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Feature
-------
Object Count
Summary
-------
An efficient mechanism to retrieve the number of objects per directory
or volume.
Owners
------
Vijaikumar M <vmallika@redhat.com>
Sachin Pandit <spandit@redhat.com>
Current status
--------------
Currently, the only way to retrieve the number of files/objects in a
directory or volume is to do a crawl of the entire directory/volume.
This is expensive and is not scalable.
The proposed mechanism will provide an easier alternative to determine
the count of files/objects in a directory or volume.
Detailed Description
--------------------
The new mechanism proposes to store count of objects/files as part of an
extended attribute of a directory. Each directory's extended attribute
value will indicate the number of files/objects present in a tree with
the directory being considered as the root of the tree.
The count value can be accessed by performing a getxattr(). Cluster
translators like afr, dht and stripe will perform aggregation of count
values from various bricks when getxattr() happens on the key associated
with file/object count.
Benefit to GlusterFS
--------------------
- Easy to query number of objects present in a volume.
- Can serve as an accounting mechanism for quota enforcement based on
number of inodes.
- This interface will be useful for integration with OpenStack Swift
and Ceilometer.
Scope
-----
### Nature of proposed change
- Marker translator to be modified to perform accounting on all
create/delete operations.
- A new volume option to enable/disable this feature.
### Implications on manageability
- A new volume option to enable/disable this feature.
- A new CLI interface to display this count at either a volume or
directory level.
### Implications on presentation layer
None
### Implications on persistence layer
None
### Implications on 'GlusterFS' backend
None
### Modification to GlusterFS metadata
A new extended attribute for storing count of objects at each directory
level.
### Implications on 'glusterd'
TBD
How To Test
-----------
TBD
User Experience
---------------
TBD
Dependencies
------------
None
Documentation
-------------
TBD
Status
------
Design Ready
Comments and Discussion
-----------------------
|
