PgConf.Russia 2020

Cloud storage has some unique characteristics compared to traditional storage mainly because it is virtualized and controlled by software. One example is that AWS EBS shows higher throughput with larger I/O size up to 256 KiB without hurting latency. Hence, a user can get only about 4 MiB/sec with 1,000 IOPS EBS volume if the I/O request size is 4 KiB, whereas a user can get about 250 MiB/sec if the I/O request size is 256 KiB. This is because EBS consumes one I/O in a given IOPS budget for every I/O request regardless of the I/O size (up to 256 KiB). Unfortunately, PostgreSQL cannot exploit the full potential of cloud storage because PostgreSQL has designed without considering the unique characteristics of cloud storage.

In this talk, I will introduce the AppOS extension that improves the throughput of a write-intensive workload by 10x by transparently making PostgreSQL cloud storage-native. AppOS works like a storage driver that efficiently exploits the characteristics of cloud storage, such as I/O size dependency to storage throughput and latency, atomic write support in cloud block storage, and fast, but non-durable local SSDs. To do this, AppOS comprises a Linux-compatible file I/O stack including virtual file system, page cache, block I/O layer, cloud storage driver. On top of the file I/O stack, syscall module supports registering pre- and post-handler for file I/O-related system calls in order to transparently work without modifying PostgreSQL codes.

I will focus on presenting key use cases and performance results of the AppOS extension after explaining the internals. Specifically, I will show the performance results of OLTP and some batch workloads using standard benchmarking tools like pgbench and sysbench. I will also present performance results and implications on multiple clouds including AWS, GCP, and Azure.

В поиске проблем производительности администраторам баз данных необходим инструмент исторического анализа нагрузки. Особенно важен подобный инструмент в случаях, когда было зафиксировано время нехарактерного снижения производительности системы, и вам надо выяснить что больше всего нагружало вашу СУБД в это время. Это и поиск ресурсозатратных запросов, и поиск активных и растущих объектов в схеме данных, статистики использования пользовательских функций и использования temp. Существует несколько инструментов, так или иначе решающих эту задачу. Я расскажу об одном таком инструменте, который легко устанавливается в виде расширения к СУБД Postgres, легко настриавается и позволяет получить отчет о нагрузке за некоторый период в прошлом, который будет неплохой начальной точкой дальнейшего расследования.

200 баз, несколько кластеров, несколько терабайт данных Поделимся своим опытом настройки и использования patroni cluster Кластер СУБД под Linux, сервер 1С под windows. Используем: Сборка PostgreSQL для 1С, Patroni, Consul, Consul dns, Commvault, Ansible Vagrant файл и Ansible playbook c ролями прилагается.

Locking is critical for providing high concurrency for any database — you cannot fully utilize your hardware if locking is throttling its use. This talk explores all aspects of locking in Postgres by showing queries and their locks; covered lock types include row, table, shared, exclusive, and advisory lock types. The high concurrency provided by Multiversion Concurrency Control (MVCC) is also covered.

Slides are at https://momjian.us/main/writings/pgsql/locking.pdf