PGConf.Russia 2022

This presentation is about NULLs implementation in the Postgres database: - What is NULL? - How is it handled by various Postgres functions? - How are NULLs stored in the database? - Indexing of NULLs

The volume of data stored in Postgres Pro databases is growing rapidly. In some organizations, such databases have already exceeded tens of terabytes in size. The existing approaches to backups don't ensure timely backup and restore of data in such cases. We have supplemented the well-known and well-tested Postgres Pro backup tools with functionality that will allow users to backup and restore large databases. In addition to that, we have created our solution with the convenience of DBAs in mind.

PostgreSQL has a number of peculiarities that you need to take into account not only while maintaining your database but also when designing your database schema. Experienced PostgreSQL are well aware of vacuuming process. On the web one can find tons of materials covering its internals, configurations and monitoring. Many valuable talks about vacuum were given at numerous conferences. However, we still face the common wraparound problem when the maximum possible number of transactions (xid) is reached. It happens even on databases that are relatively small in size. In my presentation, I will share a customer case that looks interesting to me. A chain of mistakes made at different stages of the database's life cycle once caused a disaster. The database fully stopped for one week, we detected a wraparound and spotted corrupted blocks. Maintenance was problematical, and we spent sleepless nights in search of a solution. We managed to achieve a local win as we finally restored the database, but it's not the end of this story, which makes it even more interesting.