[ZODB-Dev] [Plone-Users] question about using repozo and blob storage

[Ralf Hemmecke]

If this is of any interest... (see the suggestion below)

Move of discussion from plone-users
http://plone.293351.n2.nabble.com/question-about-using-repozo-and-blob-storage-tp5016465p5016465.html

Ralf

-------- Original Message --------
Subject: Re: [Plone-Users] question about using repozo and blob storage
Date: Fri, 7 May 2010 10:05:59 -0700 (PDT)
From: ajung <lists at zopyx.com>
To: plone-users at lists.sourceforge.net


This list is the wrong place for such deep ZODB related discussions. Suggest
this on the zodb-dev list.

-aj


Ralf Hemmecke-2 wrote:
> 
> On 05/07/2010 06:40 PM, ajung wrote:
>> 
>> Blobs are - as David explained - a _core_ component of the ZODB. Content
>> stored through the file storage or blob storage are handled and treated
>> in
>> the same way to the application. If you want to write a SCM-based backend
>> for ZODB....I am not sure how far you will get and if it would be
>> reasonably
>> fast and without major architectural issues.
> 
> I understand that meta data lives still in ZODB. And I wouldn't want to
> suggest that people deal with the blobs in any other way than through
> plone. One should only be able to have read access to the blobstorage
> (if it's not through plone, otherwise disaster may happen).
> 
> I haven't actually looked into how blobs are actually stored on the file
> system, i.e., in particular what name they will have and whether the
> file system structure is the same as the folder hierarchy inside plone.
> But that doesn't actually matter.
> 
> I assume that they are stored in some directory in a directory for
> blobs, let's call it blobdir.
> 
> I speak now for git, but other SCMs are quite similar (maybe not svn).
> 
> This blobdir is turned into a repository by simply saying "git init".
> 
> Then when plone stores a file, it will write it into (a subdir of)
> blobdir. With GIT behind that should read:
> 
>   (1)  write it into blobdir and then
>   (2) git add FILENAME"
>   (3) git commit -m "some message"
> 
> That's it.
> 
> If the user uploads a new file to plone, then plone doesn't have to care
> about renaming the old file and storing the new, it simply has to do THE
> SAME steps (1)..(3) as above. I call that easier.
> 
> Maybe packing is a bit more difficult and depends on the SCM in
> question. For git it would be a simple "git filter-branch" (of course
> with appropriate parameters) followed by "git gc".
> 
> Just my two cents. I would find such a GIT backend wonderful. But I've
> no experience with how that blob stuff is actually done through
> plone/zope. So sorry if I cannot provide any code.
> 
> Ralf
> 
> ------------------------------------------------------------------------------