Re: [PATCH 00/11] [RFC] config-batch: a new builtin for tools querying config

[Derrick Stolee <stolee@gmail.com>]

On 2/4/2026 7:04 PM, brian m. carlson wrote:
> On 2026-02-04 at 14:19:52, Derrick Stolee via GitGitGadget wrote:
>> This RFC explores a new git config-batch builtin that allows tools to
>> interact with Git's config data with multiple queries using a single
>> process. This is an orthogonal alternative to the effort to create a stable,
>> linkable config API. Both approaches have different strengths.
>>
>> My main motivation is the performance of git-credential-manager on Windows
>> platforms as it can call git config get dozens of times. At 150-200ms per
>> execution, that adds up significantly, leading to multiple seconds just to
>> load a credential that already exists. I believe that there are other
>> benefits to having this interface available, but I can't recall any
>> specifics at the moment.

>>  * Is this a worthwhile feature to add to Git?
> 
> Git LFS has the same needs, but I believe it can use `git config -l -z`
> to do that and parse the config options itself.  If this is just config
> fetching, I'm not sure of the additional utility that such a feature
> would add.  If that interface _almost_ meets your needs, could we add
> functionality there instead of a new interface?

This is a good suggestion to look into as a potentially-easier solution.

There may be some work required on the consumer to interpret multiple
values and the right inheritance rules. This is relatively minor
compared to attempting a full parser with complicated 'includeIf'
logic.
 > If you need to set many keys, I'm curious as to why that is.

I know that the credential manager does more than just query the config,
but also sets and unsets config. The full interface is here [1]. However,
the performance-critical parts may not require mutating configuration
values, and hence such a 

[1] https://github.com/git-ecosystem/git-credential-manager/blob/main/src/shared/Core/GitConfiguration.cs#L31

Thanks for the pointer to git-lfs as a similar use case. I see that it
has a way to get the full list of config values [2] with '-l' (but not
'-z'). It also has methods for getting values on a per-key (or even
per-file) basis. I have not tracked the uses of config code into its
consumers to know how often one is used over the other.

[2] https://github.com/git-lfs/git-lfs/blob/bb65882304a655ffa8abf2be6922e53ff18af5a5/git/config.go#L208

Thanks,
-Stolee