方法1:将php.ini中的session.gc_maxlifetime设置为9999,重启apache 方法2: test 方法3: test 如何取得一个网页或文件的内容 方法1:(对于php5及更高版本) test 方法2: test 如何取得一个网页或文件的内容 方法1:(对于php5及更高版本) test 方法2: test mysql中explain后的结果都代表什么? 通过explain,可以...
2.5.derived:派生表,在 FROM 子句的查询语句,表示从外部数据源中推导出来的,而不是从 SELECT 语句中的其他列中选择出来的。 set session optimizer_switch='derived_merge=off'; #关闭MySQL5.7对衍生表合并优化 explain select * from (select user_id from orders where id = 1) as temp; set session optimi...
前言 索引类似大学图书馆建书目索引,可以提高数据检索的效率,降低数据库的 IO 成本。MySQL在 300w 条记录左右性能开始逐渐下降,虽然官方文档说 500~800w 记录,所以大数据量建立索引是非常有必要的。MySQL 提供了 EXPLAIN,用于显示 SQL 执行的详细信息,可以进行索引的优化。使用 EXPLAIN 关键字可以模拟优化器执行 SQL ...
system是const的特例,表里只有一条数据匹配时为 system; (使用主键或者唯一索引的时候会出现) mysql> set session optimizer_switch='derived_merge=off'; #关闭mysql5.7新特性对衍生表的合并优化 mysql>explain extended select * from (select * from film where id = 1) tmp;mysql> set session optimizer_swit...
Hi there. I am a complete newbie with php and vscode and xdebug. I put in my localSourceRoot and ServerRoot but the Intellisense tells me that it is deprecated and to use pathMappings instead. I have no idea what information to put in th...
Description:Technically, this is a duplicate of the closed reporthttps://bugs.mysql.com/bug.php?id=95850, however, I think that something's still wrong. Specifically, the guide (https://dev.mysql.com/doc/refman/8.0/en/explain-for-connection.html) states: > If you have the PROCESS privile...
--- TRANSACTIONS --- Trx id counter 163215 Purge done for trx's n:o < 163214 undo n:o < 0 state: running but idle History list length 72 LIST OF TRANSACTIONS FOR EACH SESSION: ---TRANSACTION 163206, not started MySQL thread id 4, OS thread handle 0xac0, query id 86 localhost 127...
1 使用方式 set session optimizer_trace= “enabled=on”; 然后执行你要分析的SQL, 再执行SELECT trace FROM information_schema.OPTIMIZER_TRACE;就可查看SQL的Optimizer Trace信息 DEMO: set session optimizer_trace= “enabled=on”; selectfrom actor ; ...
select * from v$session where type ='BACKGROUND'; Here are some of the most important Oracle background processes: ARCH (Optional) Archive process writes filled redo logs to the archive log location(s). In RAC, the various ARCH processes can be utilized to ensure that copies of the ar...
ConvertFrom-SecureString fails in remote powershell session even though WSManCredSSP is configured for both client and server. Converting "whencreated" (System.DirectoryServices.ResultPropertyValueCollection) to string converting a string to [GUID] Converting a String value to Int64 Converting an old Bat...