On 9/6/2010 9:32 AM, Maison Mo wrote:
Hello dear derby developers,
I have a question about database backup.
According to admin guide, there are two methods for that operation :
1 - freeze the DB with SYSCS_UTIL.SYSCS_FREEZE_DATABASE and perform a
(hopefully quick) external copy of database files ; then UNFREEZE
2 - Use SYSCS_UTIL.SYSCS_BACKUP_DATABASE(...)
I wonder what happens when commits are performed during the backup.
- With method 1 I expect the commits to hang until the unfreeze
- With method 2 what happens exactly ? Does the commit go into the
backup ? Always ? Never ? Does it depends on the table(s) on which the
commit is performed ?
Assuming you are using a current version, I believe you are safe using
online-backup which should not block which was introduced in 10.2[1].
There are a few exceptions regarding unlogged operations, see online
backup documentation [2]:
Uncommitted transactions do not appear in the backed-up database and new
commits that occur during the backup will not appear in the backup.
Thanks Kathey
[1] https://issues.apache.org/jira/browse/DERBY-239
[2]http://db.apache.org/derby/docs/10.5/adminguide/cadminhubbkup01.html
