PostgreSQL uses MVCC to handle concurrent clients through snapshots instead of locks. This lets the server handle a larger amount of transaction load. In this webinar, Martín talked about how MVCC works in PostgreSQL, the pros and cons that come from it, and why VACUUM and FREEZE are very common words in the PostgreSQL community. The following topics were covered:
- Overview of MVCC.
- What “xmin” and “xmax” system columns store?
- Usage of “VACUUM” for clean up.
- “autovacuum” for automated clean-up.
- Visibility of rows, frozen rows and “VACUUM FREEZE”.