[elephant-devel] Re: Live backup

[Ian Eslick]

Copying all the data from a store isn't a big problem, copying a store  
without creating inconsistent state while the application continues to  
run is the challenge I thought the user was interested in.  If you do  
it at the application level within a transaction (even if it did fit  
in memory) you would either implicitly halt all activity or constantly  
be aborted by any write operation anywhere in the db.

While there is not an 'elephant' level way to do live backups, each  
underlying data store has it's own methods as pointed out by Henrik  
and Alex for the SQL cases.

Berkeley DB also supports low-level hot backups if you know that your  
OS reads file pages atomically.  (http://www.oracle.com/technology/documentation/berkeley-db/db/ref/transapp/archival.html 
)  For an example see the source code for db_hotbackup in the BDB  
distribution.

Ian

On Dec 11, 2007, at 7:43 AM, Alex Mizrahi wrote:

> IE> policy for object creation and just copy all the objects from one
> IE> store to another.
>
> if bdb has serializable isolation level be default, woudn't it be  
> enough
> just to copy data within transaction?
>
>
>
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