git/Documentation
Derrick Stolee 1771be90c8 commit-graph: merge commit-graph chains
When searching for a commit in a commit-graph chain of G graphs with N
commits, the search takes O(G log N) time. If we always add a new tip
graph with every write, the linear G term will start to dominate and
slow the lookup process.

To keep lookups fast, but also keep most incremental writes fast, create
a strategy for merging levels of the commit-graph chain. The strategy is
detailed in the commit-graph design document, but is summarized by these
two conditions:

  1. If the number of commits we are adding is more than half the number
     of commits in the graph below, then merge with that graph.

  2. If we are writing more than 64,000 commits into a single graph,
     then merge with all lower graphs.

The numeric values in the conditions above are currently constant, but
can become config options in a future update.

As we merge levels of the commit-graph chain, check that the commits
still exist in the repository. A garbage-collection operation may have
removed those commits from the object store and we do not want to
persist them in the commit-graph chain. This is a non-issue if the
'git gc' process wrote a new, single-level commit-graph file.

After we merge levels, the old graph-{hash}.graph files are no longer
referenced by the commit-graph-chain file. We will expire these files in
a future change.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-06-19 20:46:26 -07:00
..
config Merge branch 'ds/push-sparse-tree-walk' 2019-02-06 22:05:25 -08:00
howto Merge branch 'uk/merge-subtree-doc-update' into maint 2018-11-21 22:58:08 +09:00
RelNotes Git 2.21-rc1 2019-02-13 18:18:43 -08:00
technical commit-graph: merge commit-graph chains 2019-06-19 20:46:26 -07:00
.gitattributes
.gitignore add a script to diff rendered documentation 2018-08-06 12:30:23 -07:00
asciidoc.conf
asciidoctor-extensions.rb Documentation: implement linkgit macro for Asciidoctor 2017-01-31 12:18:18 -08:00
blame-options.txt Merge branch 'bc/blame-doc-fix' 2017-02-24 10:48:08 -08:00
build-docdep.perl
cat-texi.perl Documentation: remove unneeded argument in cat-texi.perl 2017-01-23 10:56:47 -08:00
cmd-list.perl command-list: prepare machinery for upcoming "common groups" section 2015-05-21 13:03:37 -07:00
CodingGuidelines Merge branch 'jc/how-to-document-api' 2018-10-19 13:34:05 +09:00
config.txt Merge branch 'nd/packobjectshook-doc-fix' into maint 2018-11-21 22:58:01 +09:00
date-formats.txt Merge branch 'lr/doc-fix-cet' into maint 2017-01-17 15:19:08 -08:00
diff-format.txt doc: update diff-format.txt for removed ellipses in --raw 2018-11-26 15:59:14 +09:00
diff-generate-patch.txt Documentation: improve description for core.quotePath 2017-03-02 11:40:51 -08:00
diff-options.txt Merge branch 'pw/diff-color-moved-ws-fix' 2019-01-29 12:47:53 -08:00
doc-diff Merge branch 'ma/doc-diff-usage-fix' 2019-02-06 22:05:30 -08:00
docbook-xsl.css
docbook.xsl
everyday.txto Documentation: fix linkgit references 2016-05-09 15:44:14 -07:00
fetch-options.txt Merge branch 'ab/fetch-tags-noclobber' 2018-09-17 13:54:00 -07:00
fix-texi.perl
git-add.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-am.txt Merge branch 'nd/rebase-show-current-patch' 2018-03-06 14:54:02 -08:00
git-annotate.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-apply.txt Merge branch 'nd/diff-apply-ita' 2018-06-25 13:22:36 -07:00
git-archimport.txt git-archimport.1: specify what kind of Arch we're talking about 2018-09-21 09:28:58 -07:00
git-archive.txt docs: clarify remote restrictions for git-upload-archive 2014-02-28 09:55:35 -08:00
git-bisect-lk2009.txt doc: fix ASCII art tab spacing 2018-10-23 12:23:09 +09:00
