POSTGRES Query Language

• Path Expression

• Nested Queries

• Transitive Closure

  • event *

• Inheritance

  • class *

• Time Travel

Notes:

• Set-oriented query language that resembles a superset of a relational query language.
  

• Path Expression:

• retrieve(EMP.name) where EMP.dept.floor = 1

• instead of joins which would be like:

• retrieve(EMP.name) where EMP.dept = DEPT.OID and DEPT.floor = 1

• where DEPT is a constructed type.

• Transitive Closure- explode parts or ancestor hierarchy.

• Event * (retrieve, replace, delete, append, new, etc.)

• query should run until answer fails to grow.

• Class*- query should run over the class and all sub classes in the inheritance hierarchy

• Time travel-run historical queries.