PgConf.Russia 2017

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

Dalibo team produces open source tools for PostgreSQL among other things for many years now (see http://dalibo.github.io/).

This time I'll present temBoard, a new tool to remotely control PostgreSQL databases. The project is visible at https://github.com/dalibo/temboard

It's about monitoring, supervision, remote settings and actions... and many more features to come. The main goal is to provide a comprehensive console for PostgreSQL. It's needed by production DBAs, to daily achieve their tasks. We heard Dalibo's customers, as many of them wrote the specs :-)

< Query failed: ERROR: deadlock detected
< DETAIL: Process 17371 waits for ShareLock on transaction 102733872; Blocked by process.
< Process 10414 waits for ShareLock on transaction 102733874; Blocked by process 17371.

Such "unpleasant" messages from the server can seriously puzzle the developer. When working with locks, in particular, with transactions in general, it is necessary to take into account the features of the implementation of client libraries, which can cause the above exception.

In the short talk, the mechanics of the interaction of locks will be explained, main attention being paid to causes of deadlocks. References to the relevant documentation pages will be given. A technique of "bypassing" this problem of concurrent data access will be described and illustrated with some generalized examples from practice are shown. The talk will be interesting to database developers and administrators as well as the client-side application developers.

The report is focused on the topic of automation of migration to PostgreSQL from other databases using Ispirer Migration and Modernization Toolkit. The issues of data and SQL code migration, conversion of client applications, embedded SQL and database API will be covered, the examples of implemented projects of migration from Oracle to PostgreSQL and from Microsoft SQL Server to PostgreSQL will be given.

VIDEO