sqlite缓存查询的结果以进行优化吗? [英] is sqlite caching the results of the query for optimization?

问题描述

我注意到sqlite中的这种行为.当我重新使用游标对象时，任务管理器中的工作集内存会不断增加，直到我的程序抛出内存不足异常为止.

I've noticed this behavior in sqlite. When I re-use the cursor object, the working set memory in the task manager keeps increasing until my program throws a out of memory exception.

我重构了代码，以便每次查询时都打开与sqlite文件的连接，查询我想要的内容，然后关闭该连接.

I refactored the code such that each time I query I open a connection to the sqlite file query what I want and then close the connection.

后者似乎不那么耗费内存.它不会增加超过特定的点.

The latter somehow seems to be not so memory-hungry. It doesn't increase beyond a certain point.

我对sqlite数据库所做的只是针对一个表的简单选择(包含两个聚合).

All I do with my sqlite db is simple select (which contains two aggregations) against a table.

这是我们可以控制的行为吗?我想重用我的游标对象，但又不想耗尽内存...

Is this a behavior we can somehow control? I'd want to reuse my cursor object, but not want memory to be eaten up...

推荐答案

请参见 SQLite:PRAGMA cache_size

默认情况下，缓存大小相当大(〜2MB)，即每个连接一次.您可以使用SQL语句将其设置为较小:

By default the cache size is fairly big (~2MB) and that is per-connection. You can set it smaller with the SQL statement:

PRAGMA cache_size=-KB

使用负的-" KB值将其设置为千字节大小，否则设置要使用的页面数.

Use the negative '-' KB value to set it as a size in KiloBytes, otherwise it set the number of pages to use.

此外，如果使用多个连接，则可能要使用共享缓存来节省内存: SQLITE:共享缓存

Also, if using multiple connections you might want to employ a shared cache to save memory: SQLITE: Shared Cache

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