Last modified by Thomas Mortagne on 2017/03/24

<
From version < 3.1 >
edited by Denis Gervalle
on 2012/12/20
To version < 4.1 >
edited by Denis Gervalle
on 2012/12/21
>
Change comment: Added some explanations about migration and potential issues

Summary

Details

Page properties
Content
... ... @@ -48,8 +48,22 @@
48 48  
49 49  == General Notes ==
50 50  
51 +{{warning}}
52 +PLEASE, BACKUP YOUR DATABASE BEFORE STARTING YOUR WIKI.
53 +AUTOMATED MIGRATION PROCEDURE TAKE PLACE AT STARTUP AND YOU MAY NEED TO START OVER IF YOU ENCOUNTER AN UNEXPECTED ISSUE.
54 +{{/warning}}
55 +
51 51  You may also want to [[import the default wiki XAR>>Main.Download]] in order to benefit from all the improvements listed above.
52 52  
53 53  {{warning}}
54 54  Always make sure you compare your ##xwiki.cfg## and ##xwiki.properties## files with the newest version since some configuration parameters were added. Note that you should add ##xwiki.store.migration=1## so that XWiki will attempt to automatically migrate your current database to the new schema. Make sure you backup your Database before doing anything.
55 55  {{/warning}}
61 +
62 +{{warning}}
63 +If you are migrating from an earlier version than 4.0, and your database contains statistics collected using a version earlier than 2.2, you will probably encounter an issue during our automated database migration. To avoid that issue, you will need to clean up your statistics by executing some SQL commands described in issue [[XWIKI-8129>>http://jira.xwiki.org/browse/XWIKI-8129]]. Be sure to apply these before attempting the migration. If your are in doubt, apply it, these could not hurt. If you don't, you will face duplicate IDs errors during the migration process, and it will fail, preventing you to run your wiki.
64 +{{/warning}}
65 +
66 +{{warning}}
67 +If you have encountered an issue with the migration, you may need to start over from a backup. Be careful that during the migration, two new tables have been created (in each xwiki database for a farm) and should be dropped when you restore a backup of a database coming from a version earlier than 4.x. These two tables are DATABASECHANGELOG and DATABASECHANGELOGLOCK. These should only be removed if you restore a pre-4.x database schema. Mixing an old database with these two tables will surely cause issue during schema updates (liquibase checksum failure).
68 +{{/warning}}
69 +

Get Connected