PGConf.Online 2021

Как будет развиваться логическая репликация?

Logical replication has been there since 10.0 and with each release, it is getting better. This talk will start with the basic architecture of Logical replication in PostgreSQL and then cover the various ways in which it can be helpful to users.

One of the shortcomings of logical replication as compare to physical replication is that currently, it allows the transaction to be replicated only once it is committed. This can create a large apply lag on the subscriber side for long-running transactions. We will discuss the solution implemented for this problem for PostgreSQL.

We will also discuss the other major work being done in logical replication which is to allow the streaming of transactions at the prepare time. This will help us in implementing conflict-free logical replication. This can be used for scaling-out reads as well. Because of 2PC, we can ensure that on subscribers we have all the data committed on the master. Now, we can design a system where different nodes are owners of some set of tables and we can always get the data of those tables reliably from those nodes, and then one can have some external process that will route the reads accordingly.

In the end, this will cover the new enhancements, improvements related to Logical Replication in recent PostgreSQL releases.

Неочевидные моменты процесса копирования и переноса баз данных и кластеров PostgreSQL

Cloning and transferring PostgreSQL databases & clusters often looks simple.

However, you can get confused while performing these simple operations, too. During my presentation, I will explain which pitfalls you may face while cloning and transferring PostgreSQL databases & clusters. We'll see what can be done to improve the performance of these operations and list the unexpected issues that arise while performing these seemingly simple operations.

Отказоустойчивый кластер PostgreSQL с помощью crmsh

Some OS distributions do not have a pcs configuration utility to create a high availability cluster PostgreSQL. In this case, the crm utility from the crmsh package will help us. It is more difficult to use, but powerful and effective.

In my master class, I will show how to use this utility, as well as configure a failover cluster in different configurations.

Бесшовная оптимизация запросов PostgreSQL, версия 2.0

There are two types of SQL query analysis:

1. "Macro": analyzing the workload as a whole (three major approaches: using metrics provided by pg_stat_statements or similar, log analysis with pgBadger or similar, and sampling of pg_stat_activity)

2. "Micro": diving into details of single query execution (EXPLAIN command being the central tool here)

And there are huge gaps between them that become noticeable at scale. The main challenges:

• Switching between "macro" and "micro" without a huge overhead
• Verifying optimization ideas reliably
• Deploying changes risk-free

Solving these tasks at a scale requires advanced DBA experience and–sometimes–intuition. Or better tools that (fortunately!) very recently started to appear.

In this tutorial, we will learn how to establish a smooth and seamless SQL optimization process in your organization: * what tools should you choose in your particular case? * how to close the gaps mentioned above?