I am new to ejabberd and trying to find out, how do i do full text search in history of messages for particular user? Is it possible ?
Message Archive Management XMPP specification does not support the full text query search and ejabberd does not implement something specific in that regard.
You have to implement your custom protocol and search feature. You can likely rely on database features for full-text search to make that easier (either MySQL or Pgsql)