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Recently, we encountered a very difficult problem. The monitoring system DPA found that a custom scalar function was invoked very frequently, which was beyond the scope of spectrum. Then when Troubleshooting is a problem, I do encounter some problems that make me very confused. Here is a little thought and try to solve the problem. If you have ...

Deep Understanding of MyBatis (III) - MyBatis Update Operational Execution Process MyBatis is initialized by parsing the configuration file and generating the Configuration object. After initialization, SqlSession Factory can be obtained for dynamic operation. The insert operation, delete operation and update operation in MyBatis are ...

Modify the port SCAN listens on Modify the port SCAN listens on to 3521, and the port local listens on remains the same, at 1521: [root@web1 ~]# srvctl modify scan_listener -p 3521 1 View the listening status after modification: [grid@web2 ~]$ lsnrctl status LISTENER_SCAN1 LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 06-May-2 ...

Note: This article is reproduced from Nan Ke Meng Recently, I have been too busy to update my blog. Today, I am busy to continue my Mybatis study tour. In the first nine chapters, the configuration and use of mybatis are introduced. Then this chapter will go into the source code of mybatis and analyze the execution process of mybatis. SqlSessio ...

Note: This article is reproduced from Nan Ke Meng In the last article, "Deep and Simple Mybatis Series (4) - - Configuration Detailed Type Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Aliases Alias (Mybatis Source Chapter)" introduced the use of aliases in mybatis and ...

Now let's talk about the meaning of each parameter in the oracle execution plan Let's illustrate with an example below To add this, there are several types of trace s Sequence Number command explain 1 SET AUTOTRACE OFF This is the default value, which turns off Autotrace 2 SET AUTOTRACE ON EXPLAIN Show only execution plans 3 ...

MySQL Create Data Table Creating a MySQL data table requires the following information: Table Name Table field name Define each table field grammar The following is the general SQL syntax for creating MySQL data tables: CREATE TABLE table_name (column_name column_type); In the following example, we will create the data table runoob_tb ...

MySQL UPDATE Query If we need to modify or update the data in MySQL, we can use the SQL UPDATE command to operate. . grammar Following is the UPDATE command to modify the general SQL syntax for MySQL table data: UPDATE table_name SET field1=new-value1, field2=new-value2 [WHERE Clause] You can update one or more fields at the same time. Yo ...

1. Introduction to databases What is a database?(https://www.cnblogs.com/alex3714/articles/5950372.html) A Database is a warehouse that organizes, stores, and manages data according to its structure.Each database has one or more different API s for creating, accessing, managing, searching, and replicating stored data.We can also store data in f ...

One-to-one Joint Key Linkages in Hibernate Learning Notes 7 We explained one-to-one foreign key Association and one-to-one primary key Association earlier. This blog article introduces joint primary key association. First of all, review the main keys, you can refer to the previous blog article: http://blog.csdn.net/u010412719/article/de ...