Re: [Gnu-arch-users] Re: [PATCH] arch speedups on big trees

[Chris Mason]

On Thu, 2004-01-08 at 20:49, Tom Lord wrote:
>     > From: Chris Mason <address@hidden>
> 
>     > 1) Do inode signatures actually help performance in the current form?  I
>     > think they make most uses slower (except revision libraries).  
> 
> 
> A while back, briefly, they improved performance for implicit or
> tagline trees.  Currently, they do impose a new cost -- for the return
> of increasing safety.  The safety concern is worth it, I think --
> those costs aren't likely to go away.
> 

Ok, the safety point of view is different.  If we want the inode sigs
for safety or other cool features, we just need to make it faster to
update them.

> (The other pending issue is that they hork some NFS implementations.
> That has to be fixed.)
> 
>     > 2) Does a reverse mapping safely allow arch_apply_changeset to skip
>     > whole tree inventories?  
> 
> Unlikely but I haven't dug into it yet.

By definition of the changeset, I think it has to allow a partial
inventory.  Either the changeset somehow describes all files and ids
involved in it, or the format is  broken.

In the end, I agree with Miles about putting the inode sigs and id
mappings into an indexed database file.  It adds complexity, but the end
result seems worth it.

-chris