Custom compression levels for objects and packs
[git/git.git] / Documentation / git-pack-objects.txt
1 git-pack-objects(1)
2 ===================
3
4 NAME
5 ----
6 git-pack-objects - Create a packed archive of objects
7
8
9 SYNOPSIS
10 --------
11 [verse]
12 'git-pack-objects' [-q] [--no-reuse-delta] [--delta-base-offset] [--non-empty]
13 [--local] [--incremental] [--window=N] [--depth=N] [--all-progress]
14 [--revs [--unpacked | --all]*] [--stdout | base-name] < object-list
15
16
17 DESCRIPTION
18 -----------
19 Reads list of objects from the standard input, and writes a packed
20 archive with specified base-name, or to the standard output.
21
22 A packed archive is an efficient way to transfer set of objects
23 between two repositories, and also is an archival format which
24 is efficient to access. The packed archive format (.pack) is
25 designed to be unpackable without having anything else, but for
26 random access, accompanied with the pack index file (.idx).
27
28 'git-unpack-objects' command can read the packed archive and
29 expand the objects contained in the pack into "one-file
30 one-object" format; this is typically done by the smart-pull
31 commands when a pack is created on-the-fly for efficient network
32 transport by their peers.
33
34 Placing both in the pack/ subdirectory of $GIT_OBJECT_DIRECTORY (or
35 any of the directories on $GIT_ALTERNATE_OBJECT_DIRECTORIES)
36 enables git to read from such an archive.
37
38 In a packed archive, an object is either stored as a compressed
39 whole, or as a difference from some other object. The latter is
40 often called a delta.
41
42
43 OPTIONS
44 -------
45 base-name::
46 Write into a pair of files (.pack and .idx), using
47 <base-name> to determine the name of the created file.
48 When this option is used, the two files are written in
49 <base-name>-<SHA1>.{pack,idx} files. <SHA1> is a hash
50 of the sorted object names to make the resulting filename
51 based on the pack content, and written to the standard
52 output of the command.
53
54 --stdout::
55 Write the pack contents (what would have been written to
56 .pack file) out to the standard output.
57
58 --revs::
59 Read the revision arguments from the standard input, instead of
60 individual object names. The revision arguments are processed
61 the same way as gitlink:git-rev-list[1] with `--objects` flag
62 uses its `commit` arguments to build the list of objects it
63 outputs. The objects on the resulting list are packed.
64
65 --unpacked::
66 This implies `--revs`. When processing the list of
67 revision arguments read from the standard input, limit
68 the objects packed to those that are not already packed.
69
70 --all::
71 This implies `--revs`. In addition to the list of
72 revision arguments read from the standard input, pretend
73 as if all refs under `$GIT_DIR/refs` are specified to be
74 included.
75
76 --window=[N], --depth=[N]::
77 These two options affect how the objects contained in
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.
86 The default value for --window is 10 and --depth is 50.
87
88 --incremental::
89 This flag causes an object already in a pack ignored
90 even if it appears in the standard input.
91
92 --local::
93 This flag is similar to `--incremental`; instead of
94 ignoring all packed objects, it only ignores objects
95 that are packed and not in the local object store
96 (i.e. borrowed from an alternate).
97
98 --non-empty::
99 Only create a packed archive if it would contain at
100 least one object.
101
102 --progress::
103 Progress status is reported on the standard error stream
104 by default when it is attached to a terminal, unless -q
105 is specified. This flag forces progress status even if
106 the standard error stream is not directed to a terminal.
107
108 --all-progress::
109 When --stdout is specified then progress report is
110 displayed during the object count and deltification phases
111 but inhibited during the write-out phase. The reason is
112 that in some cases the output stream is directly linked
113 to another command which may wish to display progress
114 status of its own as it processes incoming pack data.
115 This flag is like --progress except that it forces progress
116 report for the write-out phase as well even if --stdout is
117 used.
118
119 -q::
120 This flag makes the command not to report its progress
121 on the standard error stream.
122
123 --no-reuse-delta::
124 When creating a packed archive in a repository that
125 has existing packs, the command reuses existing deltas.
126 This sometimes results in a slightly suboptimal pack.
127 This flag tells the command not to reuse existing deltas
128 but compute them from scratch.
129
130 --no-reuse-object::
131 This flag tells the command not to reuse existing object data at all,
132 including non deltified object, forcing recompression of everything.
133 This implies --no-reuse-delta. Useful only in the obscure case where
134 wholesale enforcement of a different compression level on the
135 packed data is desired.
136
137 --compression=[N]::
138 Specifies compression level for newly-compressed data in the
139 generated pack. If not specified, pack compression level is
140 determined first by pack.compression, then by core.compression,
141 and defaults to -1, the zlib default, if neither is set.
142 Data copied from loose objects will be recompressed
143 if core.legacyheaders was true when they were created or if
144 the loose compression level (see core.loosecompression and
145 core.compression) is now a different value than the pack
146 compression level. Add --no-reuse-object if you want to force
147 a uniform compression level on all data no matter the source.
148
149 --delta-base-offset::
150 A packed archive can express base object of a delta as
151 either 20-byte object name or as an offset in the
152 stream, but older version of git does not understand the
153 latter. By default, git-pack-objects only uses the
154 former format for better compatibility. This option
155 allows the command to use the latter format for
156 compactness. Depending on the average delta chain
157 length, this option typically shrinks the resulting
158 packfile by 3-5 per-cent.
159
160 --index-version=<version>[,<offset>]::
161 This is intended to be used by the test suite only. It allows
162 to force the version for the generated pack index, and to force
163 64-bit index entries on objects located above the given offset.
164
165
166 Author
167 ------
168 Written by Linus Torvalds <torvalds@osdl.org>
169
170 Documentation
171 -------------
172 Documentation by Junio C Hamano
173
174 See Also
175 --------
176 gitlink:git-rev-list[1]
177 gitlink:git-repack[1]
178 gitlink:git-prune-packed[1]
179
180 GIT
181 ---
182 Part of the gitlink:git[7] suite
183