Продвинутые техники pg_upgrade

When it comes to performing postgres upgrades between major versions the command line utility pg_upgrade is the most popular method used today. But as with all things wonderful, there are caveats. One of the more critical issues is what to do when there's a failure. The purpose of this talk is to present those little covered "tricks" of the trade that allows one to improve and enhance the upgrade experience.

We'll start out by reviewing its basic mode operation. We'll then learn what makes it so darn fast when upgrading multi-terabyte datacluster in a matter of minutes. Finally, you will be introduced to those feared failures and how to deal with them with confidence and certainty.

Herein is a summary of the topics in this talk:

• How pg_upgrade works: the big picture
• About pgupgrade (comand line invocation)
  • arguments and options

• The steps performing an upgrade
• About the replication ROLE
  • with replication
  • with login

• Upgrade options: COPY vs Hard Link
• Post-upgrade
  • about performance
  • aboutanalyze
  • repack
  • reindexing

• When something goes wrong at the point of no return (or is it?)
• Upgrading the REPLICA
  • default method: pg_basebackup
  • the cool method:
    • - leveraging rsync
    caveat; about vacuum wraparound

Constraints или о том, как попытаться спокойно жить

There's a common delusion that constraints should never be used as they affect performance in a negative way, interfere with regular work, and are, all in all, useless. The database is commonly perceived as just a storage without any logic. I'll explain why it isn't so and what this careless approach may lead to.

Построение автоматического консультанта и инструментов настройки производительности в PostgreSQL

PostgreSQL is a mature and robust RDBMS since it has 30 years of history. Over the year, its query optimizer has been enhanced and usually produces good query plans.

However, can it always come up with good query plans? The optimization process has to use some assumptions to produce plans fast enough. Some of those assumptions are relatively easy to check (e.g. statistics are up-to-date), some harder (e.g. correct indexes are created), and some nearly impossible (e.g. making sure that the statistic samples are representative enough even for skewed data repartition). For now, given those various caveats, DBA sometimes can't always realize easily that they miss a chance to get a meaningful performance improvement.

To help DBA to get a truly good query plan, we'll present below some tools that can help to fix some of those problems by providing a missing index adviser, looking for extended statistics to create, and row estimation error correction information to get appropriate join orders with join methods automatically.

• pg_qualstats: provides a new index and extended statistics suggestions to gather many predicate statistics on the production workload.
• pg_plan_advsr: provides alternative good query plans automatically to analyze iterative query executions information to fix estimation rows error.

In this talk, we will explain how those tools work under the hood and see what can be done, how they can work together. Also, we will mention what other tools also exist for related problems. Therefore, it will be useful for DBA who are interested in improving query performance or want to check whether current settings of indexes and statistics are adequate.

Повреждение данных: как его избежать, обнаружить и обеспечить восстановление

PostgreSQL databases can become corrupted for a variety of reasons, including hardware failure, software failure, and user error. In this talk, I’ll talk about some of my experiences with database corruption. In particular, I’ll mention some of the things which seem to be common causes of database corruption, such as procedural errors taking or restoring backups; some of the ways that database corruption most often manifests when it does occur, such as errors indicating inconsistencies between a table and its indexes or a table and its toast table; and a little bit about techniques that I have seen used to repair databases or recover from corruption, including some experiences with pg_resetxlog. This talk will be based mostly on my experiences working with EnterpriseDB customers; I hope that it will be useful to hackers from the point of view of thinking about possible improvements to PostgreSQL, and to end users from the point of view of helping them avoid, diagnose, and cope with corruption.