git-bisect.txt Merge branch 'ak/bisect-doc-typofix' 2018-04-25 13:28:56 +09:00
git-blame.txt diff: --indent-heuristic is no longer experimental 2017-11-02 14:51:24 +09:00
git-branch.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-bundle.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-cat-file.txt Merge branch 'dt/cat-file-batch-ambiguous' 2019-02-06 22:05:21 -08:00
git-check-attr.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-check-ignore.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-check-mailmap.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-check-ref-format.txt Doc/check-ref-format: clarify information about @{-N} syntax 2017-12-19 10:00:45 -08:00
git-checkout-index.txt
git-checkout.txt Merge branch 'ja/doc-style-fix' 2019-02-05 14:26:16 -08:00
git-cherry-pick.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-cherry.txt Documentation: revamp git-cherry(1) 2013-11-27 12:16:49 -08:00
git-citool.txt
git-clean.txt doc: typeset short command-line options as literal 2016-06-28 08:20:52 -07:00
git-clone.txt Documentation/clone: document ignored configuration variables 2018-11-16 13:15:21 +09:00
git-column.txt git-column.txt: fix section header 2018-12-26 15:29:30 -08:00
git-commit-graph.txt Doc: refer to the "commit-graph file" with dash 2018-09-27 15:29:12 -07:00
git-commit-tree.txt Merge branch 'mm/doc-tt' into maint 2016-07-28 11:25:54 -07:00
git-commit.txt git-commit.txt: better description what it does 2019-02-04 10:00:01 -08:00
git-config.txt worktree: add per-worktree config files 2018-10-22 13:17:04 +09:00
git-count-objects.txt count-objects: report alternates via verbose mode 2016-10-10 13:52:37 -07:00
git-credential-cache--daemon.txt credential-cache: close stderr in daemon process 2014-09-16 11:11:58 -07:00
git-credential-cache.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-credential-store.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-credential.txt
git-cvsexportcommit.txt
git-cvsimport.txt Merge branch 'jk/doc-cvs-update' into maint 2016-10-03 13:22:25 -07:00
git-cvsserver.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-daemon.txt daemon: add --log-destination=(stderr|syslog|none) 2018-02-05 10:30:44 -08:00
git-describe.txt git-describe.1: clarify that "human readable" is also git-readable 2018-09-21 09:32:21 -07:00
git-diff-files.txt
git-diff-index.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-diff-tree.txt diff-tree doc: correct & remove wrong documentation 2019-02-04 12:39:13 -08:00
git-diff.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-difftool.txt Document the --no-gui option in difftool 2017-02-08 13:30:28 -08:00
git-fast-export.txt fast-export: add a --show-original-ids option to show original names 2018-11-17 18:43:52 +09:00
git-fast-import.txt fast-export: add a --show-original-ids option to show original names 2018-11-17 18:43:52 +09:00
git-fetch-pack.txt Documentation: fix several one-character-off spelling errors 2018-04-09 14:15:02 +09:00
git-fetch.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-filter-branch.txt Merge branch 'nd/doc-header' 2018-05-23 14:38:22 +09:00
git-fmt-merge-msg.txt config.txt: move fmt-merge-msg-config.txt to config/ 2018-10-29 10:17:01 +09:00
git-for-each-ref.txt ref-filter: add docs for new options 2018-12-28 10:08:11 -08:00
git-format-patch.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-fsck-objects.txt
git-fsck.txt prefer "hash mismatch" to "sha1 mismatch" 2019-01-08 09:41:06 -08:00
git-gc.txt git-gc.txt: fix typo about gc.writeCommitGraph 2019-01-08 11:14:04 -08:00
git-get-tar-commit-id.txt usage: do not insist that standard input must come from a file 2015-10-16 15:27:52 -07:00
git-grep.txt grep: add -r/--[no-]recursive 2018-10-03 21:25:57 -07:00
