要讨论如何恢复从库,我们得先来了解如下一些概念:
GTID_EXECUTED:它是一组包含已经记录在二进制日志文件中的事务集合
GTID_PURGED:它是一组包含已经从二进制日志删除掉的事务集合。
 
 
在继续讨论时,我们先来看下如何新建一个基于GTID的slave。
通过了解上面的两个参数,我们现在只需要:
1.从主库上做一个备份时记录备份时gtid_executed的值。
2.在新的slave上恢复此备份时设置从库的gtid_purged的值为备份时master上gtid_executed的值。
 
通过mysqldump可以完成我们需要的功能。
 
 
目前主库上的状态(3301):
[zejin] 3301>show global variables like 'gtid_executed';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_executed | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-15 |
+---------------+-------------------------------------------+
1 row in set (0.00 sec) [zejin] 3301>show global variables like 'gtid_purged';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_purged | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-13 |
+---------------+-------------------------------------------+
1 row in set (0.00 sec)
 
 
step1:用mysqldump做一个全备
mysqldump --all-databases --single-transaction --triggers --routines --events --host=127.0.0.1 --port=3301 --user=root --password=123 > dump3301.sql
 
打开dump3301.sql我们可以看到如下语句:
SET @@GLOBAL.GTID_PURGED='a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-15';
此值即为master3301上gtid_executed的值。
 
step2:全新启动一个新的库3303,注意在配置文件中配置enforce_gtid_consistency及gtid_mode=on
mysqld_safe --defaults-file=/home/mysql/my3303.cnf &
此时新库3303上的状态应该是这样的: [(none)] 3303>show global variables like 'gtid_executed';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| gtid_executed | |
+---------------+-------+
1 row in set (0.01 sec) [(none)] 3303>show global variables like 'gtid_purged';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| gtid_purged | |
+---------------+-------+
1 row in set (0.00 sec)
 
step3:导入备份文件并查看状态值:
mysql -uroot -h127.0.0.1 -p123 -P3303 < dump3301.sql
[(none)] 3303>show global variables like 'gtid_executed';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_executed | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-15 |
+---------------+-------------------------------------------+
1 row in set (0.02 sec) [(none)] 3303>show global variables like 'gtid_purged';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_purged | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-15 |
+---------------+-------------------------------------------+
1 row in set (0.00 sec)
 
 
step4:做主从change语句
[zejin] 3303>change master to master_host='192.168.1.240',master_port=3301,master_user='repl',master_password='123',master_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.01 sec) [zejin] 3303>start slave;
Query OK, 0 rows affected (0.00 sec) [zejin] 3303>show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.240
Master_User: repl
Master_Port: 3301
Connect_Retry: 60
Master_Log_File: binlog57.000014
Read_Master_Log_Pos: 194
Relay_Log_File: zejin240-relay-bin.000002
Relay_Log_Pos: 365
Relay_Master_Log_File: binlog57.000014
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 194
Relay_Log_Space: 575
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3301
Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f
Master_Info_File: /home/mysql/I3303/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-15
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
 
至此完成了加入一台新的slave的GTID主从环境。
 
 
假如我们目前拥有一主带两从的环境:
master(3301)
slave(3302)
slave(3303)
 
我们来考虑这么一种异常情况,由于种种原因,有可能主库上已经purge掉了一些binlog,但从库都还没有接收到(如slave停了一段时间,而master已经把一些binlog给purge掉了。)
 
主库目前的状态是:
[zejin] 3301>show global variables like 'gtid_executed';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_executed | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-21 |
+---------------+-------------------------------------------+
1 row in set (0.00 sec) [zejin] 3301>show global variables like 'gtid_purged';
+---------------+-------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------+
| gtid_purged | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-20 |
+---------------+-------------------------------------------+
1 row in set (0.00 sec) [zejin] 3301>select * from t_users;
+----+------+
| id | name |
+----+------+
| 1 | chen |
| 2 | ok |
| 3 | li |
+----+------+
3 rows in set (0.00 sec)

