D5345: sparse-revlog: enabled by default

lothiraldan (Boris Feld) phabricator at mercurial-scm.org
Sat Dec 1 12:13:22 UTC 2018


lothiraldan added a comment.


  In https://phab.mercurial-scm.org/D5345#79390, @pulkit wrote:
  
  > Thanks for all the numbers and a detailed commit message \o/. Can you help finding answers to following extra questions?
  >
  > - What will be effect on existing repositories which don't convert to sparse revlog due to some reasons?
  
  
  The default only affects the creation of new repositories. Nothing will change for existing repository.
  
  > - If enabled by default in 4.9, will a user who uses some old mercurial like 4.6 or 4.0 will be able to clone a repository created by hg-4.9?
  
  Sure, as for the previous changes (eg: general-delta), everything is fully compatible over the wire. Mercurial 1.9 could successfully pull and push from a 4.9 server using sparse-revlog.
  
  > - Will a client who is non-sparse revlog enabled be able to interact with a server who is sparse revlog enabled?
  
  Absolutely, same as for the previous requirements introduction.
  
  > I am not following the work closely so these questions.
  > 
  >> It now seems mature enough to be enabled by default.
  > 
  > While I don't know much about revlog internals, I do see a lot of patches related to sparse revlog being pushed in this cycle which is great. The concern is that those patches are not yet a part of release. In other words, I am not feeling confident that it's much tested yet.
  
  There is a chicken and eggs issue here. We won't get much more testing until it is turned on by default. We are doing it early in the cycle to increase the amount of time it will be tested. 4.9 is two months away, we can always revert the default before 4.9 if we are not confident enough.
  
  In addition, the most radical changes happened in 4.8, we are just doing minor adjustment here.
  
  Finally, we are backporting these patch to make sure they get tested on a large repository using sparse-revlog. So by the time 4.9 is released they would have run in production for a while.
  
  > Irrespective of whether it become part of 4.9 or not, thanks for the awesome work on improving existing revlog storage.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D5345

To: lothiraldan, #hg-reviewers
Cc: pulkit, mjpieters, mercurial-devel


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