20.04.2013 21:24, Nikolay Samofatov wrote:
> Hello, All!
>
> We use NBACKUP for physical replication of the databases. For that we added 2
> features:
>
> 1) We only read one sector (with header) of each page when scanning for
> changes. This is helpful for
> SSD media and might provide 4x-32x speed up.
> This is probably not important for FB3, as it will have SCN pages, but is
> very useful optimization
> for 2.X ODS.
>
> 2) We added option into NBACKUP utility to create change set based on
> baseline GUID rather than level.
>
> -B <level>|<GUID> <database> [<filename>] Create incremental backup
>
> This is the same GUID that is displayed in GSTAT output:
>
> Database backup GUID: {35F5915A-4A62-4A27-AD91-6FB0EBDCCF11}
>
> To update offline copy of the database over WAN we use the following
> procedure in a shall script:
> - obtain baseline GUID of the database using GSTAT -h
> - pull changes using SSH+NBACKUP using baseline GUID
> - if pull is successful apply changes to a local copy
> - if incremental pull fails get clean copy of the database using "NBACKUP -B
> 0", CAT and DD (we have
> implemented download resume in a shall script)
>
> Pull might fail if baseline with given GUID doesn't exist in the database (it
> was restored from gbak
> backup, etc).
>
> This idea of using nbackup for exact this purpose was in the original design,
> data formats, etc
> although it was never completed. Changes do not affect engine code.
>
> If there are no objections to this design I will ask Dmitry Starodubov to
> port this code to FB3 and
> submit a patch for integration.
The feature (part 2) is committed (with little changes) into master.
Basic tests show it works :) If anyone have idea how to improve it - you are
welcome.
For example, we could introduce special switch to query backup GUID of target
database
to pass in into backup automatically.
Regards,
Vlad
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