我研究过sqlite,只是想问: 简单数据库中素数文件中记录从一列开始的速度是4秒。可以吗还是我有一些软件/硬件问题? 在 SQLite 中写入超过 4 秒的 256 个注释(对于非 mysql 文件写入为 2 毫秒) 我简直不敢相信 sqlite 的写入速度这么慢。
我的比较 sqlite 数据库工作和文件数据库工作的代码:
package demo_SQLite;
import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
public class demo_SQLite {
private static Connection conn;
private static Statement state;
private static File db = new File("datafile");
public static void main(String[] args) throws IOException {
Debug("Start DB!");
run();
}
private static void run() throws IOException {
try {
if (!db.exists()) {
db.createNewFile();
}
Class.forName("org.sqlite.JDBC");
conn = DriverManager.getConnection("jdbc:sqlite:" + db);
state = conn.createStatement();
state.executeUpdate("create table if not exists a(id integer,"
+ "time INT,"
+ "primary key (id));");
PreparedStatement prep = conn.prepareStatement("insert into a values(?,?)");
for (int i = 0; i < 257; i++) {
int l = new Random().nextInt();
prep.setInt(2, l);
prep.execute();
}
prep.close();
state.close();
Debug("Done! (256)");
file();
} catch (Exception ex) {
Logger.getLogger(Demo_MySQL.class.getName()).log(Level.SEVERE, null, ex);
}
}
private static void file() {
try {
Debug("Start File!");
File file = new File("filebase");
DataOutputStream dos = null;
dos = new DataOutputStream
(new BufferedOutputStream(new FileOutputStream(file)));
int r = 0;
for (int i = 0; i < 257; ++i) {
r = new Random().nextInt();
dos.writeInt(r);
}
dos.flush();
dos.close();
Debug("Done! (256)");
} catch (IOException ex) {
Logger.getLogger(Demo_MySQL.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void Debug(String msg) {
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss.SSS");
Date date = new Date();
System.out.println("[" + sdf.format(date) + "][DEBUG]: " + msg);
}
}
结果:
run:
[07:53:49.829][DEBUG]: Start DB!
[07:53:53.223][DEBUG]: Done! (256)
[07:53:53.223][DEBUG]: Start File!
[07:53:53.253][DEBUG]: Done! (256)
BUILD SUCCESSFUL (total time: 5 seconds)
4秒!哇!这很棒! 请告诉我 - 这是正常的还是我做错了什么?
已更新。
似乎自动提交有问题。正如我刚才在某处读到的那样,“默认情况下,每个 INSERT 语句都是它自己的事务。但是如果您用 BEGIN...COMMIT 包围多个 INSERT 语句,那么所有插入都会分组到单个事务中。提交事务所需的时间分摊到所有包含的插入语句上,因此每个插入语句的时间大大减少。”
我刚刚禁用了自动提交 - 更正后的代码和新结果:
package demo_sqlite;
import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;
public class demo_SQLite {
private static Connection conn;
private static Statement state;
private static File db = new File("datafile");
public static void main(String[] args) throws IOException {
Debug("Start DB!");
run();
}
private static void run() throws IOException {
try {
if (!db.exists()) {
db.createNewFile();
}
//run db driver
Class.forName("org.sqlite.JDBC");
conn = DriverManager.getConnection("jdbc:sqlite:" + db);
state = conn.createStatement();
//check table
state.executeUpdate("create table if not exists a(id integer,"
+ "time INT,"
+ "primary key (id));");
conn.setAutoCommit(false);
// clear table if table not clear
state.execute("DELETE FROM a");
conn.commit();
//make needed notes for db
PreparedStatement prep = conn.prepareStatement("insert into a values(?,?)");
for (int i = 0; i < 256; ++i) {
int l = new Random().nextInt();
prep.setInt(2, l);
prep.execute();
}
conn.commit();
prep.close();
//reading notes for chek
List<Integer> notes = new LinkedList<Integer>();
ResultSet res = state.executeQuery("select * from a");
while (res.next()) { int n = res.getInt("time"); notes.add(n); }
res.close();
state.close();
Debug("Done! ("+ notes.size() + ")");
//write to a file for comparing the write speed
Debug("Start File!");
File file = new File("filebase");
DataOutputStream dos = null;
dos = new DataOutputStream
(new BufferedOutputStream(new FileOutputStream(file)));
int r = 0;
for (int i = 0; i < 256; ++i) {
r = new Random().nextInt();
dos.writeInt(r);
}
dos.flush();
dos.close();
Debug("Done! (256)");
//done! see log for result
} catch (Exception ex) { }
}
public static void Debug(String msg) {
SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss.SSS");
Date date = new Date();
System.out.println("[" + sdf.format(date) + "][DEBUG]: " + msg);
}
}
结果:
run:
[09:01:36.890][DEBUG]: Start DB!
[09:01:37.052][DEBUG]: Done! (256)
[09:01:37.053][DEBUG]: Start File!
[09:01:37.054][DEBUG]: Done! (256)
BUILD SUCCESSFUL (total time: 0 seconds)
谢谢大家的解答!但如果您对此有一些考虑,请欢迎
最佳答案
我可能会尝试不同的驱动程序。尝试一下 mySQL 附带的一个: http://www.mysql.com/products/connector/
The name of the class that implements java.sql.Driver in MySQL Connector/J is com.mysql.jdbc.Driver.
关于java - SQLite 写入速度非常慢,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24618828/