I have a problem with postgresql as below: I have a server CentOS 5.9 install postgresql 8.4. It is running for my production and Data Size = 300 GB. At the moment, I need migrate all data in postgresql 8.4 to postgresql 9.4 in different server CentOS 6.6. I use method dumpall data from postgresql 8.4 and restore to postgres 9.4 but the downtime is very long and I canceled this method. Can you help me guide the method to migrate data in my case to the downtime is shortest?
Thanks you very much.