Run PostgreSQL in a ram disk
At a a project I am heavily relying on PostgreSQL in the unit tests. This works fine but creating and dropping databases takes quite a while which goes against the purpose of unit tests. One simple solution to this is to run PostgreSQL in a RAM disk which will make IO-heavy operations a snap.
The way I suggest works simply by
- Creating a RAM disk
- Copying the contents of the PostgreSQL directory to the RAM disk
- Mounting the RAM disk over the PostgreSQL directory
This has the clear drawback that there is no write-back of any changed data. However, as I need the data only during testing this is acceptable.
Unfortunately PostgreSQL does not support RAM-based tables otherwise this would be a much cleaner solution. Another solution would be to create a new cluster directly in the RAM disk (using
pg_createcluster). The drawback with this method is that the configuration and possibly already existing DB structures are not preserved.
This was hacked together in a few minutes but “it works for me”™ using Ubuntu 10.10.
sudo /etc/init.d/postgresql stop TMPDIR=/tmp/tmpfs; # the actual mount point for the tmpfs MOUNTPOINT=/var/lib/postgresql/; [ -d $TMPDIR ] || mkdir $TMPDIR; sudo mount -t tmpfs -o size=512M,nr_inodes=10k,mode=0777 tmpfs $TMPDIR; sudo rsync --archive $MOUNTPOINT/ $TMPDIR/; sudo mount -o bind $TMPDIR $MOUNTPOINT; sudo /etc/init.d/postgresql startTweet
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