在从库3303上,我们可以看到如下错误提示:

Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.'
[zejin] 3303>show slave status\G
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.1.240
Master_User: repl
Master_Port: 3301
Connect_Retry: 60
Master_Log_File: binlog57.000014
Read_Master_Log_Pos: 457
Relay_Log_File: zejin240-relay-bin.000003
Relay_Log_Pos: 4
Relay_Master_Log_File: binlog57.000014
Slave_IO_Running: No
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 457
Relay_Log_Space: 194
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 1236
Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.'
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3301
Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f
Master_Info_File: /home/mysql/I3303/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp: 160809 17:25:39
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:16
Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-16
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec) [zejin] 3303>select * from t_users;
+----+------+
| id | name |
+----+------+
| 1 | li |
| 2 | zhou |
+----+------+
2 rows in set (0.00 sec)
主从已经中断,数据也已不一致。
 
接下来我们来看如何恢复:
由于GTID具有全局唯一性,那么其它正常的gtid已经被复制到了slave3302上,所以我们可以把3303指向3302,同步完毕后再指回master3301(此前提基于3302的binlog还没被purge掉,即存在3303没有从master3301接收到的GTID事务)
操作方法如下:
[zejin] 3303>change master to master_host='192.168.1.240',master_port=3302,master_user='repl',master_password='',master_auto_position=1;

[zejin] 3303>start slave;
Query OK, 0 rows affected (0.03 sec) [zejin] 3303>show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.240
Master_User: repl
Master_Port: 3302
Connect_Retry: 60
Master_Log_File: binlog57.000007
Read_Master_Log_Pos: 1723
Relay_Log_File: zejin240-relay-bin.000002
Relay_Log_Pos: 1687
Relay_Master_Log_File: binlog57.000007
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 1723
Relay_Log_Space: 1937
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3302
Master_UUID: 5cee6f9f-5ab8-11e6-a081-000c29d4dc3f
Master_Info_File: /home/mysql/I3303/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:17-21
Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-21
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec) [zejin] 3303>select * from t_users;
+----+------+
| id | name |
+----+------+
| 1 | chen |
| 2 | ok |
| 3 | li |
+----+------+
3 rows in set (0.00 sec) 数据也已经完全与主的一致了,复制正常后再change到3301master上。
[zejin] 3303>change master to master_host='192.168.1.240',master_port=3301,master_user='repl',master_password='',master_auto_position=1;
Query OK, 0 rows affected, 2 warnings (0.01 sec) [zejin] 3303>start slave;
Query OK, 0 rows affected (0.00 sec)
上面这种情况是基于还有另一个从库已经接收到了master的所有binlog的情况下,那如果结果只是M-S,也发生了如上的问题,那又该如何恢复,我们有如下两种方法:
 
目前Master上状态为:
[zejin] 3301>show global variables like '%gtid%';
+----------------------------------+-------------------------------------------+
| Variable_name | Value |
+----------------------------------+-------------------------------------------+ | gtid_executed | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-27 |
……
| gtid_purged | a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-25 |
……
+----------------------------------+-------------------------------------------+
8 rows in set (0.00 sec)
 
Slave上状态为:
[zejin] 3303>show slave status \G
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.1.240
Master_User: repl
Master_Port: 3301
Connect_Retry: 60
Master_Log_File: binlog57.000016
Read_Master_Log_Pos: 729
Relay_Log_File: zejin240-relay-bin.000003
Relay_Log_Pos: 4
Relay_Master_Log_File: binlog57.000016
Slave_IO_Running: No
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 729
Relay_Log_Space: 194
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 1236
Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.'
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3301
Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f
Master_Info_File: /home/mysql/I3303/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp: 160809 17:54:42
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:22
Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-22
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)

和之前同样类型的错误,我们恢复的思路为:

把slave上的gtid_purged设置为master还没有被purge掉的值,最后借助第三方一致性同步工具来做数据的一致性同步。
 
我们需要先在slave上做一下reset master来清除gtid的一些信息,直接设置会报如下错误:
[zejin] 3303>set global GTID_PURGED="a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-26";
ERROR 1840 (HY000): @@GLOBAL.GTID_PURGED can only be set when @@GLOBAL.GTID_EXECUTED is empty.

