[cvsnt] Re: Performance problems

Tony Hoyle tmh at nodomain.org
Tue Dec 28 18:07:59 GMT 2004


Nitzan Shaked wrote:
> Yes and no. I *am* suggest to change the RCS file format, but it *will*
> remain self-contained. Re-read my suggestion: I am suggesting to modify the
> file itself, not use another file. The "use another file" was in the context
> of how to do very quick per-file tags. What I wrote was that you could also
> quickly add tags to the files themselves (if you don't want other metadata
> files), and suggest to how do it quickly. But still in the same file.

Modifying the file itself simply isn't safe.  File reads and writes are 
not atomic (technically neither are renames but they're at least done in 
a single operation in the FSD rather than several, and NTFS keeps a 
journal).

What you're taking about is an insert into the beginning of the file - 
that can't be done without rewriting the whole file anyway.  Working on 
a live file in this way is a recipe for disaster.

You couldn't implement a scheme as you suggest without completely 
ditching the RCS file format - which is a rewrite of 50-70% of of the 
CVS code, since it's tightly integrated...  It's better to go all the 
way to an SQL database for that effort.

Tony



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