Database Administration - PostgreSQL: Up and Running - page 44

Don't Give Full OS Administrative Rights to the Postgres System
Account (postgres)
Many people are under the misconception that the postgres account needs to have full
administrative rights to the server. In fact, depending on your PostgreSQL version, if
you give the postgres account full administrative rights to the server, your database
server might not even start.
The postgres account should always be created as a regular system user in the OS with
rights just to the data cluster and additional tablespace folders. Most installers will set
up the correct permissions without you needing to worry. Don't try to do postgres any
favors by giving it more rights than it needs. Granting unnecessary rights leaves your
system vulnerable if you fall under an SQL injection attack.
There are cases where you'll need to give the postgres account write/delete/read rights
to folders or executables outside of the data cluster. With scheduled jobs that execute
batch files, this need often arises. We advise you to practice restraint and bestow only
the minimum rights necessary to get the job done.
Don't Set shared_buffers Too High
Loading up your server with RAM doesn't mean you can set the shared_buffers as
high as your physical RAM. Try it and your server may crash or refuse to start. If you
are running PostgreSQL on 32-bit Windows, setting it higher than 512 MB often results
in instability. With 64-bit Windows, you can push the envelop a bit higher and can even
exceed 1 GB without any issues. On some Linux systems, shared_buffers can't be set
higher than the compiled SHMMAX variable, which is usually quite low. PostgreSQL 9.3
changed how kernel memory is used, so that many of the issues people ran into with
kernel limitations in prior versions are nonissues in version 9.3. You can find more
details in Kernel Resources .
Don't Try to Start PostgreSQL on a Port Already in Use
If you try to start PostgreSQL on a port that's already in use, you'll see errors in your
pg_log files of the form: make sure PostgreSQL is not already running . Here are
the common reasons why this happens:
• You've already started the postgres service.
• You are trying to run PostgreSQL on a port already in use by another service.
• Your postgres service had a sudden shutdown and you have an orphan post
gresql.pid file in the data folder. Just delete the file and try again.
• You have an orphaned PostgreSQL process. When all else fails, kill all running
PostgreSQL processes and then try starting again.