glossary: add "commit graph" description
Git has an additional "commit graph" capability that supplements the normal commit object's directed acyclic graph (DAG). The supplemental commit graph file is designed for speed of access. Describe the commit graph both from the normative DAG view point and from the commit graph file perspective. Also, clarify the link between the branch ref and branch tip by linking to the `ref` glossary entry, matching this commit graph entry. The commit-graph file is also distinguished by its hyphenation. Subsequent commit catches the few cases where the hyphenation of commit-graph was missing. Signed-off-by: Philip Oakley <philipoakley@iee.email> Signed-off-by: Taylor Blau <me@ttaylorr.com>
Philip Oakley committed
Oct 29, 2022 at 17:41 UTC
4973726c5dfbaebdab95dab52b4c05b2a637d3fb
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Documentation/glossary-content.txt
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@@ -20,7 +20,7 @@
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[[def_branch]]branch::
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A "branch" is a line of development. The most recent
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<<def_commit,commit>> on a branch is referred to as the tip of
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- that branch. The tip of the branch is referenced by a branch
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+ that branch. The tip of the branch is <<def_ref,referenced>> by a branch
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<<def_head,head>>, which moves forward as additional development
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is done on the branch. A single Git
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<<def_repository,repository>> can track an arbitrary number of
@@ -75,6 +75,21 @@ state in the Git history, by creating a new commit representing the current
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state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>>
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to point at the new commit.
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+[[def_commit_graph_general]]commit graph concept, representations and usage::
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+ A synonym for the <<def_DAG,DAG>> structure formed by the commits
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+ in the object database, <<def_ref,referenced>> by branch tips,
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+ using their <<def_chain,chain>> of linked commits.
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+ This structure is the definitive commit graph. The
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+ graph can be represented in other ways, e.g. the
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+ <<def_commit_graph_file,"commit-graph" file>>.
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+
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+[[def_commit_graph_file]]commit-graph file::
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+ The "commit-graph" (normally hyphenated) file is a supplemental
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+ representation of the <<def_commit_graph_general,commit graph>>
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+ which accelerates commit graph walks. The "commit-graph" file is
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+ stored either in the .git/objects/info directory or in the info
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+ directory of an alternate object database.
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+
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[[def_commit_object]]commit object::
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An <<def_object,object>> which contains the information about a
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particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer,