Specific topics will likely include:

• a brief summary of the lifecycle of a query in PostgreSQL and the role of the query optimizer
• the "iterator model", which is the interface used to communicate data and exchange control flow in the query executor
• scan evaluation
  • sequential scans and index scans
  • bitmap scans
  • predicate evaluation
  • materialization
  • evaluating subqueries and set-returning functions
• join evaluation
  • nested loops, hash joins, sort-merge joins
  • outer joins
• aggregate evaluation
  • grouping via sorting
  • grouping via hashing
• how to understand the output of EXPLAIN