Wiki Farm Requirements
Reference
What a wiki farm requires is decided by its DBMS and by the privileges XWiki holds on it.
Supported Databases
Check the supported databases for XWiki.
| Database | Each wiki of the farm is | Notes |
|---|---|---|
| MySQL | A separate database | Created with the character set and the collation of the main wiki's database |
| MariaDB | A separate database | XWiki recognises MariaDB as MySQL, so the two behave identically |
| Oracle | A separate Oracle user, which owns a schema of the same name | Support for Multiple Wikis in Oracle |
| PostgreSQL | A separate schema inside one database | Support for Multiple Wikis in PostgreSQL |
| HSQLDB | A separate schema | Evaluation only, for the reasons in HSQLDB Limitations |
Each schema, database or user is named after the wiki id. The main wiki is the exception: its database is named xwiki by default, or PUBLIC on HSQLDB, and xwiki.db in WEB-INF/xwiki.cfg forces another name.
PostgreSQL is the one database where that mapping is not a choice: the schema-per-wiki mode the shipped WEB-INF/hibernate.cfg.xml already selects is the only one that works there, and Support for Multiple Wikis in PostgreSQL gives the property and the issue that tracks the other one.
Prerequisites
- An installed XWiki instance, which becomes the farm's main wiki. Installation covers the installation methods for a reader who has none yet.
- Administration rights on that instance, because creating a wiki is an administration operation.
- One of the databases above, configured for XWiki.
- A database user that XWiki is allowed to connect as and that may create a schema, a database or a user, since creating a wiki creates one. This is the requirement most often missed, and the per-database pages above also say how to leave that privilege with a DBA instead.
Reserved Wiki Ids
A wiki id can be refused before any schema is created. xwiki.virtual.reserved_wikis in WEB-INF/xwiki.cfg holds a comma-separated list of names that may not be used when a wiki is created, and it is empty by default.
FAQ
Can a farm run on HSQLDB?
It works, and the shipped standalone distribution is a farm of one wiki on HSQLDB, but for evaluation only. The reasons are in HSQLDB Limitations, and a farm meets the first of them sooner than a single wiki does, since every wiki it holds is in the same heap.
Does each wiki need its own database user?
Only on Oracle, where a wiki is an Oracle user. XWiki still connects as one user and reaches every other wiki through that single connection, which Support for Multiple Wikis in Oracle sets out.
Can the wikis of a farm be spread over several database servers?
No. One instance has one Hibernate configuration and one connection pool, so the whole farm is stored on the DBMS that configuration points at.