git-gui.txt doc: git-gui browser does not default to HEAD 2017-01-13 12:23:28 -08:00
git-hash-object.txt usage: do not insist that standard input must come from a file 2015-10-16 15:27:52 -07:00
git-help.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-http-backend.txt doc: more consistency in environment variables format 2016-06-08 12:04:37 -07:00
git-http-fetch.txt http-fetch: make -a standard behaviour 2018-04-24 10:55:02 +09:00
git-http-push.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-imap-send.txt git-imap-send.txt: move imap.* to a separate file 2018-10-29 10:17:02 +09:00
git-index-pack.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-init-db.txt
git-init.txt Merge branch 'km/init-doc-typofix' 2019-02-06 22:05:21 -08:00
git-instaweb.txt git-instaweb: add Python builtin http.server support 2019-01-28 10:57:44 -08:00
git-interpret-trailers.txt Merge branch 'jk/trailer-fixes' into maint 2018-11-21 22:57:42 +09:00
git-log.txt Add 'human' date format documentation 2019-01-22 14:16:17 -08:00
git-ls-files.txt Merge branch 'ah/misc-doc-updates' 2018-05-23 14:38:23 +09:00
git-ls-remote.txt Merge branch 'bw/server-options' 2018-05-23 14:38:15 +09:00
git-ls-tree.txt Documentation: improve description for core.quotePath 2017-03-02 11:40:51 -08:00
git-mailinfo.txt Merge branch 'va/mailinfo-doc-typofix' into maint 2016-05-26 13:17:14 -07:00
git-mailsplit.txt mailsplit: support unescaping mboxrd messages 2016-06-06 11:14:43 -07:00
git-merge-base.txt doc: fix ASCII art tab spacing 2018-10-23 12:23:09 +09:00
git-merge-file.txt merge-file: clamp exit code to maximum 127 2015-10-29 12:10:23 -07:00
git-merge-index.txt
git-merge-one-file.txt
git-merge-tree.txt
git-merge.txt config.txt: move merge-config.txt to config/ 2018-10-29 10:17:03 +09:00
git-mergetool--lib.txt
git-mergetool.txt mergetool: accept -g/--[no-]gui as arguments 2018-10-25 14:01:10 +09:00
git-mktag.txt usage: do not insist that standard input must come from a file 2015-10-16 15:27:52 -07:00
git-mktree.txt Documentation: normalize spelling of 'normalised' 2018-04-09 14:15:07 +09:00
git-multi-pack-index.txt multi-pack-index: add 'verify' verb 2018-09-17 13:49:38 -07:00
git-mv.txt doc: typeset short command-line options as literal 2016-06-28 08:20:52 -07:00
git-name-rev.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-notes.txt Documentation: spelling and grammar fixes 2018-06-22 14:26:23 -07:00
git-p4.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-pack-objects.txt list-objects: consume sparse tree walk 2019-01-17 13:44:39 -08:00
git-pack-redundant.txt
git-pack-refs.txt
git-parse-remote.txt
git-patch-id.txt doc: remove unsupported parameter from patch-id 2017-07-28 14:41:32 -07:00
git-prune-packed.txt Documentation: adjust document title underlining 2014-10-13 13:35:18 -07:00
git-prune.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-pull.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-push.txt push doc: document the DWYM behavior pushing to unqualified <dst> 2018-11-14 15:27:56 +09:00
git-quiltimport.txt git-quiltimport: add --keep-non-patch option 2019-01-07 15:29:34 -08:00
git-range-diff.txt range-diff doc: add a section about output stability 2018-11-12 12:05:38 +09:00
git-read-tree.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-rebase.txt Merge branch 'ea/rebase-compat-doc-fix' 2019-02-14 14:28:22 -08:00
git-receive-pack.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-reflog.txt reflog expire: cover reflog from all worktrees 2018-10-22 13:32:54 +09:00
git-remote-ext.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-remote-fd.txt Spelling fixes 2016-08-11 14:35:42 -07:00
git-remote-helpers.txto
git-remote-testgit.txt
git-remote.txt Merge branch 'nd/remote-update-doc' 2018-06-04 21:39:49 +09:00
