Question

I m parsing JSON from a services, using ORMLite to persistent Object to the database as Iread out. 这些档案可能非常庞大,因此,我认为是在阅读时发射物体,而不是读数以百计的物体以备记忆和进行大规模攻击(这在讲智能的人中是稀有的)。然而,每个目标都将包含具有多种价值的收集(我试图为这些价值使用<代码>>ForeignCollection,因此每个数值都需作为单独目标处理),并且认为最好把所有物品一劳永逸地投在物体收集中,而不是在每一个人Sting或Integer上。

I believe that to make a group of commits in a batch, I would simply call dao.setAutoCommit(false), call dao.create() for each item, call dao.commit() afterwards and then call dao.setAutoCommit(true) to go back to piecemeal commits.

我有三个问题:

Is it right to commit as I go, or should I to a batch commit--even if it means up to a thousand objects would get committed at once?
Is it better to commit the collection of items one at a time, or in a batch?
Where do I get the databaseConnection value from that dao.setAutoCommit() and dao.commit() require? Maybe I missed it, but I can t find it in the documentation or examples.

Answer 1

是否有权在我到场时作出承诺,或者如果这意味着一度会发生多达1 000件物体的话,我是否应当承诺承诺。

If you have a large number of items it may be better commit a couple of 100 objects at once instead of 1000s. It depends a lot on the size of the objects so running it with various different batch sizes and timing them would be a good thing to try. As you mention, you need to balance memory and database performance. I d be curious of the results so please comment with your timing data.

是否最好在某个时间或批次中收集物品?

最好在批量中做事。我以前所努力的每一个数据库都是如此。

If you are talking about a foreign collection then there is really no difference between a foreign collection of objects and a large list of objects that you want to create. Both will benefit from batching.

我不会在每一物体创建后投入使用。我大打了100件外物体和它们拥有的任何外国物体。然后对100人做出修改,然后是100人。然后,将100至200条改为50条。你们应当看到偏袒点。

Did I answer this one right?

在什么地方,我从dao.setAutoCommit(和dao.commit()中获取数据库Connection值? 也许我错过了,但我可以在文件或实例中发现。

Edit #2:

正如@Chad所指出的,我错误地建议使用安的汽车。虽然Sqlite司机通常通过开始交易和在进行交易时承诺支持汽车开关。但安乐团似乎不支持这一点。在信安数据库链接中,该代码是一环。

在Anderson,与ORMLite共同开展批量任务的恰当方式是使用:dao.newBatchTasks(Callable)。类似:

accountDao.callBatchTasks(connectionSource,
  new Callable<Void>() {
    public Void call() throws SQLException {
        // insert a number of accounts at once
        for (Account account : accountsToInsert) {
           // update our account object
           accountDao.create(account);
        }
        return null;
    }
});

友情链接