Hello, Mark. I continue the testing. At the attempt to load a long text file ( 4M +), the wiki suggested, that the file size should not exceed 2048K. (And did not save). At the attempt to save part of that file (some of order of 1.8M) the following message is observed:
Database error A database query syntax error has occurred. This may indicate a bug in the software. The last attempted database query was: (SQL query hidden) from within function "Revision::insertOn". Database returned error "2006: MySQL server has gone away (127.0.0.1)".
Actually, the MySQL does not seem to go away: the mediawiki respons other requests. Who sends such a message: MySQL or MediaWiki 1.21.0rc1 ? Did you try to save a long page with MediaWiki 1.21.0rc1 ?