doc: mention bigFileThreshold for packing
PATCH 1/1 doc: mention bigFileThreshold for packing
From: Christian Walther <[email protected]>
Knowing about the core.bigFileThreshold configuration variable is helpful when examining pack file size differences between repositories. Add a reference to it to the manpages a user is likely to read in this situation.
---
doc: mention bigFileThreshold for packing
I recently spent a lot of time trying to figure out why git repack would create huge packs on some clones of my repository and small ones on others, until I found out about the existence of the core.bigFileThreshold configuration variable, which happened to be set on some and not on others. It would have saved me a lot of time if that variable had been mentioned in the relevant manpages that I was reading, git-repack and git-pack-objects. So this patch adds that.
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-872%2Fcwalther%2Fdeltadoc-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-872/cwalther/deltadoc-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/872
Documentation/git-pack-objects.txt | 4 ++++ Documentation/git-repack.txt | 4 ++++ 2 files changed, 8 insertions(+)
Documentation/git-pack-objects.txt +4 -0
@@ -97,6 +97,10 @@ base-name:: side, because delta data needs to be applied that many times to get to the necessary object. + +Note that delta compression is never used on objects larger than the +`core.bigFileThreshold` configuration variable (see +linkgit:git-config[1]). ++ The default value for --window is 10 and --depth is 50. The maximum depth is 4095.
Documentation/git-repack.txt +4 -0
@@ -96,6 +96,10 @@ to the new separate pack will be written. affects the performance on the unpacker side, because delta data needs to be applied that many times to get to the necessary object. + +Note that delta compression is never used on objects larger than the +`core.bigFileThreshold` configuration variable (see +linkgit:git-config[1]). ++ The default value for --window is 10 and --depth is 50. The maximum depth is 4095.
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"Christian Walther via GitGitGadget" <[email protected]>
Quoted 6 lines · writes:
From: Christian Walther <[email protected]>
Knowing about the core.bigFileThreshold configuration variable is helpful when examining pack file size differences between repositories. Add a reference to it to the manpages a user is likely to read in this situation.
Thanks.
I doubt that the description of --window/--depth command line options, for both repack and pack-objects, is the best place to add this "Note". Even if we were to add it as an appendix to these places, please do not break the flow of explanation by inserting it before the description of the default values of these options.
Quoted 7 lines
I recently spent a lot of time trying to figure out why git repack would create huge packs on some clones of my repository and small ones on others, until I found out about the existence of the core.bigFileThreshold configuration variable, which happened to be set on some and not on others. It would have saved me a lot of time if that variable had been mentioned in the relevant manpages that I was reading, git-repack and git-pack-objects. So this patch adds that.
Not related to the contents of the patch, but I am somewhat curious to know what configuration resulted in the "huge" ones and "small" ones. Documentation/config/core.txt::core.bigFileThreashold may be helped by addition of a success story, and the configuration for the "small" ones may be a good place to start.
Thanks
Quoted 5 lines · Junio C Hamano
I doubt that the description of --window/--depth command line options, for both repack and pack-objects, is the best place to add this "Note". Even if we were to add it as an appendix to these places, please do not break the flow of explanation by inserting it before the description of the default values of these options.
OK. That was where I would have looked for it, because it explains why --window wasn't effective in my attempts to get better compression, but I don't insist on it - any place would have worked, as I read both manpages back and forth several times.
In git-repack.txt, there is a "Configuration" section at the bottom, I guess it would fit there? There is none in git-pack-objects.txt, but I could add it. What do you think?
Quoted 9 lines
Quoted 3 lines
I recently spent a lot of time trying to figure out why git repack would create huge packs on some clones of my repository and small ones on others
Not related to the contents of the patch, but I am somewhat curious to know what configuration resulted in the "huge" ones and "small" ones. Documentation/config/core.txt::core.bigFileThreashold may be helped by addition of a success story, and the configuration for the "small" ones may be a good place to start.
The "huge" repository had bigFileThreshold = 1m. That was set by SubGit when converting from Subversion, for reasons unknown to me (see some discussion at https://support.tmatesoft.com/t/reduce-repository-size/2551 and https://issues.tmatesoft.com/issue/SGT-604). The result is a pack file of about 3 GB.
The "small" repository has it unset, so the default 512m applies, resulting in a pack file of about 50 MB.
What causes the huge difference is that the repository contains a "changelog" file that changes in almost every commit and has grown to 2.4 MB over 10000 commits. So it exists in about that many different versions, of which about 6000 are larger than 1 MB, but they only differ from each other by successive addition of small pieces.
I'm not sure if that makes for a good success story. 1m seems a rather extreme value to me. If you think so, I can try to come up with something.
Thanks
Christian
Quoted 8 lines · Christian Walther
Quoted 5 lines · Junio C Hamano
I doubt that the description of --window/--depth command line options, for both repack and pack-objects, is the best place to add this "Note". Even if we were to add it as an appendix to these places, please do not break the flow of explanation by inserting it before the description of the default values of these options.
Quoted 4 lines
OK. That was where I would have looked for it, because it explains why --window wasn't effective in my attempts to get better compression, but I don't insist on it - any place would have worked, as I read both manpages back and forth several times.
