changeset 4:561edf852797

More detail on file format changes, from post by MM to mercurial.general.
author Jim Hague <jim.hague@icc-atcsolutions.com>
date Sun, 21 Dec 2008 21:42:58 +0000
parents 175493e0e457
children 2ec53c0ed5d8
files Hg.txt
diffstat 1 files changed, 13 insertions(+), 5 deletions(-) [+]
line wrap: on
line diff
--- a/Hg.txt	Sun Dec 21 21:42:23 2008 +0000
+++ b/Hg.txt	Sun Dec 21 21:42:58 2008 +0000
@@ -584,8 +584,16 @@
 changes after that point. These changes are then copied over and
 applied.
 
-The Mercurial revlog format has proved remarkably durable. Over the
-lifetime of Mercurial, there have been just two changes to the file
-format. And one of those (a very recently change at the time of
-writing, yet to appear in a release version) is a very small change to
-filename storage required to deal with Windows-specific issues.
+The Mercurial revlog format has proved remarkably durable. Since the
+first release of Mercurial in April 2005, these have been a total of 5
+changes to the file format. However, of those, all but one have been
+changes to the handling of file names. The most recent change, in
+October 2008, and its predecessor in December 2006, were both
+introduced purely to cope with Windows specific issues. The one change
+that touched the datastructures described above was in April 2006. The
+format introduced, RevLogNG, changed only the details of index data
+held, not the overall design. The chief Mercurial developer, Matt
+Mackall, notes that the code in present-day Mercurial devoted to
+reading the old format comprises 28 lines of Python. Compared with,
+say, the early tribulations of Subversion and the switch from bdfs to
+fsfs, this is an impressive record.