Why Is It Called PostgreSQL?

PostgreSQL was originally named “POSTGRES”— all caps. The name was chosen because it was the successor (“post-”) to the “Ingres” database. As the system adopted SQL standards and features, the “ql” as added and capitalization refined.

From the PostgreSQL docs:

Many people continue to refer to PostgreSQL as “Postgres” (now rarely in all capital letters) because of tradition or because it is easier to pronounce. This usage is widely accepted as a nickname or alias.

The official pronunciation is “Post-Gres-Q-L.”

Sources:

• PostgreSQL History
• PostgreSQL FAQ
• Wikipedia PostgreSQL