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Disabling Transparent Huge Pages in CentOS7

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".

PostgreSQL Table Spaces

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!].

Deindexing A Table (PostgreSQL)

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:

  1. Drop the indexes
  2. Create new indexes
  3. Update statistics
  4. EXPLAIN the important queries.

Rinse and repeat.

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