编译

        String url="jdbc:mysql://172.16.2.7:3306/testdb";
        url=url+"?useServerPrepStmts=true";

加上这段后可以在数据库端可以看到明确的结果：

mysql> show global status like ‘Com_stmt_prepare‘;
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| Com_stmt_prepare | 11 |
+------------------+-------+
1 row in set (0.00 sec)

 

但是实际的运行结果和上面几乎一样，性能上没有任何的提升。由此可以推断出Mysql由于缺少类似于Oracle的library cache的部件，因此采用预编译方式执行sql是没有性能上的提升的。

 

测试mysql的sql语句预编译效果

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