Help with inner join: "No space left on device"

I'm not very knowledgeable in SQL programming and experience, however, I need to do a search on a PostrgeeSQL database (I'm using pgAdminIII) where I need to join two tables.

create table table_new as 
select table.x1, table.x2, table.x3, table.x4, table2.x1, table2.x5, table2.x6, table2.x1 as teste
from table inner join table2 on table.x1 = table2.x1

However, with this search I end up with the following error message:

  

ERROR: could not extend file "base / 17675 / 43101.15": No space left on device
  SQL state: 53100
  Hint: Check free disk space.

Can anyone give me a hint of how to optimize my search so that I can join the two tables I need ??