PgConf.Russia 2017

Query optimization is an important problem, which solution has a great influence on DBMS performance, especially for complex queries. In this talk we consider PostgreSQL query optimizer and specifically cardinality estimation problem for correlated clauses, which is one of the most well-known drawbacks of query optimizers in general. In the talk we propose our solution for this problem which involves machine learning methods and is available for PostgreSQL 9.6 as an extension with a patch. We discuss the experimental evaluation, advantages, disadvantages, and fields of application of the proposed approach as well.

VIDEO

I love complex knowledge domains, strong typing in applications, and 3NF, but I hate ORM. That is why I’ve been actively storing serialized structures in JSON fields (even before the JSON type was introduced). In this talk, I will tell you about some specifics of storing complex structures within DBMS fields, what problems can arise, and how to cushion the blow.

VIDEO

Full text search in PostgreSQL is probably the most advanced one among relational DBMS. This tutorial will explain how to setup full text search configurations and dictionaries and how to build a ful text search system using an example of a simple popular science web site, with demonstration of various ranking functions. Also I will tell about new RUM index, which allows to accelerate execution of some kinds of full text queries and implements a new improved ranking function.

Nowadays one can make a decent urban research based simply on public datasets, making interesting and unexpected insights. In the presentation, I'll show examples of these calculations in PostGIS, the industry standard de-facto.

But just PostGIS is not enough. You need tools to import, verify and visualize the data. It's critically important to visualize the data live, to debug your calculations and shorten iterations. I'll describe all these steps:

1. Collecting the data: public API, OpenStreetMap; direct user input.
2. 3rd party APIs for calculations.
3. Visualization of GIS and other sorts of data: QGIS, Matplotlib, Zeppelin integrated with PostGIS.
4. Debugging the calculations: live visualization (Arc, QGIS, NextGIS Web)
5. Scripting and minimizing the chores: Makefile, Gulp