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From Oystein.Grov...@Sun.COM (Øystein Grøvlen)
Subject Re: [jira] Commented: (DERBY-239) Need a online backup feature that does not block update operations when online backup is in progress.
Date Mon, 31 Oct 2005 21:05:29 GMT

I agree that option 1 is to be preferrable.  I do not think there is
any need for transactional behavior for backup.  

--
Øystein

>>>>> "ST(" == Suresh Thalamati (JIRA) <derby-dev@db.apache.org> writes:

    ST(>     [ http://issues.apache.org/jira/browse/DERBY-239?page=comments#action_12356240
] 
    ST(> Suresh Thalamati commented on DERBY-239:
    ST(> ----------------------------------------

    ST(> What to do if backup is started in a transaction that  already has unlogged operations
executed?

    ST(> In  previous discussions about online backup, it was concluded that existing 
    ST(> backup procedures calls will WAIT for the transaction with unlogged 
    ST(> operations to commit before proceeding with the backup. One issue that was
    ST(> missing from the discussion was, what to do if user starts a backup 
    ST(> in the same transaction that has unlogged operations executed before the backup
call. 
    ST(> WAIT will  not be an acceptable option here, because backup call will wait forever.


    ST(> I can think of two ways this issue can be addressed:

    ST(> 1) Add a restriction that backup procedures can only be called in a brand
    ST(>    NEW transaction. And also implicitly commit the backup transaction at the end
of the 
    ST(>    backup. Commit is not required as such to solve this problem, but it would
    ST(>    be cleaner because backup itself is not a rollback-able operation. 
  
    ST(> 2) Make backup procedures fail, if transaction that it is started in 
    ST(>    contains unlogged operations.


    ST(> I am inclined towards implementing the first option. Any comments/suggestion 
    ST(> will be appreciated. 


    ST(> Thanks
    ST(> -suresht


    >> Need a online backup feature  that does not block update operations   when online
backup is in progress.
    >> --------------------------------------------------------------------------------------------------------
    >> 
    >> Key: DERBY-239
    >> URL: http://issues.apache.org/jira/browse/DERBY-239
    >> Project: Derby
    >> Type: New Feature
    >> Components: Store
    >> Versions: 10.1.1.0
    >> Reporter: Suresh Thalamati
    >> Assignee: Suresh Thalamati
    >> Attachments: onlinebackup.html, onlinebackup_1.diff
    >> 
    >> Currently Derby allows users to perfoms  online backups using SYSCS_UTIL.SYSCS_BACKUP_DATABASE()
procedure,  but while the backup is in progress, update operations are temporarily blocked,
but read operations can still proceed.
    >> Blocking update operations can be real issue specifically in client server environments,
because user requests will be blocked for a long time if a 
    >> backup is in the progress on the server.

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-- 
Øystein


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