Creating a page with name MapReduce causes com.xpn.xwiki.XWikiException 3201

When editing in the wiki markup I created the following:

• [[MapReduce>>doc:Map_Reduce]] WITHOUT the _ (I'm not putting it here in case it causes this system to crash. So the string was MapReduce.

With a space there was no problem. Without the space, attempting to create a page named MapReduce did this:

Detailed information:
Error number 3201 in 3: Exception while saving document xwiki:MNEI.BigData
Wrapped Exception: Failed to commit or rollback transaction. Root cause []
com.xpn.xwiki.XWikiException: Error number 3201 in 3: Exception while saving document xwiki:MNEI.BigData
Wrapped Exception: Failed to commit or rollback transaction. Root cause []
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:693)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:174)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:167)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1381)
at com.xpn.xwiki.web.SaveAction.save(SaveAction.java:163)
at com.xpn.xwiki.web.SaveAction.action(SaveAction.java:185)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:230)...

I presume I accidentally created a page whose name matches a function used by XWiki, in other words, a reserved name.

I can send the markup and the crash log on request.