PostgreSQL as a Schemaless Database

PostgreSQL as a Schemaless Database. Christophe Pettus PostgreSQL Experts, Inc. PgDay FOSDEM 2013 Welcome! I’m Christophe.• PostgreSQL person since 1997.• Consultant with PostgreSQL Experts, Inc.• cpettus@pgexperts.com• thebuild.com• @xof on Twitter.• What’s on the menu? What is a schemaless database?• How can you use PostgreSQL to store • schemaless data? How does do the various schemaless • options perform? A note on NoSQL. Worst. Term. Ever.• It’s true that all modern schemaless • databases do not use SQL, but… Neither did Postgres before it became • PostgreSQL. (Remember QUEL?) The defining characteristic is the lack of a • fixed schema. Schematic. A schema is a fixed (although mutable • over time) definition of the data. Database to schema (unfortunate term) to • table to field/column/attribute. Individual fields can be optional (NULL).• Adding new columns requires a schema • change. Rock-n-Roll! Schemaless databases store “documents” • rather than rows. They have internal structure, but…• … that structure is per document.• No fields! No schemas! Make up whatever • you like! We are not amused. Culturally, very different from the glass • house data warehouse model. Grew out of the need for persistent object • storage… … and impatience with the (perceived) • limitations of relational databases and object-relational managers. Let us never speak of this again. There’s a lot to talk about in schemaless vs • traditional relational databases. But let’s not.