[ZODB-Dev] Blob directory structure scalability limits

[Christian Theune]

Hi,

On Fri, Jun 20, 2008 at 07:55:17PM +0200, Andreas Jung wrote:
>
>
> --On 19. Juni 2008 14:31:47 +0200 Martijn Faassen 
> <faassen at startifact.com> wrote:
>
>> Hi there,
>>
>> On Thu, Jun 19, 2008 at 1:38 PM, Christian Theune <ct at gocept.com> wrote:
>> [snip]
>>> We propose to keep both implementations around and allow to select which
>>> one to use. We would extend the FileSystemHelper to abstract the two
>>> strategies.
>>
>> Could the default be to choose the more scalable one, or would this
>> lead to backwards compatibility issues?
>>
>>
>
> Good point especially because Zope 2.11 is now inofficially released and  
> people will start using blobs based on the limited directory layout...so  
> how would a migration look like when people do encounter the current  
> limitations?

It's 100% backwards compatible. When the old layout is used a warning is
issued with a hint to migrate but I continue to fully support the old data
structures. When a new directory is started, the new layout becomes the
default.

Migration comes in the form of a command line script that can convert the old
structure to the new one. It requires the database to be offline, but I'm
working hard to make it reasonably fast. The script will be available ...
later today.


Christian


-- 
Christian Theune · ct at gocept.com
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Zope and Plone consulting and development