PostgreSQL vs MySQL memory consumption / efficiency

view full story

http://serverfault.com – I have the flexibility to use whichever db version and type I'd like to use for a project given the choice between MySQL and PGSQL. I will be operating on a vps that is limited to about 1.5 GB RAM and have to run Rails via unicorn on the same server. The actual database size will be landing at about 20GB, but that data is rarely accessed. Really only the most recent 20k rows of data will ever be accessed in the big table of data, while all other tables are relatively small. I'm very curious about which database is CURRENTLY most efficient in resource utilization, particularly focused on (HowTos)