published by whitemice on Tue, 05/29/2018 - 15:30
The THP (Transparent Huge Pages) feature of modern LINUX kernels is a boon for on-metal servers with a sufficiently advanced MMU. However they can also result in performance degradation and inefficiently memory use when enabled in a virtual machine [depending on the hypervisor and hosting provider]. See, for example "Use of large pages can cause memory to be fully allocated".
published by whitemice on Mon, 11/18/2013 - 00:00
A powerful feature of PostgreSQL is the ability to create table spaces and to move database objects between them. Each table space represents a physical storage location; so using table spaces you can tier data onto different grades of storage [SSD vs. fast disk vs. slow disk] as well as move data from storage being retired [like an iSCSI SAN] to a new storage [a Fiber-Channel SAN!].
published by whitemice on Wed, 01/09/2013 - 00:00
One of the key steps for performing tuning a database is to test indexing strategies and their effect on performance. It is a series of:
- Drop the indexes
- Create new indexes
- Update statistics
- EXPLAIN the important queries.
Rinse and repeat.
