PGConf.Russia 2018

MQTT is an effective data exchange protocol for IOT devices. Based on own modified EMQTT plug-in, the IoT project architecture uses PostgreSQL as a central processing and storing system for data coming from sensors in real time. The report will provide an example of the IoT hardware and software platform solution, based up on the MQTT protocol, where PostgreSQL is responsible for key functionality, providing processing, collecting and storage of data from a distributed network of IoT devices.

Storing binary data in database tables is sometimes a good solution for a particular project. But sometimes, due to changes in conditions or insufficient consideration of decisions, such storage is becoming a real nightmare. If there is an understanding of how and where to place these data, the transition to the new solutions are often very hard, often require modification in the application code and downtime the system for migration. The presentation is a particular solution of such problems. Our extension allows to move binary data from database to the storage Ceph and not only. And does it seamless for the applications.

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»

In this talk, I will tell you the story of how a bunch of sysadmins got sick of having to resuscitate their petabyte-sized Elasticsearch cluster and decided to replace it with some tried technologies: PostgreSQL, Kafka, a bit of Redis, lots of glue, and the typical sysadmin stubbornness. The result is Bagger: the sysadmin answer to Big Data. A fast, fairly reliable, fault-tolerant store, used mostly for logging timestamped events for some amount of time. Bagger is named the Bagger series of bucket-wheel excavators, feats of German engineering and some of the largest land vehicles ever produced by man. Just like the excavators that dig through tons of material, our Bagger digs through tons data.