view mercurial/helptext/bundlespec.txt @ 45065:b8f4ead9fa49

commitctx: reorder some conditional for efficiency in _filecommit

Checking if a dict is empty will be faster than comparing text. I don't expect
it to be a huge performance win, but still a good (but gratuitous) cleanup to
do while we are at it.

This is part of a larger refactoring/cleanup of the commitctx code to clarify
and augment the logic gathering metadata useful for copy tracing. The current
code is a tad too long and entangled to make such update easy. We start with
easy and small cleanup.

Differential Revision: https://phab.mercurial-scm.org/D8701

Mercurial supports generating standalone "bundle" files that hold repository
data. These "bundles" are typically saved locally and used later or exchanged
between different repositories, possibly on different machines. Example
commands using bundles are :hg:`bundle` and :hg:`unbundle`.

Generation of bundle files is controlled by a "bundle specification"
("bundlespec") string. This string tells the bundle generation process how
to create the bundle.

A "bundlespec" string is composed of the following elements:

type
    A string denoting the bundle format to use.

compression
    Denotes the compression engine to use compressing the raw bundle data.

parameters
    Arbitrary key-value parameters to further control bundle generation.

A "bundlespec" string has the following formats:

<type>
    The literal bundle format string is used.

<compression>-<type>
    The compression engine and format are delimited by a hyphen (``-``).

Optional parameters follow the ``<type>``. Parameters are URI escaped
``key=value`` pairs. Each pair is delimited by a semicolon (``;``). The
first parameter begins after a ``;`` immediately following the ``<type>``
value.

Available Types
===============

The following bundle <type> strings are available:

v1
    Produces a legacy "changegroup" version 1 bundle.

    This format is compatible with nearly all Mercurial clients because it is
    the oldest. However, it has some limitations, which is why it is no longer
    the default for new repositories.

    ``v1`` bundles can be used with modern repositories using the "generaldelta"
    storage format. However, it may take longer to produce the bundle and the
    resulting bundle may be significantly larger than a ``v2`` bundle.

    ``v1`` bundles can only use the ``gzip``, ``bzip2``, and ``none`` compression
    formats.

v2
    Produces a version 2 bundle.

    Version 2 bundles are an extensible format that can store additional
    repository data (such as bookmarks and phases information) and they can
    store data more efficiently, resulting in smaller bundles.

    Version 2 bundles can also use modern compression engines, such as
    ``zstd``, making them faster to compress and often smaller.

Available Compression Engines
=============================

The following bundle <compression> engines can be used:

.. bundlecompressionmarker

Examples
========

``v2``
    Produce a ``v2`` bundle using default options, including compression.

``none-v1``
    Produce a ``v1`` bundle with no compression.

``zstd-v2``
    Produce a ``v2`` bundle with zstandard compression using default
    settings.

``zstd-v1``
    This errors because ``zstd`` is not supported for ``v1`` types.