PostgreSQL 12 High Availability Cookbook - Third Edition

How to do it...

We can collect some of the information we want from PostgreSQL if we have an install already. Follow these steps if there's an existing database instance that we can use:

1. Execute the following query to obtain the size of all databases in the instance:

SELECT pg_size_pretty(sum(pg_database_size(oid))::BIGINT) 
  FROM pg_database; 

2. Multiply the result by eight.

If we don't have an existing database, we should use a size estimate of the database install after 3 years. Refer to the Sizing storage recipe to obtain this estimate. Then, perform the following steps:

1. Divide the current or estimated database storage size by ten to obtain the minimum amount of memory.
2. Multiply our ideal CPU chip count by four to get the memory module ...