PgConf.Russia 2020

When migrating data from one DBMS to another, the question arises: choose a third-party tool or to program the migration yourself? Companies, trying to grow competencies within themselves, choose the second option. And they come across the "invention of their own bicycles". However, the market has powerful free data migration tools. One such tool is Pentaho Data Integration, part of the Pentaho Community Edition. The report will discuss the use of this package for data migration between Oracle and PostgreSQL. Particular attention will be paid to the problems with using this tool, and to the tasks of testing for the completeness and integrity of migrated data.

Small video illustration:

To build a decent query plan, the optimizer has to understand statistical characteristics of underlying data. It is interesting to observe how the structure of the collected information became more complicated over time: what the optimizer relied on back in its early days and what is at his disposal now with the release of the 12th version. We will also talk about how and when statistics are collected, how to manage this process and whether it is necessary to think about it at all.

In this tutorial, we will solve several programming problems using JSON functionality that extends SQL capabilities and virtually turns a relational database into an almost ready-to-use application server. :)
We will learn how to use aggregates, both standard and custom, as well as review possible benefits of JSON recursive structure.