Mysql怎么确定储存过程是预编译的比普通sql执行的快

发布网友发布时间：2022-04-30 19:19

共2个回答

懂视网时间：2022-04-30 23:40

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：

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

标签：

热心网友时间：2022-04-30 20:48

SET @update_stmt='' /*在单引号中间填入要执行的sql语句*/
PREPARE stmt FROM @update_stmt;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;