gistfile1.txt

- (void) deleteTweetsOlderThan:(int)inMaxToKeep
{
	NSArray* recent_ids = [RFTweet tweetIDsReversedForCollectionID:self.collectionID];
	if ([recent_ids count] > inMaxToKeep) {
		FMDatabaseQueue *queue = …
		
		[queue inDatabase:^(FMDatabase *db) {
            
            if (inMaxToKeep > 0) {
                NSNumber* last_tweet_id = [recent_ids objectAtIndex:inMaxToKeep - 1];
                [db executeUpdate:@"DELETE FROM mappings WHERE tweet_id < ? AND collection_id = ?", last_tweet_id, self.collectionID];
            }
            else {
                [db executeUpdate:@"DELETE FROM mappings WHERE collection_id = ?", self.collectionID];
            }
        };
        
		[queue inTransaction:^(FMDatabase *db, BOOL *rollback) {
            for (int i = inMaxToKeep; i < [recent_ids count]; i++) {
                @autoreleasepool {
                    NSNumber* tweet_id_to_delete = [recent_ids objectAtIndex:i];
                    if (![RFMapping findWithColumn:@"tweet_id" value:tweet_id_to_delete accountID:self.accountID]) {
                        [db executeUpdate:@"DELETE FROM tweets WHERE id = ?", tweet_id_to_delete];
                    }
                }
            }
		}];
	}
}





or you could use inSavePoint: