objective-c - 巨大的核心数据对象

Question

我试图将 20 万条消息添加到核心数据对象，以证明 Twitter 应用程序的概念。这很好用，并且添加了我的实体。我有一个 UISearchBar 和一个 UITableView 来显示它们。然而，对于每一个新的 1000 个对象，我的时间似乎呈指数增长。这是正常的吗？我希望 CoreData 能够很好地处理大型数据集。您对处理如此庞大的数据集有更好的建议吗？我想知道 Dictionary apps 是如何工作的。

我的控制台输出在这里:

-2012-03-26 22:19:28.126 TweetReader[3668:707] Done 1000
-2012-03-26 22:19:40.335 TweetReader[3668:707] Done 2000
-2012-03-26 22:19:55.136 TweetReader[3668:707] Done 3000
-2012-03-26 22:20:18.569 TweetReader[3668:707] Done 4000
-2012-03-26 22:20:50.166 TweetReader[3668:707] Done 5000
-2012-03-26 22:21:30.284 TweetReader[3668:707] Done 6000
-2012-03-26 22:22:19.096 TweetReader[3668:707] Done 7000
-2012-03-26 22:23:16.091 TweetReader[3668:707] Done 8000
-2012-03-26 22:24:21.321 TweetReader[3668:707] Done 9000
-2012-03-26 22:25:35.017 TweetReader[3668:707] Done 10000
-2012-03-26 22:26:57.250 TweetReader[3668:707] Done 11000
-2012-03-26 22:28:27.563 TweetReader[3668:707] Done 12000
-2012-03-26 22:30:06.202 TweetReader[3668:707] Done 13000
-2012-03-26 22:31:52.645 TweetReader[3668:707] Done 14000

这是我保存到 CoreData 中的代码:

for (NSInteger i = 1; i <= 200000; i++) {

NSAutoreleasePool * myPool = [[NSAutoreleasePool alloc] init];

Tweet *tweetie = [NSEntityDescription insertNewObjectForEntityForName:@"Tweet" inManagedObjectContext:self.managedObjectContext];
    tweetie.name = [NSString stringWithFormat:@"%10d",i];
    tweetie.message =[NSString stringWithFormat:@"%10d",i];
    // Save the context after 1000 objects.
    if (! (i % 1000)) {
        NSError *error;
        NSLog(@"Done %d",i); 
        if (![managedObjectContext save:&error]) {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }

        [myPool release];
    }
}

Answer 1

嘿，如果你有 200k 条消息，首先要找到适合每条消息长度的最佳存储空间。这将是反复试验，我发现 3000 是最佳的。每 3000 次执行 [保存上下文] 例如:

      for(i=0; i<num of objects;i++)
      { // form the object to be saved in context

      if(i%3000==0){ // save the num of records , optimum value
        NSError *error;
        NSLog(@"saved rec nu %d",i);
        if (![context save:&error]) {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
            return NO;
       }

        [context processPendingChanges];// most important thing , if not objects will 
              // keep adding in context and time would for insertion would drastically increase.
     }
        //for last set of the objects which are less than 3000
        NSError *error;
        NSLog(@"saved rec nu %d",i);
        if (![context save:&error]) {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
            return NO;



    }

如果有什么事请告诉我