Re: question on performance evaluation of beagle's indexing

On 02/04/2008, D Bera <dbera web gmail com> wrote:
>  Beagle stores its bookkeeping information per file in the extended
>  attributes of the files or if that fails, in an sqlite database. There
>  is a folklore that using the extended attributes is significantly
>  faster than the sqlite database (disk access vs sqlite access). But
>  depending on disk I/O speed and other system load, sqlite access could
>  sometimes be faster IMO. For simplicity we ignore the tradeoff and
>  always suggest and prefer extended attributes over sqlite. You can
>  force sqlite by setting BEAGLE_DISABLE_XATTR.

Note that the xattr performance is also FS-dependent. Different
file-systems have different ways of storing xattrs. Ext2/3 store it
either in the inode, or in a separate block if more space is required.
ReiserFS stores each xattr as a (hidden) file in /.reiserfs_priv (and
counts on its tail-packing for efficiency), and XFS has 3 methods
(in-inode for small numbers, and using B+ trees in the most complex
case -- the method depends on the number/size of xattrs, IIRC).

Arun Raghavan

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