git-repack.txt Merge branch 'cc/delta-islands' 2018-09-17 13:53:55 -07:00
git-replace.txt replace: introduce --convert-graft-file 2018-04-30 11:12:30 +09:00
git-request-pull.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-rerere.txt rerere: add note about files with existing conflict markers 2018-08-29 09:03:29 -07:00
git-reset.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-rev-list.txt rev-list: add list-objects filtering support 2017-11-22 14:11:57 +09:00
git-rev-parse.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-revert.txt doc: typeset long command-line options as literal 2016-06-28 08:36:45 -07:00
git-rm.txt treewide: correct several "up-to-date" to "up to date" 2017-08-23 12:17:22 -07:00
git-send-email.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-send-pack.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-sh-i18n--envsubst.txt
git-sh-i18n.txt
git-sh-setup.txt doc: more consistency in environment variables format 2016-06-08 12:04:37 -07:00
git-shell.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-shortlog.txt git-[short]log.txt: unify quoted standalone -- 2018-04-18 12:49:26 +09:00
git-show-branch.txt doc: fix small typo in git show-branch 2018-10-18 12:26:51 +09:00
git-show-index.txt show-index: update documentation for index v2 2018-05-29 00:28:22 +09:00
git-show-ref.txt git-show-ref.txt: fix order of flags 2019-01-10 10:29:05 -08:00
git-show.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-stage.txt Documentation: adjust document title underlining 2014-10-13 13:35:18 -07:00
git-stash.txt git-stash.txt: remove extra square bracket 2018-03-27 19:09:13 -07:00
git-status.txt git-status.txt: render tables correctly under Asciidoctor 2018-12-26 15:29:30 -08:00
git-stripspace.txt usage: do not insist that standard input must come from a file 2015-10-16 15:27:52 -07:00
git-submodule.txt Merge branch 'pc/submodule-helper-foreach' 2018-06-25 13:22:35 -07:00
git-svn.txt Documentation: spelling and grammar fixes 2018-06-22 14:26:23 -07:00
git-symbolic-ref.txt
git-tag.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-tools.txt doc: replace or.cz gitwiki link with git.wiki.kernel.org 2017-04-20 22:05:37 -07:00
git-unpack-file.txt
git-unpack-objects.txt unpack-objects: add --max-input-size=<size> option 2016-08-24 12:31:05 -07:00
git-update-index.txt Merge branch 'jc/update-index-doc' 2018-08-20 11:33:50 -07:00
git-update-ref.txt Merge branch 'ah/doc-updates' into maint 2018-11-21 22:58:07 +09:00
git-update-server-info.txt
git-upload-archive.txt Documentation: match underline with the text 2015-10-22 10:16:12 -07:00
git-upload-pack.txt doc: tidy asciidoc style 2019-01-23 11:37:29 -08:00
git-var.txt doc: keep first level section header in upper case 2018-05-02 17:03:33 +09:00
git-verify-commit.txt Merge branch 'dn/gpg-doc' into maint 2016-07-06 13:06:36 -07:00
git-verify-pack.txt git-verify-pack.txt: fix inconsistent spelling of "packfile" 2015-05-17 11:24:57 -07:00
git-verify-tag.txt builtin/verify-tag: add --format to verify-tag 2017-01-17 16:10:22 -08:00
git-web--browse.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
git-whatchanged.txt
git-worktree.txt Merge branch 'nd/per-worktree-ref-iteration' 2018-11-13 22:37:26 +09:00
git-write-tree.txt
git.txt Merge branch 'ah/doc-updates' into maint 2018-11-21 22:58:07 +09:00
gitattributes.txt Merge branch 'jk/autocrlf-overrides-eol-doc' 2019-02-06 22:05:23 -08:00
gitcli.txt Use proper syntax for replaceables in command docs 2018-05-25 17:16:47 +09:00
gitcore-tutorial.txt treewide: correct several "up-to-date" to "up to date" 2017-08-23 12:17:22 -07:00
gitcredentials.txt doc: clarify gitcredentials path component matching 2018-09-27 15:24:50 -07:00
