PGConf.Russia 2018

Developers are often challenged to deliver results that are hard to implement using simple SQL queries. Fortunately, complex SQL capabilities exist in the SQL standards — common table expressions and window functions.

SQL is a declarative language, meaning the user submits an SQL command and the database determines the optimal execution. Common Table Expressions (CTEs) allow queries to be more imperative, allowing looping and processing hierarchical structures that are normally associated only with imperative languages.

Normal SQL queries return rows where each row is independent of the other returned rows. SQL window functions allow queries to return computed columns based on values in other rows in the result set.

This tutorial will help developers use CTE queries in their applications and allow operations that normally could only be done in application code to be done via SQL queries. It also explains the many window function facilities and how they can be used to produce useful SQL query results.

Video

Part I «Programming the SQL Way with CTE»

Part II «Postgres Window Magic»

If you honestly evaluate most of our business applications, you will see that they first collect and import the data into a database and then send the same data in the opposite direction.

What if we don't build an ORM wall between the application and the database, but try using the symbiosis of their strong points and special features instead?

I will tell you how we use PostgreSQL and Clojure for building data-intensive medical applications. We will cover the following topics:

• functional relational programming
• jsonb for modeling complex data domains
• functional indexes and json-knife extension for jsonb search
• graphql implementation on PostgreSQL
• logical replication for building reactive integrations
• asynchronous JDBC-free connector to PostgreSQL on netty

«KNOPKA» («The button»), the largest outsourcing of accounting, will tell you about your experience of transferring 500Gb of 1C Fresh databases to PostgreSQL. The report touches on the choice of DBMS and the fight against stereotypes, where we started and how developed the use of PostgreSQL, the approaches to backup and recovery of information security, our current performance of DBMS and 1C, a look into the future. Let us share why we believe that 1C + PostgreSQL is simple, reliable and fast.

One of advantages of document-oriented databases like MongoDB or Couchbase over RDBMSs is an ability to change the data scheme easily, fast and often. The traditional approach in RDBMS world involves doing an expensive ALTER TABLE operation, slow upgrade of an existing data, and stuff like this. This approach is often slow and inconvenient for application developers.

To solve this issue PostgreSQL provides JSON and JSONB datatypes. Also there are extensions like zson and pg_protobuf. From this talk you will learn how to work with these datatypes and extensions, their pros and cons and also related future work in this area.