title: When should I call close() on SQLiteOpenHelper used by ContentProvider
body: <p>In my android app, I use SQLiteOpenHelper to implements ContentProvider.
  Query, add, delete operations are all through ContentProvider.</p>
  
  <p>But in one of my android phone(htc g13), I found *.db-wal file in directory /data/data/[package name]/databases. And the file size increate very fast when operating with ContentProvider. It occupied user RAM space too much.</p>
  
  <p>It is recommended to close the SQLiteOpenHelper to solve my problem (it is useful) in post <a href="https://stackoverflow.com/questions/6115279/android-database-size-wont-decrease-on-htc-thunderbolt">enter link description here</a>. </p>
  
  <p>But I want to find a "place" to add the "close()" method since I am not using SQLiteOpenHelper directly (using through ContentProvider). query() method in ContentProvider must return a Cursor, and SQLiteDatabse should stay in open state. </p>
  
  <p>I'm confused, what show I do now to keep *.db-wal gone and use ContentProvider normally?</p>