Difference between revisions of "Migrating mediawiki from mysql to sqlite"

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imported>ThorstenStaerk
(works as designed: https://www.mediawiki.org/wiki/Manual:User_table#user_options)
imported>ThorstenStaerk
(this error was the old one when the db was corrupted as well)
Line 36: Line 36:
 
== Error ==
 
== Error ==
 
When editing an article ''article'' I get the error message
 
When editing an article ''article'' I get the error message
−
  The revision #0 of the page named "''article''" does not exist.
+
  A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:
 +
    INSERT INTO phase3text (old_id,old_text,old_flags) VALUES (NULL,'= main.cpp =
 +
[...]
 +
from within function "Revision::insertOn/single-row". Database returned error "19: phase3text.old_id may not be NULL".
 +
The error happens in this code:
 +
$dbw->insert( 'text',
 +
array(
 +
'old_id'    => $old_id,
 +
'old_text' => $data,
 +
'old_flags' => $flags,
 +
), __METHOD__
 +
);
  
 
$old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );
 
$old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );

Revision as of 15:10, 10 September 2013

Overview

To migrate a mediawiki from MySQL to SQLite there are two basic approaches:

  • start with a new database and worry about
    • dumping all pages but the Main Page with the dumpBackup command and restoring them with the importDump command
    • keeping the articles' revisions
    • copying the Main Page from the old wiki to the new
    • copying the users and privileges from the old wiki to the new
    • copying the wiki statistics (like page visits) from the old wiki to the new
    • copying images and other files from the old wiki to the new
    • re-doing things like mediawiki extensions on the new wiki
    • re-doing your settings e.g. from LocalSettings.php on the new wiki
Matt gives a good overview about this
  • just migrate the database below your wiki

migrate database below your wiki

I wanted to migrate the database below my wiki so

  • I created a dump (aka backup aka export) of the database
mysqldump wikidb -u wikiuser -p > dump.sql
  • I got a MySQL -> SQLite converter
wget https://gist.github.com/esperlu/943776/raw/dd87f4088f6d5ec7563478f7a28a37ba02cf26e2/mysql2sqlite.sh
  • I started this converter to create a file /srv/www/htdocs/wikidb.sqlite:
sh mysql2sqlite.sh -u wikiuser -p wikidb | sqlite3 /srv/www/htdocs/wikidb.sqlite
  • change LocalSettings.php to reflect
$wgDBtype = "sqlite";
$wgDBserver = "";
$wgDBname = "wikidb";
$wgDBuser = "";
$wgDBpassword = "";
$wgSQLiteDataDir = "/srv/www/htdocs";
  • allow your webserver to write to the file:
chown wwwrun:www /srv/www/htdocs/wikidb.sqlite

I will admit that I still have some more things to explore here.

Error

When editing an article article I get the error message 

A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was:
   INSERT INTO phase3text (old_id,old_text,old_flags) VALUES (NULL,'= main.cpp = 
[...]
from within function "Revision::insertOn/single-row". Database returned error "19: phase3text.old_id may not be NULL".

The error happens in this code: $dbw->insert( 'text', array( 'old_id' => $old_id, 'old_text' => $data, 'old_flags' => $flags, ), __METHOD__ );

$old_id = $dbw->nextSequenceValue( 'text_old_id_seq' );

I guess it fails in line 1291 of includes/Revision.php

problem is 

SELECT  mr_blob,mr_resource,mr_timestamp  FROM phase3msg_resource  WHERE mr_resource IN ('user.options','user.tokens')  AND mr_lang = 'en'

more general: 

sqlite> select * from phase3msg_resource;
Error: database disk image is malformed

TroubleShooting

I got quite a lot of error messages that were easy to fix - provided you know how.

PDO exception

Symptom: When surfing to the wiki you get a page displaying this error message: 

Unexpected non-MediaWiki exception encountered, of type "PDOException"
exception 'PDOException' with message 'There is no active transaction' in /srv/www/htdocs/mediawiki/includes/db/DatabaseSqlite.php:664
Stack trace:

Solution: In LocalSettings.php set all occurrences of $wgDBuser to "". 

$wgDBuser = "";

Is not unique

Symptom: When calling mysql2sqlite.sh you get a lot of error messages like 

Error: near line 565: column cat_id is not unique
Error: near line 566: column cat_id is not unique

Solution: You cannot call mysql2sqlite.sh twice to the same target file. Delete the target file before you start the next conversion, like this: 

rm test.sqlite
sh /root/mysql2sqlite.sh -u wikiuser -p wikidb | sqlite3 test.sqlite

file is encrypted or not a database

Symptom: When trying to open the sqlite database on the command line you get the error message 

Unable to open database "../../data/my_wiki.sqlite": file is encrypted or is not a database

Solution: In my case I used the command sqlite to open the database. sqlite pointed to version 2 of sqlite. When I replaced the command sqlite by sqlite3 it worked: 

tweedleburg:/srv/www/htdocs/mediawiki # sqlite ../../data/my_wiki.sqlite 
Unable to open database "../../data/my_wiki.sqlite": file is encrypted or is not a database
tweedleburg:/srv/www/htdocs/mediawiki # sqlite3 ../../data/my_wiki.sqlite 
SQLite version 3.7.12.1 2012-05-22 02:45:53
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite>

See also

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