Re: Some questions about Reiser4

[Hans Reiser <reiser@namesys.com>]

Fred -- Speed Up -- wrote:

>Hi there ;)
>
>I've read the full official documentation about Reiser4 on the Namesys website,
>
I recommend reading it again.

> but some question still remain unanswerd. I'd like you to help me solving them :
>
>- Firstly the trees. I read that the it (the storage one, not the semantic side) grew on top, which makes the key grow in lenght.
>
The key is constant in size.

> But what about fanout ? When a file has been deleted, can its former key be freed and reused so that the tree keeps balanced ? Does Reiser4 otpimize the tree by storing small files together in a part of the tree, or directories, or whatever organisation : when a file is being written, does Reiser4 give it the first key it finds, or does a segragation exist in order to improve performance ? For instance, small temp files are created and deleted numbers of times, does a special part of the tree keep those temp files so that only a little part of the tree is constantly changing ?
>
no.

>- What do you call a 'graph' when speaking about the structure the semantic layer uses to resolve paths ? How does this part really work (it is not formally spcified in the doc) ?
>- How about folders : what status do they have ? They may be stored as other files, as they have to keep their own properties, but their information (the folder's files and subfolder list) is being kept in the semantic layer's graph : how do you handle with this ?
>- Why do you need to store the locality_id in the key ?
>
So that objects in the same locality are near each other in their tree 
order.

>- How do you handle with big files wich do not fit in contiguous bloc space, so they need more than one extended pointer ? How are those other pointers stored ?
>
One after another in the extent items.

>- B+Trees are simply BTrees that do not use BLOBs, am I right ?
>
No.  B+trees store only pointers in their internal nodes.  A Btree might 
store data smaller than a node inside one of the internal nodes of the 
tree along with several other data items.  That means it is not a B+tree 
and it is not using a BLOB either.

>- Dancing trees are simply Balanced Trees wich are only modified in an event of memory pressure, don't they ?
>
No.

>- How is the developement ? I mean, should we await the Reiser 4.0 release this summer, or do you need some more time ? What features will be included in 4.0 and which will be left for 4.1 ? Will the packer be ready for release as Reiser 4.0 comes out ?
>
The repacker will be in 4.1.

>
>My goal is to provide a french, complete and exact FDL licensed documentation about Reiser4, hopefully before the next month. I'd just like you to help me, I'm sure you'll be able to.
>
>
>Thank you in advance,
>
>Fred
>  
>


-- 
Hans