gitcvs-migration.txt Merge branch 'sb/doc-unify-bottom' 2017-02-15 12:54:20 -08:00
gitdiffcore.txt log -G: ignore binary files 2018-12-26 14:59:37 -08:00
giteveryday.txt Documentation: spelling and grammar fixes 2018-06-22 14:26:23 -07:00
gitglossary.txt Documentation: unify bottom "part of git suite" lines 2017-02-09 15:14:01 -08:00
githooks.txt git-p4: add the p4-pre-submit hook 2018-08-01 13:37:18 -07:00
gitignore.txt Merge branch 'nd/wildmatch-double-asterisk' 2018-11-13 22:37:19 +09:00
gitk.txt doc: convert [\--] to [--] 2018-04-18 12:49:26 +09:00
gitmodules.txt doc: fix inappropriate monospace formatting 2018-10-23 12:23:09 +09:00
gitnamespaces.txt doc: mention transfer data leaks in more places 2016-11-14 11:23:07 -08:00
gitremote-helpers.txt Merge branch 'bw/protocol-v2' 2018-05-08 15:59:16 +09:00
gitrepository-layout.txt doc: move extensions.worktreeConfig to the right place 2018-11-16 14:10:31 +09:00
gitrevisions.txt push doc: correct lies about how push refspecs work 2018-08-31 14:04:06 -07:00
gitsubmodules.txt doc: fix inappropriate monospace formatting 2018-10-23 12:23:09 +09:00
gittutorial-2.txt Documentation: unify bottom "part of git suite" lines 2017-02-09 15:14:01 -08:00
gittutorial.txt treewide: correct several "up-to-date" to "up to date" 2017-08-23 12:17:22 -07:00
gitweb.conf.txt Merge branch 'do/gitweb-strict-export-conf-doc' 2019-01-14 15:29:33 -08:00
gitweb.txt doc: use https links to Wikipedia to avoid http redirects 2017-05-15 13:04:54 +09:00
gitworkflows.txt Merge branch 'km/doc-workflows-typofix' 2018-06-18 10:18:42 -07:00
glossary-content.txt tree-walk: support :(attr) matching 2018-11-19 10:50:33 +09:00
howto-index.sh howto-index.sh: use the $( ... ) construct for command substitution 2014-04-17 11:14:57 -07:00
i18n.txt doc: camelCase the i18n config variables to improve readability 2017-07-17 15:11:26 -07:00
install-doc-quick.sh install-doc-quick: allow specifying what ref to install 2017-12-12 16:49:40 -08:00
install-webdoc.sh install-webdoc.sh: use the $( ... ) construct for command substitution 2014-04-17 11:14:58 -07:00
line-range-format.txt Documentation: change -L:<regex> to -L:<funcname> 2015-04-20 11:05:50 -07:00
lint-gitlink.perl ci: validate "linkgit:" in documentation 2016-05-10 11:15:04 -07:00
mailmap.txt
Makefile Documentation/Makefile add optional targets for l10n 2019-01-07 13:05:36 -08:00
manpage-1.72.xsl
manpage-base-url.xsl.in
manpage-base.xsl
manpage-bold-literal.xsl
manpage-normal.xsl
manpage-quote-apos.xsl
manpage-suppress-sp.xsl
merge-options.txt merge: allow fast-forward when merging a tracked tag 2018-02-16 11:22:43 -08:00
merge-strategies.txt merge: add merge.renames config setting 2018-05-08 16:19:41 +09:00
pretty-formats.txt Merge branch 'kl/pretty-doc-markup-fix' 2019-02-08 20:44:53 -08:00
pretty-options.txt Merge branch 'tr/doc-tt' into maint 2016-07-06 13:06:34 -07:00
pull-fetch-param.txt fetch doc: correct grammar in --force docs 2018-09-20 09:40:03 -07:00
rev-list-options.txt Merge branch 'lt/date-human' 2019-02-06 22:05:24 -08:00
revisions.txt Merge branch 'wc/find-commit-with-pattern-on-detached-head' 2018-07-24 14:50:49 -07:00
sequencer.txt
SubmittingPatches SubmittingPatches: mention doc-diff 2018-08-21 12:54:33 -07:00
texi.xsl Documentation: add XSLT to fix DocBook for Texinfo 2017-01-23 10:56:53 -08:00
transfer-data-leaks.txt doc: mention transfer data leaks in more places 2016-11-14 11:23:07 -08:00
urls-remotes.txt Documentation: match underline with the text 2015-10-22 10:16:12 -07:00
urls.txt transport: drop support for git-over-rsync 2016-02-01 13:07:41 -08:00
user-manual.conf
user-manual.txt checkout: describe_detached_head: remove ellipsis after committish 2017-12-06 07:32:40 -08:00