How to restart MySQL in linux

Don't panic when encountering the MySQL data sheet corruption. You can troubleshoot problems through CHECKTABLE. When the server crashes, the disk is full or the query error occurs after abnormal shutdown, the result is stuck, the results are inconsistent, or the report is damaged during startup, the CHECKTABLEyour_table_name should be used to check the table status. If Msg_text is OK in the output, there is no problem, and if Corrupt or Founddeletedrow is prompted, there is an error. After discovering problems, you should first back up the data and confirm the storage engine type. MyISAM can be repaired using REPAIRTABLE. InnoDB recommends using mysqldump to export and rebuild or enable innodb_force_rec.

DataanonymizationinMySQLisachievedthroughSQLqueries,built-infunctions,maskingtechniques,andautomationtools.1)DirectSQLquerieslikeUPDATEstatementscanreplacesensitivefieldswithfakedata.2)Built-infunctionssuchasSHA2(),MD5(),andRAND()helpscrambledataeffe

MySQL performance tuning needs to start from configuration, SQL, structure and operation and maintenance. 1. Reasonably configure server parameters, such as setting innodb_buffer_pool_size to 50%~80% of physical memory, adjust max_connections to avoid resource contention, and turn off query cache before MySQL8.0; 2. Optimize slow queries, enable slow query logs and use EXPLAIN to analyze execution plans, reduce full table scanning; 3. Reasonably design database structure and indexes, establish effective joint indexes, and clean redundant indexes regularly; 4. Continuous monitoring and maintenance, use tools to monitor performance indicators, regularly execute ANALYZETABLE and OPTIMIZETABLE, and reasonably arrange backups to

MySQL does not support cross-schema foreign key constraints, but can be implemented in workarounds such as using triggers to simulate constraints, application-layer control consistency, merging schemas or symlinking, and managing data operations through stored procedures. 1. The trigger can check whether the reference exists before inserting or updating, ensuring consistency but requires manual maintenance; 2. The application layer controls to check whether the data exists first when inserting or deleting, which is suitable for ORM and microservice architectures but increases application complexity; 3. Merging schema or using view/symbol links can indirectly implement foreign key references, but maintenance costs and compatibility restrictions; 4. Stored procedures centrally process data operations, unify logical control and ensure consistency, but all data access must be encapsulated. When choosing a plan, you should combine it

TooptimizeMySQLforReal-timeBidding(RTB)platforms,useInnoDBasthestorageenginewithinnodb_file_per_tableenabledandinnodb_buffer_pool_sizesetto60–80%ofavailableRAM.AvoidMyISAMduetoitstable-levellocking.OptimizequeriesbyavoidingSELECT*,usingcoveringindexe

Using MySQL stored procedures and functions can improve the logical organization and maintainability of modern web applications. 1. Reduce the use of complex SQL in application code by encapsulating reuse logic, such as calculating user activity scores or formatting order summary; 2. Improve performance, reduce round-trip communication between the database and the application through a single call; 3. Process business rules near the data layer, such as checking inventory before inserting an order to ensure consistency across applications; 4. Enhance security, and limit direct table access by granting only execution permissions to prevent misuse or malicious operations. The rational use of these features simplifies development and improves system integrity.

To handle complex recursive queries in MySQL, recursive CTE should be used; 1. They process hierarchical data by repeatedly executing subqueries, which is suitable for scenarios such as organizational structures; 2. When using it, you must first define the anchor members, and then connect the recursive part through UNIONALL; 3. Pay attention to avoiding infinite loops and controlling the recursive depth; 4. Recursive CTE can also be used to generate date ranges and parse nested JSON and other non-hierarchical structure scenarios; 5. In terms of performance, you should pay attention to filtering timing, reduce the number of iterations, and consider switching to application layers or graph databases when the amount of large data is large.

The configuration steps of MySQL master-slave replication include: 1. Preparation work to ensure that the master-slave server environment is consistent and create a dedicated replication account; 2. Configure the master library, enable binary logs and export data; 3. Configure the slave library, import data and start the replication process; 4. Pay attention to common problems and precautions, such as network latency, read-only mode, and failover schemes. First, you need to create an account with REPLICATIONSLAVE permission in the main library and ensure that the communication between the master and slave is normal; then the main library opens the binary log and records the log location information, and exports the data through mysqldump; then sets an independent server-id from the slave library, imports the data using the CHANGEMASTER command to connect to the main library and starts the copy thread;