Course Intermediate  11369

Course Introduction："Self-study IT Network Linux Load Balancing Video Tutorial" mainly implements Linux load balancing by performing script operations on web, lvs and Linux under nagin.

Course Advanced  17683

Course Introduction："Shangxuetang MySQL Video Tutorial" introduces you to the process from installing to using the MySQL database, and introduces the specific operations of each link in detail.

Course Advanced  11384

Course Introduction："Brothers Band Front-end Example Display Video Tutorial" introduces examples of HTML5 and CSS3 technologies to everyone, so that everyone can become more proficient in using HTML5 and CSS3.

Course Introduction：Redis provides commands for clearing cached data, including: deleting a single key: DEL, UNLINK clearing the entire database: FLUSHDB, FLUSHALL

2024-04-19 comment 0  1228

Course Introduction：The PHP file cache class extracted from the CI community's stblog and CI's file_helper class is a simple file-based key->value cache class. This class can be used to cache some basic information, such as some infrequent changes in the header, footer, and sidebar of the blog, and the content taken out from the database. Before fetching the data, first determine whether the content in the file cache has expired. If it has not expired, take it out. , if it expires, connect to the database to query, rewrite the results into the file cache, and update the expiration time.

2018-05-26 comment 0  2138

Course Introduction：How to clear the cache in MySQL requires specific code examples. Caching is one of the important performance optimization technologies in the MySQL database. MySQL uses cache to store frequently queried data and query results to improve the reading speed of the database. However, in some cases, query results may be inaccurate or outdated due to the presence of cache. To solve this problem, we can manually clear the MySQL cache. MySQL's cache is generally divided into two types: query cache and InnoDB cache. The following describes how to clear

2024-02-19 comment 0  824

Course Introduction：Why is the cache deleted instead of updated? If it is an update, there is a distributed transaction problem, the cache may be modified, and the database modification may fail. If you just delete the cache, even if the database modification fails, the next query will directly fetch the data from the database, and no dirty data will appear. What is delayed double deletion? That is, when adding, deleting or modifying an entity class, the cache of the entity class must be cleared. The clearing position is before and after the database operation method. Using the method of proof by contradiction, only deleting the conclusion first and then deleting it later leads to the conclusion that both deletion before and after deletion are problematic. Therefore, the strategy of delayed double deletion is adopted. Thinking 2: Why is delay still a proof by contradiction? The situation in the figure below shows the situation where the old cache still exists after double deletion. The delay is to ensure that the change cache operations of other transactions have been completed before modifying the database -> clearing the cache.

2023-05-26 comment 0  3182

Course Introduction：The class library itself contains many classes that have state dependencies. Such as FutureTask, BlockingQueue, etc. Some operations in these classes are based on state preconditions. For example, you cannot delete elements from an empty queue or obtain the calculation result of an unfinished task. Between these two operations...

2018-07-19 comment 0  2653