Dear Anjan Dave ,
I would like to start planning on upgrading a few servers from RH8 to RH9, essentially, also upgrading Postgres from 7.3.2 to 7.4 from the OS.
There's also a box with RH7.3 (postgres 7.2.1) that could be upgraded to RH9 and Postgres 7.4.
I am not sure if I should backup (pg_dump) the databases, and do a clean install of the OS, and do a pg_restore…OR, just upgrade the OS..? This is what I do when migrating .
1. Take a file system backup of PostgreSQL "data" folder preferably with DUMP
2. Take a back up of data with
pg_dump --disable-triggers -U <USER NAME> -a -d -b -D -Fc -Z 9 -f filename.tar.gz <DATABASE NAME>
a. This will take care of blobs (Though 7.2 does not have it)
b. Make sure that your data be less than 8 GB as tar could not handle more than that
3. Yes Schema is also required to be backed up with above command and having switch as
pg_dump --disable-triggers -U <USER NAME> -s Fp -f schema.sql <DATABASE NAME>
4. Now why Schema is dumped separately to that of data
Because :
a. pg_dump will dump the schema as per its own wish and not as per the database requirement so
if a required user defined function is not in the secema dump as early as it is required your pg_restore will
abort with Xmas bells
b. In this case you can rearrange the creation of Schema as
Create functions > then table > then sequences > then views
5. Now after all stuff you have done install your new OS
initdb a new database in the same directory location as it was in the old one (i.e in the older OS)
6. Now try restore the Schema if succeeds then go to 7 else
rearrange your sql statements to satisfy the monster
7. Restore Data with
pg_restore --disable-triggers -U <USER NAME> -d <DATABASE NAME> ./filename.tar.gz
8. Now if 6 and 7 fails you have a chance reinstall the older version of postgresql and also its DUMP file to regain the data and schema again and start again from point 2 to 8
This is what I do to restore / migrate and have got 100 % results till date
Any one having a better and more reliable method please pass it on to Anjan Dave and me
We would be grateful to you
Regrads,
V Kashyap
