Dameng database_ Small matters needing attention during use

         It summarizes some mistakes in the process of use 、 Something to watch out for .

1、 Unexpected primary / standby asynchronous problem

         Friends do data development , On my recommendation , Try the database of Dameng as a routine exercise 、 Library of learning . According to the official documents, he built a data guard primary and standby cluster for trial .

         In a few days , Suddenly came to me and said , The database has bug, The primary and standby database data cannot be synchronized . I heard it very strange , After all, the data guard primary and standby cluster of Damon is a relatively mature product , There should be no such problem , I think it may be because he built it , There is a problem with the configuration .

         But I asked him for several main configuration files , I looked carefully for a long time , I didn't find any problems . I even began to suspect that it was his environmental problems . Hold that thought , I remotely connected to his machine , After the test , It is confirmed that there is no problem with the network communication between the primary and standby servers , I can't find out what the problem is . I connected to his cluster , After the test, it is found that there is no problem with the synchronization between the active and standby . I asked him about the scene of the problem , Try to reproduce .

         He said , Every time he inserted data into the test table , Connect to the standby database , No matter how long , No data can be queried , And what he configured is a backup database for real-time archiving , Logically speaking , It should be found out soon . The main and standby database clusters of Dameng , Give yourself internally MAL System to transmit Redo journal ,Redo What is stored in the log is the modified content of all physical data pages , The standby database receives the Redo After the log , Yes Redo Log replay , To synchronize data .

         I suddenly realized that some , I asked him ：“ After you operate the database , There is going on commit Submit ？” He froze for a moment , say ：“ No, ,commit What is it .” That's how I react , My friend is not old , Just graduated soon , What has been used before is MySQL、Hive、Spark Data development , It's not just Damon database , Even Oracle I've never been in contact with . Most of those databases are submitted automatically , By default, Dameng database is submitted manually , This led him to say that the primary and standby databases are not synchronized bug.

2、 Connection prompt network communication is abnormal

         This is what I encountered in the process of using , The problem of falling over several times .

         When connecting to the database instance , If you find out, you will report an error ： Abnormal network communication , There are generally two cases ：
The first is that the database instance service is not started , The resulting connection failed ;
The other is caused by port errors .

         Because Da Meng 8 The database is a single process 、 Multithreaded database , Therefore, each database instance is mainly distinguished by instance name and port number . Enter the wrong port number , It's like trying to open a wrong door with the right key .

3、 Graphical tool startup prompt permission is insufficient

         This is a recent problem . Under the graphical interface , Use the installation user to start tool Tools under the folder , Insufficient prompt authority , It was just opened a few days ago, and there is no problem .

         Explore why , It turned out to have been used root The user has opened relevant tools , If you want to solve this problem , Need to put tool The users and groups to which the folder belongs are changed to installation users .

         Of course , These are just a few of the problems I encountered , Share it here , It is to let more people know how to solve the corresponding problems . But there will always be problems that cannot be solved by individuals , So welcome to dream official community to discuss with you .

Dameng community address ：https://eco.dameng.com