database - When to close db connection on android? Every time after your operation finished or after your app exit

Question

I have an android application that access local sqlite3 db frequently, for performance consideration so i always keep the connection open. But one of my friends recommended me to open/close the connection every operation.

1) What's your guys opinion on these two methods ? cons/pros. 2) I did some testing and find the DB connection doesn't have too much perf overhead. Does the performance overhead of DB connection varies on the size of the DB ?

Answer 1

I don't know of any performance penalties in frequent closing/opening of the database (regardless of its size). I think the answer to this question also depends on what type of application is accessing the database.

Do you "re-query" the database a lot?
Then it seems rectified to keep it open.

Do you fetch different data each time you fetch something?
Again, it seems reasonable to leave it open (as you won't gain in caching the data instead).

Are there any other applications accessing the same database?
If there is a risk for concurrency or blocking issues, it might be wise to close the database after finished reading/writing from/to it.

Generally I would say that you might gain more in caching data than in leaving the database open (contra closing it) when optimizing for performance.