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In an environment where the multi-pack-index is useful, it is due to many pack-files and an inability to repack the object store into a single pack-file. However, it is likely that many of these pack-files are rather small, and could be repacked into a slightly larger pack-file without too much effort. It may also be important to ensure the object store is highly available and the repack operation does not interrupt concurrent git commands. Introduce a 'repack' subcommand to 'git multi-pack-index' that takes a '--batch-size' option. The subcommand will inspect the multi-pack-index for referenced pack-files whose size is smaller than the batch size, until collecting a list of pack-files whose sizes sum to larger than the batch size. Then, a new pack-file will be created containing the objects from those pack-files that are referenced by the multi-pack-index. The resulting pack is likely to actually be smaller than the batch size due to compression and the fact that there may be objects in the pack- files that have duplicate copies in other pack-files. The current change introduces the command-line arguments, and we add a test that ensures we parse these options properly. Since we specify a small batch size, we will guarantee that future implementations do not change the list of pack-files. In addition, we hard-code the modified times of the packs in the pack directory to ensure the list of packs sorted by modified time matches the order if sorted by size (ascending). This will be important in a future test. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
89 lines
2.6 KiB
Plaintext
89 lines
2.6 KiB
Plaintext
git-multi-pack-index(1)
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=======================
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NAME
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----
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git-multi-pack-index - Write and verify multi-pack-indexes
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SYNOPSIS
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--------
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[verse]
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'git multi-pack-index' [--object-dir=<dir>] <subcommand>
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DESCRIPTION
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-----------
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Write or verify a multi-pack-index (MIDX) file.
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OPTIONS
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-------
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--object-dir=<dir>::
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Use given directory for the location of Git objects. We check
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`<dir>/packs/multi-pack-index` for the current MIDX file, and
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`<dir>/packs` for the pack-files to index.
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The following subcommands are available:
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write::
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Write a new MIDX file.
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verify::
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Verify the contents of the MIDX file.
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expire::
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Delete the pack-files that are tracked by the MIDX file, but
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have no objects referenced by the MIDX. Rewrite the MIDX file
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afterward to remove all references to these pack-files.
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repack::
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Create a new pack-file containing objects in small pack-files
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referenced by the multi-pack-index. If the size given by the
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`--batch-size=<size>` argument is zero, then create a pack
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containing all objects referenced by the multi-pack-index. For
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a non-zero batch size, Select the pack-files by examining packs
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from oldest-to-newest, computing the "expected size" by counting
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the number of objects in the pack referenced by the
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multi-pack-index, then divide by the total number of objects in
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the pack and multiply by the pack size. We select packs with
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expected size below the batch size until the set of packs have
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total expected size at least the batch size. If the total size
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does not reach the batch size, then do nothing. If a new pack-
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file is created, rewrite the multi-pack-index to reference the
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new pack-file. A later run of 'git multi-pack-index expire' will
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delete the pack-files that were part of this batch.
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EXAMPLES
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--------
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* Write a MIDX file for the packfiles in the current .git folder.
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+
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-----------------------------------------------
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$ git multi-pack-index write
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-----------------------------------------------
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* Write a MIDX file for the packfiles in an alternate object store.
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+
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-----------------------------------------------
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$ git multi-pack-index --object-dir <alt> write
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-----------------------------------------------
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* Verify the MIDX file for the packfiles in the current .git folder.
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+
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-----------------------------------------------
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$ git multi-pack-index verify
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-----------------------------------------------
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SEE ALSO
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--------
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See link:technical/multi-pack-index.html[The Multi-Pack-Index Design
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Document] and link:technical/pack-format.html[The Multi-Pack-Index
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Format] for more information on the multi-pack-index feature.
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GIT
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---
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Part of the linkgit:git[1] suite
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