正确操作步骤如下(在slave上执行):

[zejin] 3303>reset master;
Query OK, 0 rows affected (0.02 sec) [zejin] 3303>set global GTID_PURGED="a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-26";
Query OK, 0 rows affected (0.00 sec) [zejin] 3303>start slave;
Query OK, 0 rows affected (0.00 sec) [zejin] 3303>show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.1.240
Master_User: repl
Master_Port: 3301
Connect_Retry: 60
Master_Log_File: binlog57.000018
Read_Master_Log_Pos: 728
Relay_Log_File: zejin240-relay-bin.000004
Relay_Log_Pos: 718
Relay_Master_Log_File: binlog57.000018
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 728
Relay_Log_Space: 968
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3301
Master_UUID: a97983fc-5a29-11e6-9d28-000c29d4dc3f
Master_Info_File: /home/mysql/I3303/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:22:27
Executed_Gtid_Set: a97983fc-5a29-11e6-9d28-000c29d4dc3f:1-27
Auto_Position: 1
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
当然执行完这个之后数据是不一致的,那么此时就可以通过pt-table-checksum和pt-table-sync来做数据的一致性恢复了。
 
 
我们还有另一种方法,那就是重建slave,方法如本文最开始的那样新建一个slave,但是在由于目前slave上已经有gtid的一些信息,所以在恢复时得先在slave上reset master,具体操作如下:
在slave上操作:

reset master
source dump3301.sql;
change master to master_host='192.168.1.240',master_port=3301,master_user='repl',master_password='',master_auto_position=1;
start slave;
show slave status\G

至此完成slave同步异常的恢复。

 
 
 
 
 
 
 
 
 

MySQL5.7(5.6)GTID环境下恢复从库思(qi)路(yin)方(ji)法(qiao)的更多相关文章

  1. MySQL5.7(5.6)GTID环境下恢复从库思路方法(转发)

    要讨论如何恢复从库,我们得先来了解如下一些概念: GTID_EXECUTED:它是一组包含已经记录在二进制日志文件中的事务集合 GTID_PURGED:它是一组包含已经从二进制日志删除掉的事务集合. ...

  2. mysql 在gtid环境下缺少一部分binlog部署从库

    我的环境: 有两台linux服务器 一台是192.168.1.1  mysql  端口3301 一台是192.168.1.2   mysql 端口3303 要讨论如何恢复从库,我们得先来了解如下一些概 ...

  3. gtid环境下mysqldump对于set-gtid-purged的取值

    gtid环境备份的时候,还在为set-gtid-purged=0|1的选择而烦恼吗,一起来分析一下. [mysql@lxd-vm1@/home/mysql]$ mysqldump --help | g ...

  4. window环境下 恢复odoo数据库备份文件时产生的 Database restore error: Command `psql` not found.

    1,首先先查看 PostgreSQL 是否安装在C盘,如果安装在其他盘 则需要配置环境变量 配置完成后重启服务就可以了 2, 如果还不行,只需在odoo.conf中添加一个配置设置.也就是在odoo项 ...

  5. Windows环境下编译Assimp库生成Android可用的.so或.a文件

    在做项目过程中需要使用Assimp这个3D模型读取库来读取obj格式的模型,因为项目是基于Android平台,采用NDK开发,所以就打算编译Assimp库并生成.so文件.本文使用Assimp-v.5 ...

  6. C#环境下的数值计算库:MathNet

    下面用一个简单的例子来说明MathNet的使用方法: 1. 进入MathNet官网找到数值计算库Math.NET Iridium(Numerics)并下载: 2. 将下载的文件解压缩,在目录下的Bin ...

