有一个项目上的数据库使用了几个月.mdf文件与.ldf文件加起来竟然达到了100G+,这样下去硬盘会被撑爆的。 这样的原因是因为异常情况造成某个数据表中有大量的冗余数据,将异常数据表的冗余数据清理之后,mdf文件并没有变小,因为对数据库进行了删除操作,ldf
有一个项目上的数据库使用了几个月.mdf文件与.ldf文件加起来竟然达到了100G+,这样下去硬盘会被撑爆的。
这样的原因是因为异常情况造成某个数据表中有大量的冗余数据,将异常数据表的冗余数据清理之后,mdf文件并没有变小,因为对数据库进行了删除操作,,ldf文件反而变增大很多!根据项目情况考虑使用作业方式定时压缩数据文件大小,压缩之后只有十几兆的大小。
Setp1:开启SQL Server Agent服务
使用作业需要SQL Agent服务的支持,并且需要设置为自动启动,否则你的作业不会被执行。
以下步骤开启服务:开始——>运行——>输入"services.msc"——>进入服务,开启SQL Server Agent服务,并设置为自动。
如图:
Setp2:创建作业
创建作业的过程这里就不说了,作业执行的命令为:
(size(, ) AvailableSpaceInMB ) () HCJK_Customer RECOVERY SIMPLE; SHRINKFILE (HCJK_Customer, SHRINKFILE (HCJK_Customer_log, HCJK_Customer --BEGIN -- PRINT @Error --END

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The working principle of MySQL query cache is to store the results of SELECT query, and when the same query is executed again, the cached results are directly returned. 1) Query cache improves database reading performance and finds cached results through hash values. 2) Simple configuration, set query_cache_type and query_cache_size in MySQL configuration file. 3) Use the SQL_NO_CACHE keyword to disable the cache of specific queries. 4) In high-frequency update environments, query cache may cause performance bottlenecks and needs to be optimized for use through monitoring and adjustment of parameters.

The reasons why MySQL is widely used in various projects include: 1. High performance and scalability, supporting multiple storage engines; 2. Easy to use and maintain, simple configuration and rich tools; 3. Rich ecosystem, attracting a large number of community and third-party tool support; 4. Cross-platform support, suitable for multiple operating systems.

The steps for upgrading MySQL database include: 1. Backup the database, 2. Stop the current MySQL service, 3. Install the new version of MySQL, 4. Start the new version of MySQL service, 5. Recover the database. Compatibility issues are required during the upgrade process, and advanced tools such as PerconaToolkit can be used for testing and optimization.

MySQL backup policies include logical backup, physical backup, incremental backup, replication-based backup, and cloud backup. 1. Logical backup uses mysqldump to export database structure and data, which is suitable for small databases and version migrations. 2. Physical backups are fast and comprehensive by copying data files, but require database consistency. 3. Incremental backup uses binary logging to record changes, which is suitable for large databases. 4. Replication-based backup reduces the impact on the production system by backing up from the server. 5. Cloud backups such as AmazonRDS provide automation solutions, but costs and control need to be considered. When selecting a policy, database size, downtime tolerance, recovery time, and recovery point goals should be considered.

MySQLclusteringenhancesdatabaserobustnessandscalabilitybydistributingdataacrossmultiplenodes.ItusestheNDBenginefordatareplicationandfaulttolerance,ensuringhighavailability.Setupinvolvesconfiguringmanagement,data,andSQLnodes,withcarefulmonitoringandpe

Optimizing database schema design in MySQL can improve performance through the following steps: 1. Index optimization: Create indexes on common query columns, balancing the overhead of query and inserting updates. 2. Table structure optimization: Reduce data redundancy through normalization or anti-normalization and improve access efficiency. 3. Data type selection: Use appropriate data types, such as INT instead of VARCHAR, to reduce storage space. 4. Partitioning and sub-table: For large data volumes, use partitioning and sub-table to disperse data to improve query and maintenance efficiency.

TooptimizeMySQLperformance,followthesesteps:1)Implementproperindexingtospeedupqueries,2)UseEXPLAINtoanalyzeandoptimizequeryperformance,3)Adjustserverconfigurationsettingslikeinnodb_buffer_pool_sizeandmax_connections,4)Usepartitioningforlargetablestoi


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