Programmer Think

introduction Recently, the little ape needs to be on the project according to the requirements of the leaders. The database needs to realize master-slave replication. The necessity and principle of master-slave replication of the database are not explained too much in this paper. Interested children's shoes can refer to some articles on the In ...

catalogue 1, String data type 2, List data type 3, Hash data type (hash type) 4, Set data type (unordered set) 5, Sorted Set data type (zset, ordered set) 1, String data type Overview: string is the most basic type of redis, which can store up to 512MB of data. String type is binary safe, that is, it can store any data, such as numbers, ...

Before that, we learned the global configuration file of mybatis. Now we begin to learn the mapping file of mybatis. In the mapping file, you can write the following top-level element labels: cache – Cache configuration for this namespace. cache-ref – Cache configuration that references other namespaces. resultMap – Describing how to load obje ...

This case comes from a production failure of a two node rac of a customer. The phenomenon is that a large area of gc buffer busy acquire leads to business paralysis.First, check the AWR header information and load profile of node 1:1 node AWRKey information points obtained:For LCPU 256 system, AAS=13379.42/59.91=223, indicating that the system ...

Master-slave database theoretical knowledge First step The master's operations on the data are recorded in the Binary log. Before each transaction updates the data, the master records these changes and writes them to the Binary log serially. After completing the log writing, the master notifies the storage engine to commit the transaction. T ...

In the development process, it is sometimes encountered that only a part of a certain field of the database is required. Sometimes, this scenario is more convenient and faster to operate directly through the database than through code. MySQL has many string functions that can be used to deal with these requirements, such as left, right, subs ...

https://blog.csdn.net/m0_50546016/article/details/120070003 I ❤ Introduction to database and SQL ❤ Case insensitive 1. SQL classification SQL can be divided into two parts: data operation language (DML) and data definition language (DDL). ⭐ Data query language (DQL) ⭐ Data Manipulation Language (DML) Data definition language ...

1, What is JDBC Java database connectivity. Essence of JDBC: JDBC is a set of interface s formulated by SUN company. Interfaces have callers and implementers. Interface oriented calling and interface oriented writing implementation classes belong to interface oriented programming. Polymorphic mechanism is very typical: Abstract oriented program ...

Previous: I'm learning database at station b (VI): regular expressions in DQL 1, Multi table relation It can be summarized as: one to one, one to many / many to one relationship, many to many 1. One to one relationship Example: one ID card can only correspond to one person be careful: (1) Add a unique foreign key in any table to point to the ...

Database connection description When it comes to TCP keepalive related settings, you can't avoid the topic of database connection. At present, in most use environments, database connections are long connections, that is, connections can be reused. Because the database connection is different from HTTP connection, HTTP is stateless, and the co ...