Mercurial > hg
comparison mercurial/help/internals/requirements.txt @ 28523:045fe7042510
help: document requirements
We didn't have unified documentation of the various repository
requirements. This patch changes that.
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Sat, 12 Mar 2016 18:51:07 -0800 |
parents | |
children | aba2bb2a6d0f |
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1 Requirements | |
2 ============ | |
3 | |
4 Repositories contain a file (``.hg/requires``) containing a list of | |
5 features/capabilities that are *required* for clients to interface | |
6 with the repository. This file has been present in Mercurial since | |
7 version 0.9.2 (released December 2006). | |
8 | |
9 One of the first things clients do when opening a repository is read | |
10 ``.hg/requires`` and verify that all listed requirements are supported, | |
11 aborting if not. Requirements are therefore a strong mechanism to | |
12 prevent incompatible clients from reading from unknown repository | |
13 formats or even corrupting them by writing to them. | |
14 | |
15 Extensions may add requirements. When they do this, clients not running | |
16 an extension will be unable to read from repositories. | |
17 | |
18 The following sections describe the requirements defined by the | |
19 Mercurial core distribution. | |
20 | |
21 revlogv1 | |
22 -------- | |
23 | |
24 When present, revlogs are version 1 (RevlogNG). RevlogNG was introduced | |
25 in 2006. The ``revlogv1`` requirement has been enabled by default | |
26 since the ``requires`` file was introduced in Mercurial 0.9.2. | |
27 | |
28 If this requirement is not present, version 0 revlogs are assumed. | |
29 | |
30 store | |
31 ----- | |
32 | |
33 The *store* repository layout should be used. | |
34 | |
35 This requirement has been enabled by default since the ``requires`` file | |
36 was introduced in Mercurial 0.9.2. | |
37 | |
38 fncache | |
39 ------- | |
40 | |
41 The *fncache* repository layout should be used. | |
42 | |
43 The *fncache* layout hash encodes filenames with long paths and | |
44 encodes reserved filenames. | |
45 | |
46 This requirement is enabled by default when the *store* requirement is | |
47 enabled (which is the default behavior). It was introduced in Mercurial | |
48 1.1 (released December 2008). | |
49 | |
50 shared | |
51 ------ | |
52 | |
53 Denotes that the store for a repository is shared from another location | |
54 (defined by the ``.hg/sharedpath`` file). | |
55 | |
56 This requirement is set when a repository is created via :hg:`share`. | |
57 | |
58 The requirement was added in Mercurial 1.3 (released July 2009). | |
59 | |
60 dotencode | |
61 --------- | |
62 | |
63 The *dotencode* repository layout should be used. | |
64 | |
65 The *dotencode* layout encodes the first period or space in filenames | |
66 to prevent issues on OS X and Windows. | |
67 | |
68 This requirement is enabled by default when the *store* requirement | |
69 is enabled (which is the default behavior). It was introduced in | |
70 Mercurial 1.7 (released November 2010). | |
71 | |
72 parentdelta | |
73 ----------- | |
74 | |
75 Denotes a revlog delta encoding format that was experimental and | |
76 replaced by *generaldelta*. It should not be seen in the wild because | |
77 it was never enabled by default. | |
78 | |
79 This requirement was added in Mercurial 1.7 and removed in Mercurial | |
80 1.9. | |
81 | |
82 generaldelta | |
83 ------------ | |
84 | |
85 Revlogs should be created with the *generaldelta* flag enabled. The | |
86 generaldelta flag will cause deltas to be encoded against a parent | |
87 revision instead of the previous revision in the revlog. | |
88 | |
89 Support for this requirement was added in Mercurial 1.9 (released | |
90 July 2011). The requirement was disabled on new repositories by | |
91 default until Mercurial 3.7 (released February 2016). | |
92 | |
93 manifestv2 | |
94 ---------- | |
95 | |
96 Denotes that version 2 of manifests are being used. | |
97 | |
98 Support for this requirement was added in Mercurial 3.4 (released | |
99 May 2015). The requirement is currently experimental and is disabled | |
100 by default. | |
101 | |
102 treemanifest | |
103 ------------ | |
104 | |
105 Denotes that tree manifests are being used. Tree manifests are | |
106 one manifest per directory (as opposed to a single flat manifest). | |
107 | |
108 Support for this requirement was added in Mercurial 3.4 (released | |
109 August 2015). The requirement is currently experimental and is | |
110 disabled by default. |