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Proposed change to skel representation

From: Greg Hudson <ghudson_at_MIT.EDU>
Date: 2002-07-29 09:11:39 CEST

While working on skip-deltas, I needed on a couple of occasions to
db_dump Subversion database files and examine the skels. I found it
rather confusing to find in the structure document things like:

  DIFF ::= ("svndiff" VERSION STRING-KEY) ;

but then in the database things like:

  ("svndiff" 1 0 2 1a)

Even after I figured out that atoms beginning with a digit were
length-counted and atoms starting with a letter weren't, it was
difficult to wrap my head around that as I read the database.

If we believe this is worth changing for easier debuggability, it
would probably be best to do so before 1.0. We can change it in a
phased backward-compatible manner like we've done with date formats.
Explicit atoms could be represented as:

  :count:data

During the transition phase, atoms beginning with a digit will still
be represented explicitly, so that existing databases can work. So
the above example would look like:

  ("svndiff" :1:0 :2:1a)

At some point in the future, after everyone is presumed to have dumped
and reloaded their databases (perhaps waiting until a more important
db change forces a dump and load), we can start leaving atoms
beginning with a digit alone, and the above example would change to:

  ("svndiff" 0 1a)

This is an easy bit of work; please let me know (by voting, I guess)
whether I should just do it or just leave well enough alone.

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Received on Mon Jul 29 09:12:13 2002

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