  7. Windows10系统python环境下安装Dlib库(转载,蔡军帅亲测可用)

    Dlib是一个很优秀的机器学习库,最近做人脸识别要用到这个库,简要记录一下配置过程,准备工作: 1.python环境 2.安装好pip(这里有个简单的安装教程) 3.Dlib包,贴一个我安装的版本,链 ...

  8. Mac环境下安装python库时出现ModuleNotFoundError: No module named 'XXX'

    在使用pip3安装爬虫的一些有关库时发现安装成功后,import时发现又找不到,后来发现一个解决方法. 在Anaconda-Navigator里面打开environment里面寻找发现真的没有,这时再 ...

  9. Liunx环境下配置matplotlib库使用中文绘图

    最近在使用matplotlib库的过程中需要用到中文绘图,在网上找了好多种方法,最终用一种方法解决了,在此记录. 首先Linux是有自己的中文字体的,叫做"Droid Sans Fallba ...

随机推荐

  1. Redhat Linux /etc/profile 与 /etc/bashrc 的区别

    最近学习RHCE,在umask这里,书里说要修改/etc/profile和/etc/bashrc两个文件,却没有说明这两个区别.于是在上网查看之后倒是明白了各是怎么用的./etc/profile是对应 ...

  2. [.NET领域驱动设计实战系列]专题十一:.NET 领域驱动设计实战系列总结

    一.引用 其实在去年本人已经看过很多关于领域驱动设计的书籍了,包括Microsoft .NET企业级应用框架设计.领域驱动设计C# 2008实现.领域驱动设计:软件核心复杂性应对之道.实现领域驱动设计 ...

  3. 依赖注入的威力,.NET Core的魅力:解决MVC视图中的中文被html编码的问题

    有园友在博问中提了这样一个问题 —— .NET Core 中文等非英文文字html编码输出问题,到我们的 ASP.NET Core 项目中一看,也是同样的问题. 比如下面的Razor视图代码: @{ ...

  4. winform 通过webservice向服务器提交图片需要注意的地方

    最近一个winform项目中需要通过拍照或者上传本地文件或者截图的方式把产品图片上传到服务器,最后选择了服务器部署webservice的方式来进行.其中遇到了一些问题记录下来. 不多说,直接上服务端代 ...

  5. <HTML5和CSS3响应式WEB设计指南>译者序

    "不是我不明白,这世界变化快."崔健的这首歌使用在互联网领域最合适不过.只短短数年的功夫,互联网的浪潮还没过去,移动互联网的时代已经来临.人们已经习惯将越来越多的时间花在各种移动设 ...

  6. Mybatis错误(一)org.apache.ibatis.exceptions.PersistenceException

    在映射文件中,通过parameterType指定输入参数的类型,类型可以是简单类型.hashmap.pojo的包装类型.在测试包装类型过程中产生了一个错误:org.apache.ibatis.exce ...

  7. 启发式算法(Heuristic Algorithm)

    背景: 李航的<统计学习方法>一书中提到:决策树算法通常采用启发式算法,故了解之 问题解答: 时间有限,这里也只是将算法和启发式算法的区别和简单发展摘录如下: 一.算法和启发式方法之间的差 ...

  8. 创建Cookie,简单模拟登录,记录登录名,购物车记录先前添加内容,session控制登录

     工作任务:模拟淘宝登录和购物车功能:使用cookie记录登录名,下次登录时能够记得上次的登录名,使用cookie模拟购物车功能,使用session记住登录信息并验证是否登录,防止利用url打开网站, ...

  9. fir.im Weekly - 论个人技术影响力是如何炼成的

    每个圈子都有一群能力强且懂得经营自己的人,技术圈也是如此.本期 fir.im Weekly 一如往期精选了一些实用的 iOS,Android 开发工具和源码分享,还有一些关于程序员的成长 Tips 和 ...

  10. angular测试-Karma + Jasmine配置

    首先讲一下大致的流程: 需要node环境,首先先要安装node,node不会?请自行搜索.版本>0.8 安装node完成之后先要测试下npm是否测试通过,如下图所示 首先看下目录结构 目录为:F ...