TimesTen备份文件名解读

一个备份的输出如下：
$ ll
total 44292
-rw——-. 1 timesten timesten 28867176 Oct 18 22:05 sampledb_1122.0.bac
-rw——-. 1 timesten timesten 16480256 Oct 18 22:05 sampledb_1122.0.bac0
-rw——-. 1 timesten timesten 720 Oct 18 22:05 sampledb_1122.sta
虽然大致猜的到，不过还是听听权威的解释：

The .bac file is essentially a copy of the most recent checkpoint file (ds0/ds1) while the .bacxyz file is a single file that is a merge of all the transaction log files (tt41data.lognnnnnn files) needed to recover from that checkpoint file. So depending on the state of your database (in terms of the number of log files present on disk and which of them are actually required) at the time you take the backup the .bacxyz file may vary in size from very small to very large. If you want to ensure that the .bacxyz file has the smallest possible size you should issue a checkpoint manually, and wait for it to finish, before running the ttBackup command.