4
Preparing for data migration
5
----------------------------
7
Before starting a migration, there are a few important things to do
10
1. Take a complete backup.
12
2. Take some time to purge obsolete branches.
14
A complete backup gives you a safety net in case anything goes wrong.
16
Purging obsolete branches reduces the amount of data that needs to
17
be migrated. See `Finding obsolete branches`_ later for some tips
21
Introducing the upgrade-related commands
22
----------------------------------------
24
There are 3 important commands to be aware of when migrating data.
26
* **check** - check a repository, branch or tree for data integrity errors
28
* **reconcile** - fix data integrity errors
30
* **upgrade** - migrate data to a different format.
32
**reconcile** is rarely needed but it's good practice to run **check**
33
before and after running **upgrade**.
35
For detailed help on these commands, see the `Bazaar User Reference`_.
37
.. _Bazaar User Reference: ../user-reference/index.html
40
Communicating with your community
41
---------------------------------
43
To enable a smooth transition to the new format, you should:
45
1. Make one person responsible for migrating the trunk.
47
2. Test the migration of trunk works successfully.
49
3. Schedule a time for the trunk migration and notify your community
52
This advance warning should be long enough for users to have time
53
to upgrade Bazaar and any required plugins before the migration date.
55
For larger projects, allow some time for the migration itself.
56
You should have a good idea of how long the migration will take
57
after doing the test migration. It may make sense to do the migration
58
on a weekend or a Friday, giving yourself some breathing space if
61
After the trunk is migrated, you'll need to notify your community
62
accordingly, giving them instructions as to how to migrate their
63
local branches. Sample instructions are provided later in this
67
Migrating a standalone branch
68
-----------------------------
74
2. If there are errors, try using **bzr reconcile** to fix them.
75
If that fails, file a bug so we can help you resolve the issue
76
and get your trunk clean. If it works, take a backup copy of
79
2. Run **bzr upgrade --format** where *format* is 2a or later.
81
3. Run **bzr check** to confirm the final result is good.
84
Migrating branches in a shared repository
85
-----------------------------------------
87
Upgrade things in the following order:
89
1. Upgrade the shared repository.
90
2. Upgrade the branches.
91
3. Upgrade any lightweight checkouts.
93
As in the standalone branch case, be sure to run **check** before
94
and after the upgrade to check for any existing or introduced issues.
97
Migrating branches on Launchpad
98
-------------------------------
100
You have two options for upgrading your Launchpad branches. You can either
101
upgrade them remotely or you can upgrade them locally and push the migrated
102
branch to Launchpad. We recommend the latter. Upgrading remotely currently
103
requires a fast, rock solid network connection to the Launchpad servers, and
104
any interruption in that connection can leave you with a partially upgraded
105
branch. The instructions below are the safest and often fastest way to
106
upgrade your Launchpad branches.
108
To allow isolation between public and private branches, Launchpad
109
uses stacked branches rather than shared repositories as the core
110
technology for efficient branch storage. The process for migrating
111
to a new format for projects using Launchpad code hosting is therefore
112
different to migrating a personal or in-house project.
114
In Launchpad, a project can define a *development series* and associate a
115
branch with that series. The branch then becomes the *focus of development*
116
and gets special treatment and a shortcut URL. By default, if anybody
117
branches your project's focus of development and pushes changes back to
118
Launchpad, their branch will be stacked on your development focus branch.
119
Also, branches can be associated with other Launchpad artifacts such as bugs
120
and merge proposals. All of these things mean that upgrading your focus of
121
development branch is trickier.
123
Here are the steps to follow:
125
1. The nominated person grabs a copy of trunk and does the migration locally.
127
2. On Launchpad, unset the current trunk from being the development focus.
128
(This *must* be done or the following step won't work as expected.)
130
1. Go to your project's home page on Launchpad
132
2. Look for "XXX is the current focus of development"
134
3. Click on the edit (pencil) icon
136
4. Click on "Change details" in the portlet on the right
138
5. Scroll down to where it says "Branch: (Optional)"
140
6. Blank out this input field and click "Change"
142
3. Push the migrated trunk to Launchpad. See below if you want your
143
new migrated development focus branch to have the same name as your old
144
pre-migration development focus branch.
146
4. Set it as the development focus. Follow the instructions above but at step
147
5, enter the name of the newly migrated branch you just pushed.
149
5. Ask users subscribed to the old trunk to subscribe to the new one.
151
In summary, these steps mean that the old trunk is still available and
152
existing branches stacked on it will continue to be so. However, the
153
development focus has switched to the migrated trunk and any new branches
154
pushed to Launchpad for your project will now stack on it.
156
You are now ready to tell your community that the new trunk is available
157
and to give them instructions on migrating any local branches they have.
159
If you want your new migrated development focus branch to have the same name
160
as your old pre-migration branch, you need to do a few extra things before you
161
establish the new development focus.
163
1. Rename your old pre-migration branch; use something like
164
**foo-obsolete-do-not-use**. You will really not want to delete this
165
because there will be artifacts (bugs, merge proposals, etc.) associated
168
2. Rename the new migrated branch to the pre-migration branch's old name.
170
3. Re-establish the development focus branch using the new migrated branch's
171
new name (i.e. the old pre-migration branch's original name).
174
Migrating local branches after a central trunk has migrated
175
-----------------------------------------------------------
177
To migrate a standalone branch:
179
1. Grab the latest branch from the central location into a
182
2. Pull or merge any changes you've made in your existing branch
185
To migrate branches in a shared repository:
187
1. Create a fresh shared repository in the new format (2a or later).
189
2. Grab the latest branch from the central location into a
190
new directory inside the shared repository.
192
3. Decide which of your local branches you want to migrate. (If you
193
haven't already, now's a good time for `Finding obsolete branches`_
194
and purging them, after backing up first of course.)
196
4. To migrate each local branch of interest, there are 2 options:
198
* **init** an empty branch in the new repository and **pull** the
199
revisions from the branch in the old repository across.
201
* In the new repository, **branch** from trunk to the new branch
202
name then **merge** your changes from the matching branch in the
205
The first method will give you a branch which is identical (in terms of
206
revision history) to the old branch, but it's parent branch will be set to the
207
old branch, not your new trunk. If you use this method, you'll probably update
208
the ``parent_location`` configuration variable in the ``branch.conf`` file
211
bzr config parent_location=XXX
213
``XXX`` being the URL to your new trunk.
215
In contrast, the second approach sets up the parent branch correctly.
216
However, it isn't ideal if you're not ready to include all the latest
217
revisions from trunk into that branch yet.
added
removed
doc/en/upgrade-guide/data_migration.txt
