threaded delta search: better chunck split point
[git/git.git] / Documentation / git-pack-objects.txt
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1git-pack-objects(1)
2===================
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3
4NAME
5----
7bd7f280 6git-pack-objects - Create a packed archive of objects
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7
8
9SYNOPSIS
10--------
ca5381d4 11[verse]
63fba759 12'git-pack-objects' [-q] [--no-reuse-delta] [--delta-base-offset] [--non-empty]
fa438a2e 13 [--local] [--incremental] [--window=N] [--depth=N] [--all-progress]
4321134c 14 [--revs [--unpacked | --all]*] [--stdout | base-name] < object-list
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15
16
17DESCRIPTION
18-----------
19Reads list of objects from the standard input, and writes a packed
20archive with specified base-name, or to the standard output.
21
22A packed archive is an efficient way to transfer set of objects
23between two repositories, and also is an archival format which
24is efficient to access. The packed archive format (.pack) is
25designed to be unpackable without having anything else, but for
26random access, accompanied with the pack index file (.idx).
27
28'git-unpack-objects' command can read the packed archive and
29expand the objects contained in the pack into "one-file
30one-object" format; this is typically done by the smart-pull
31commands when a pack is created on-the-fly for efficient network
32transport by their peers.
33
2c6e4771 34Placing both in the pack/ subdirectory of $GIT_OBJECT_DIRECTORY (or
5f40520f 35any of the directories on $GIT_ALTERNATE_OBJECT_DIRECTORIES)
72e9340c 36enables git to read from such an archive.
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38In a packed archive, an object is either stored as a compressed
39whole, or as a difference from some other object. The latter is
40often called a delta.
41
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42
43OPTIONS
44-------
45base-name::
46 Write into a pair of files (.pack and .idx), using
47 <base-name> to determine the name of the created file.
48 When this option is used, the two files are written in
49 <base-name>-<SHA1>.{pack,idx} files. <SHA1> is a hash
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50 of the sorted object names to make the resulting filename
51 based on the pack content, and written to the standard
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52 output of the command.
53
54--stdout::
89438677 55 Write the pack contents (what would have been written to
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56 .pack file) out to the standard output.
57
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58--revs::
59 Read the revision arguments from the standard input, instead of
60 individual object names. The revision arguments are processed
61 the same way as gitlink:git-rev-list[1] with `--objects` flag
62 uses its `commit` arguments to build the list of objects it
63 outputs. The objects on the resulting list are packed.
64
65--unpacked::
66 This implies `--revs`. When processing the list of
67 revision arguments read from the standard input, limit
68 the objects packed to those that are not already packed.
69
70--all::
71 This implies `--revs`. In addition to the list of
72 revision arguments read from the standard input, pretend
3df19671 73 as if all refs under `$GIT_DIR/refs` are specified to be
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74 included.
75
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76--window=[N], --depth=[N]::
77 These two options affect how the objects contained in
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78 the pack are stored using delta compression. The
79 objects are first internally sorted by type, size and
80 optionally names and compared against the other objects
81 within --window to see if using delta compression saves
82 space. --depth limits the maximum delta depth; making
83 it too deep affects the performance on the unpacker
84 side, because delta data needs to be applied that many
85 times to get to the necessary object.
618e613a 86 The default value for --window is 10 and --depth is 50.
5f40520f 87
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88--window-memory=[N]::
89 This option provides an additional limit on top of `--window`;
90 the window size will dynamically scale down so as to not take
91 up more than N bytes in memory. This is useful in
92 repositories with a mix of large and small objects to not run
93 out of memory with a large window, but still be able to take
94 advantage of the large window for the smaller objects. The
95 size can be suffixed with "k", "m", or "g".
96 `--window-memory=0` makes memory usage unlimited, which is the
97 default.
98
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99--max-pack-size=<n>::
100 Maximum size of each output packfile, expressed in MiB.
101 If specified, multiple packfiles may be created.
102 The default is unlimited.
103
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104--incremental::
105 This flag causes an object already in a pack ignored
106 even if it appears in the standard input.
107
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108--local::
109 This flag is similar to `--incremental`; instead of
110 ignoring all packed objects, it only ignores objects
111 that are packed and not in the local object store
112 (i.e. borrowed from an alternate).
5f40520f 113
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114--non-empty::
115 Only create a packed archive if it would contain at
116 least one object.
117
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118--progress::
119 Progress status is reported on the standard error stream
120 by default when it is attached to a terminal, unless -q
121 is specified. This flag forces progress status even if
122 the standard error stream is not directed to a terminal.
123
124--all-progress::
125 When --stdout is specified then progress report is
126 displayed during the object count and deltification phases
127 but inhibited during the write-out phase. The reason is
128 that in some cases the output stream is directly linked
129 to another command which may wish to display progress
130 status of its own as it processes incoming pack data.
131 This flag is like --progress except that it forces progress
132 report for the write-out phase as well even if --stdout is
133 used.
134
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135-q::
136 This flag makes the command not to report its progress
137 on the standard error stream.
138
139--no-reuse-delta::
140 When creating a packed archive in a repository that
141 has existing packs, the command reuses existing deltas.
142 This sometimes results in a slightly suboptimal pack.
143 This flag tells the command not to reuse existing deltas
144 but compute them from scratch.
145
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146--no-reuse-object::
147 This flag tells the command not to reuse existing object data at all,
148 including non deltified object, forcing recompression of everything.
960ccca6 149 This implies --no-reuse-delta. Useful only in the obscure case where
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150 wholesale enforcement of a different compression level on the
151 packed data is desired.
152
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153--compression=[N]::
154 Specifies compression level for newly-compressed data in the
155 generated pack. If not specified, pack compression level is
156 determined first by pack.compression, then by core.compression,
157 and defaults to -1, the zlib default, if neither is set.
158 Data copied from loose objects will be recompressed
159 if core.legacyheaders was true when they were created or if
160 the loose compression level (see core.loosecompression and
161 core.compression) is now a different value than the pack
162 compression level. Add --no-reuse-object if you want to force
163 a uniform compression level on all data no matter the source.
164
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165--delta-base-offset::
166 A packed archive can express base object of a delta as
167 either 20-byte object name or as an offset in the
168 stream, but older version of git does not understand the
169 latter. By default, git-pack-objects only uses the
170 former format for better compatibility. This option
171 allows the command to use the latter format for
172 compactness. Depending on the average delta chain
173 length, this option typically shrinks the resulting
174 packfile by 3-5 per-cent.
175
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176--index-version=<version>[,<offset>]::
177 This is intended to be used by the test suite only. It allows
178 to force the version for the generated pack index, and to force
179 64-bit index entries on objects located above the given offset.
180
ca5381d4 181
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182Author
183------
184Written by Linus Torvalds <torvalds@osdl.org>
185
186Documentation
187-------------
188Documentation by Junio C Hamano
189
46444f51 190See Also
e31bb3bb 191--------
4321134c 192gitlink:git-rev-list[1]
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193gitlink:git-repack[1]
194gitlink:git-prune-packed[1]
e31bb3bb 195
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196GIT
197---
a7154e91 198Part of the gitlink:git[7] suite