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This article mainly gives you a brief description of what to do if the application cannot connect if you set the MySQL database parameters improperly. You can look up the relevant professional terms on the Internet or find some related books to supplement them. We will not dabble here, so let's go straight to the topic. I hope this article can bring some practical help to you how to set the MySQL database parameters improperly so that the application cannot connect.

1. Optimize the index of OA database

two。 Modify the minimum number of database connections from 30 to 5

3. Modify the MySQL database parameters to add transaction-isolation = Read Committed.

Because debugging is working time, the database and application are not restarted after the modification is completed. I rebooted on Saturday morning, but the reboot failed all the time, and the manufacturer's technology could not be contacted. We'll have to solve it on our own.

Looking back at several of his amendments, Article 1 and 2 will not cause the application to fail to start, it seems that there is only Article 3. Check the startup log of Tomcat and find that the database is not connected, but the database is started normally, but why can't you connect?

Comment out the added parameters, restart the database, and then start the application. Why is that?

It suddenly occurred to me that I started the log mode of the database in order to replicate from the master, so could it be the conflict between the two? After a search, you can see some relationship between the format of the log mode and the previous transaction:

The log mode defaults to STATEMENT, while my database uses the default at the time, which seems to be a conflict between the log mode and the transaction level. Modify the database configuration file again and modify the log mode:

Binlog_format=MIXED

Transaction-isolation = Read Committed

Restart the database, and then start the application, there is no problem.

If you can't connect to the application due to improper setting of MySQL database parameters, let's stop here. If you want to know about other related issues, you can continue to pay attention to our industry information. Our section will capture some industry news and professional knowledge to share with you every day.

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