Transactions in GreenDao

问题

I'm using GreenDao to store a lot of data, coming from a REST service.

A lot of my entities are connected with relations. Everything works great, but tomorrow I have to implement a rocksolid workflow.

When I load my data I have to check if an error occurs. If so, I have to make sure nothing is stored in the SQLite DB.

Normally I would work with transactions and rollback in case of an exception, otherwise commit to the db.

For now I just use insertordelete to save an entity, everytime I created an object.

What would be the way to implement this?

回答1:

On inserts and updates Greendao checks if there is a ongoing transaction. If that is the case greendao will not start a new transaction.

So the only thing to do is to start a transaction on your database and commit/rollback after your work is done or you notice an error. All inserts and updates will be in the same transaction which has benefits concerning data consistency and also on performance, since greendao will start new transactions with commit/rollback for every insert and update operation.

Summarized you can use code like this:

SQLiteDatabase db = dao.getDatabase();
db.beginTransaction();

try {
    // do all your inserts and so on here.
    db.setTransactionSuccessful();
} catch (Exception ex) {
} finally {
    db.endTransaction();
}

I also tweaked my greendao a bit so that it doesn't cache inserted objects to get further performance and memoryusage benefits (since I insert a lot of data once and I only use very few data during runtime depending on user input). See this post.

来源：https://stackoverflow.com/questions/25189764/transactions-in-greendao