Akonadi: change to use postgres

Hi
Anyone know of any standard details instructions on how to change to postgres? I'm not a db person so I wouldn;t know where to start.  I don't mind losing history of current emails as its just for mailing lists.
The reason being is that i've started to get the "Retrieving Folder contents.." hangups now and again from which is doesn't seem to recover (there is zero akonadi activity on "System Activity").   If I then exit while its "hung" and do an alkonadictl fsck/vacuum it locks up once it displays the message "optimizing table CollectionTable..." and never returns to the command line.

Regards

Ian
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