Query performance

In this session

• what is the relational in RELATIONAL database?
• how PostgresSQL handles the execution of queries
• analyze a query performance with EXPLAIN

So far

We saw

• normalizing
• window functions
• simple CTEs

Today

• A look at how PostgresSQL optimizes queries
  • query optimizer,
  • cost functions,
  • algorithms
• EXPLAIN and EXPLAIN ANALYZE to analyze the performance of queries

EOD

• everything is a relation, I mean everything
• you understand what makes a query efficient for the postgreSQL engine
• you can interpret EXPLAIN query plans

Let’s go