I have been needing to upgrade the PostgreSQL servers at my work for awhile now and was finally forced to do so after needing some of the features available with PostgreSQL 8.4.X. Currently we are running PostgreSQL 8.3.10 which is super old but it is definitely not the latest stable release available. One thing I am looking forward to testing is the improvements to the vacuum process. Over the past two years I have become a lot more familiar with Postgres and one thing that has been disappointing is the downtime involved in reclaiming disk space via data removed from PSQL database tables. The full vacuum process, which is required to reclaim disk after deleting data from a table, in 8.3 requires a lock on tables which essentially causes downtime. When you are dealing with large tables over 10GB in size this can take days to complete. Follow the directions below to first backup all of your PostgreSQL data, remove the current PostgreSQL installation, and then install PostgreSQL 8.4 on a CentOS Linux server.