The "pack-objects" command (and to some degree "repack", too) is about packing throughout, and --depth/--window is not necessarily the central piece of the puzzle, and that, together with disruption of the flow of the original explanation, was the reason why I found the initial location a bit odd.
Quoted 3 lines
In git-repack.txt, there is a "Configuration" section at the bottom, I guess it would fit there? There is none in git-pack-objects.txt, but I could add it. What do you think?
You're right---if there is an existing CONFIGURATION section, that may be a much better place. There are configuration variables that affect how the packing works other than the core.bigFileThreshold, and attributes like "delta" would also affect the outcome.
Describing all in one CONFIGURATION section would be valuable.
What I queued is with the following ready to be squashed in, primarily because I was lazy and didn't have time/inclination to look for a better place myself ;-)
Thanks.
---- >8 ----
Subject: [PATCH] fixup! doc: mention bigFileThreshold for packing
--- Documentation/git-pack-objects.txt | 7 +++---- Documentation/git-repack.txt | 7 +++---- 2 files changed, 6 insertions(+), 8 deletions(-)
Documentation/git-pack-objects.txt +3 -4
@@ -97,12 +97,11 @@ base-name:: side, because delta data needs to be applied that many times to get to the necessary object. + -Note that delta compression is never used on objects larger than the -`core.bigFileThreshold` configuration variable (see -linkgit:git-config[1]). -+ The default value for --window is 10 and --depth is 50. The maximum depth is 4095. ++ +Note that delta compression is never used on objects larger than the +`core.bigFileThreshold` configuration variable (see linkgit:git-config[1]). --window-memory=<n>:: This option provides an additional limit on top of `--window`;
Documentation/git-repack.txt +3 -4
@@ -96,12 +96,11 @@ to the new separate pack will be written. affects the performance on the unpacker side, because delta data needs to be applied that many times to get to the necessary object. + -Note that delta compression is never used on objects larger than the -`core.bigFileThreshold` configuration variable (see -linkgit:git-config[1]). -+ The default value for --window is 10 and --depth is 50. The maximum depth is 4095. ++ +Note that delta compression is never used on objects larger than the +`core.bigFileThreshold` configuration variable (see linkgit:git-config[1]). --threads=<n>:: This option is passed through to `git pack-objects`.
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PATCH v2 1/1 doc: mention bigFileThreshold for packing
In reply to Christian Walther via GitGitGadgetFrom: Christian Walther <[email protected]>
Knowing about the core.bigFileThreshold configuration variable is helpful when examining pack file size differences between repositories. Add a reference to it to the manpages a user is likely to read in this situation.
Capitalize CONFIGURATION for consistency with other pages having such a section.
---
doc: mention bigFileThreshold for packing
I recently spent a lot of time trying to figure out why git repack would create huge packs on some clones of my repository and small ones on others, until I found out about the existence of the core.bigFileThreshold configuration variable, which happened to be set on some and not on others. It would have saved me a lot of time if that variable had been mentioned in the relevant manpages that I was reading, git-repack and git-pack-objects. So this patch adds that.
Changes in v2:
* Move additions to the CONFIGURATION section at the bottom.
* Reword a little after realizing that there are more configuration variables affecting packing.
* Capitalize CONFIGURATION for consistency with other pages having such a section.
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-872%2Fcwalther%2Fdeltadoc-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-872/cwalther/deltadoc-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/872
Range-diff vs v1:
1: 20b9a56d94b7 < -: ------------ doc: mention bigFileThreshold for packing -: ------------ > 1: 027d1038fbb1 doc: mention bigFileThreshold for packing
Documentation/git-pack-objects.txt | 11 +++++++++++ Documentation/git-repack.txt | 9 ++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)
Documentation/git-pack-objects.txt +11 -0
@@ -400,6 +400,17 @@ Note that we pick a single island for each regex to go into, using "last one wins" ordering (which allows repo-specific config to take precedence over user-wide config, and so forth). + +CONFIGURATION +------------- + +Various configuration variables affect packing, see +linkgit:git-config[1] (search for "pack" and "delta"). + +Notably, delta compression is not used on objects larger than the +`core.bigFileThreshold` configuration variable and on files with the +attribute `delta` set to false. + SEE ALSO -------- linkgit:git-rev-list[1]
Documentation/git-repack.txt +8 -1
@@ -165,9 +165,12 @@ depth is 4095. Pass the `--delta-islands` option to `git-pack-objects`, see linkgit:git-pack-objects[1]. -Configuration +CONFIGURATION ------------- +Various configuration variables affect packing, see +linkgit:git-config[1] (search for "pack" and "delta"). + By default, the command passes `--delta-base-offset` option to 'git pack-objects'; this typically results in slightly smaller packs, but the generated packs are incompatible with versions of Git older than
@@ -178,6 +181,10 @@ need to set the configuration variable `repack.UseDeltaBaseOffset` to is unaffected by this option as the conversion is performed on the fly as needed in that case. +Delta compression is not used on objects larger than the +`core.bigFileThreshold` configuration variable and on files with the +attribute `delta` set to false. + SEE ALSO -------- linkgit:git-pack-objects[1]
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