PostgreSQL In Memory Database
I want to run my PostgreSQL database server from memory. The reason is that on my new server, I have 24 GB of memory, and hardly any of it is used.
I know I can run this command to make a ramdisk:
mdmfs -s 1024m md2 /mnt
And I could theoretically have PostgreSQL store its data there. But the problem with this is that if the server crashes or reboots, the data will be gone.
Basically, I want the database to be loaded in memory at all times so that it does not have to go to the hard disk drive to read every record, since I have TONS of memory and since memory is faster than hard disk drives.
Is there a way to do this while also having PostgreSQL write to disk so I don't lose any data in case the server goes down? Or is there a way to cache all data in memory?
Answer
I'm now using streaming replication which is async. This means my MASTER could be running all in memory, with the separate SLAVE instance using traditional disk.
A machine restart would involve stopping the SLAVE, copying the postgresql data back into ramdisk and then restarting the MASTER followed by the SLAVE. This would be an interesting possibility which compares well with something like REDIS, but with the advantage of redundancy / hotstandby / backup / sql / rich toolset etc.