Re: is commitGraph useful on the server side?

From: Derrick Stolee <stolee@gmail.com>
Date: Oct 22, 2019, 19:44 UTC
Message-ID: <e0e294a7-bd3c-2174-a922-c5893b0945c2@gmail.com>
In-Reply-To: <20191022165112.GA4960@chatter.i7.local>

On 10/22/2019 12:51 PM, Konstantin Ryabitsev wrote:

Show 5 quoted lines

> Hi, all:
> 
> I've read the docs on commitGraph and it's not 100% clear to me if turning it on and generating commit graphs would be useful on the server-side. I know it's going to be enabled by default and automatically generated whenever "git gc" runs, so I'm trying to figure out if it'll be useful for git-daemon operations.
> 
> Thanks in advance for your help.

I've CC'd Taylor Blau for more information here.

I'm biased, but I think the commit-graph is generally really good to have in almost all cases. I actually do not know of a good reason to _not_ have it.

If you are managing reachability bitmaps, then most of the server-side stuff will use the bitmaps instead. However, creating those bitmaps will be slightly faster with the commit-graph.

If you don't use bitmaps, then the commit-graph will help fetch negotiation and many other commit-walk experiences.

If you have a lot of machinery around your server maintenance, then you can schedule commit-graph updates more frequently than bitmap computations, and you would get benefit by parsing commits faster in the zone "above" the bitmaps.

Thanks, -Stolee