PgConf.Russia 2017

< 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.

1. What is an autonomous transaction?
2. An overview of autonomous transactions in "big" DBMS: Oracle.
3. Autonomous transaction logic in Postgres Pro.
4. An overview of emulation methods for autonomous transactions in PostgreSQL.
5. Comparing performance of the built-in Postgres Pro autonomous transaction mechanism and PostgreSQL emulation methods.

VIDEO

In the data persistence layer, using PostgreSQL from the very start of development, we went all the way from a small cluster on a virtual machine to a multi-host system that provides near real-time processing of mixed OLTP/OLAP load. In this talk, I’m going to tell you about the main development stages of our analytical solution at the application and infrastructure levels, and describe the specifics of using PG that we encountered.

VIDEO

We will discuss some tricks and patterns while developing web-application architecture based on ORM technology with Postgresql functions implementation with Python Django as an example. Also we will consider some ways of building the business logic inside a database with keeping Django framework opportunities and implementation of it's built-in admin panel.

VIDEO