On 21 Dec 2017, at 4:34pm, curmudgeon <tam118...@hotmail.com> wrote: > Put it this way, if I create n temp tables will there be n_+ 1 page caches > or just the main cache containing a further n temporary caches?
Try it and see. But unless you intentionally make us strange numbers the problem you’ll run into is not set by SQLite, it’s down to the amount of memory your OS is allowing your application to use. The SQLite settings you use are unlikely to have any effect on what actually happens. This is one of the reasons I think you’re wasting your time worrying about this stuff. > I would've liked to have known if sqlite took care of it > all for me or if it was down to the OS. SQLite has no low-level access to your computer memory. If the documentation says it is keeping some data in memory, it means that SQLite allocates that memory by asking your OS for it, just the same as if you’d done it yourself in C. And your OS will manage that memory using virtual memory the same as it would for any other memory your application uses. If the operating system doesn’t use virtual memory then you’ll get an "out of memory" error. > All I was able to determine was that setting temp_store = 2 (MEMORY) did > speed up the queries but I've no idea if using that setting is risky on a > lower spec pc. SQLite can’t do anything with its memory that the rest of your program can't do. So if you allocate too much your OS will step in and handle things for you, outside of SQLite’s control. Also you should be aware that virtual memory is a very efficient way of letting your computer handle RAM and disk. By artificially allocating RAM to specific resources you are preventing the OS using that RAM in what /it/ thinks is the most efficient way. And generally computers are better at this stuff than humans are. Lastly, don’t confuse your development environment with your runtime environment. The amounts of memory you have free, and the memory your application will be allowed to use when it’s in real life use may be totally unlike what’s available in your IDE on your dev computer. So don’t bother picking numbers for making things run really fast on your development platform. The recommendation in this case is to leave the configuration to its default settings, leave the journal_mode at its default setting, and just go ahead and write your software the way your programming language and SQL suggest to you. Rely on the OS and SQLite to manage memory properly, which is usually very well. Once you have a ton of experience about how your program runs in real life, /then/ you can start thinking about optimization. Simon. _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
