Index to help ordering? - Mailing list pgsql-novice

Dear all,

I have a table of some 100m rows of data. There are 5 columns of data.
When I want to look at this data I typically want to sort it by ppid
(numeric) an then by time (timestamp). This simple select can often
take 15-20 seconds. Would adding an index to these two columns make it
quicker? What is the best way to achieve increased speed for this
common select query?

Thanks

James