WIP comment

SignalMessaging/utils/OWSDatabaseConverter.m

@@ -279,6 +279,17 @@ const NSUInteger kSQLCipherSaltLength = 16;
             return error;
         }
 
+
+        // MJK TODO: If possible, I think we want to avoid setting the default plain text header size.
+        //
+        // Ultimately it sets a static variable in the SQLCipher framework which will affect subsequent
+        // setups of SQLCipher DB's. In particular, unless we're careful to clean up after ourselves, this
+        // piece of global state will cause some tests to fail depending on the order in which they're called.
+        // Similarly, this global state could be a liability when trying to reason about our migration process.
+        // if the code that sets this global default ends up getting called earlier than we intend.
+        //
+        // IMO it's better to explicitly set the plaintext_header_size each time we open the db (which entails
+        // setting up the YapDatabase instance and for each newConnection.)
         NSString *setDefaultPlainTextHeaderPragma =
         [NSString stringWithFormat:@"PRAGMA cipher_default_plaintext_header_size = %zd;", kSqliteHeaderLength];
         error = [self executeSql:setDefaultPlainTextHeaderPragma