comparison mercurial/help/config.txt @ 41818:f6eff9e4de80

storage: introduce a `revlog.reuse-external-delta-parent` config

As pointed in c59987ab96b4, we had no simple way to get a client to not blindly
reuse the delta parent from a bundle. Instead one had to rely on a side effect
of the deprecated `format.generaldelta` configuration.

We introduce an explicit `revlog.reuse-external-delta-parent` configuration
option (default to True) to control this behavior. If the option is not set,
`format.generaldelta` still control this behavior.

To test the new option, we convert a couple of place where `generaldelta` have
been used for its side effects.

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    revlog compression. This option is enabled by default.

    Turning this option off can result in large increase of repository size for
    repository with many merges.

``server``
----------

Controls generic server settings.

41818:f6eff9e4de80

    revlog compression. This option is enabled by default.

    Turning this option off can result in large increase of repository size for
    repository with many merges.

``revlog.reuse-external-delta-parent``
    Control the order in which delta parents are considered when adding new
    revisions from an external source.
    (typically: apply bundle from `hg pull` or `hg push`).

    New revisions are usually provided as a delta against other revisions. By
    default, Mercurial will try to reuse this delta first, therefore using the
    same "delta parent" as the source. Directly using delta's from the source
    reduces CPU usage and usually speeds up operation. However, in some case,
    the source might have sub-optimal delta bases and forcing their reevaluation
    is useful. For example, pushes from an old client could have sub-optimal
    delta's parent that the server want to optimize. (lack of general delta, bad
    parents, choice, lack of sparse-revlog, etc).

    This option is enabled by default. Turning it off will ensure bad delta
    parent choices from older client do not propagate to this repository, at
    the cost of a small increase in CPU consumption.

    Note: this option only control the order in which delta parents are
    considered.  Even when disabled, the existing delta from the source will be
    reused if the same delta parent is selected.

``server``
----------

Controls generic server settings.