Tutorial 01-What is MVCC in PostgreSQL

In this session we are going to discuss about what is mvcc in PostgreSQL? i) MVCC stands for Multi-Version concurrency control. ii) MVCC is the method PostgreSQL uses to handle data consistency when Multiple processes are accessing the same table. iii) As a simple definition is one record has multiple versions iv) MVCC is not unique for PostgreSQL, we can also achieve MVCC in Mysql (Innodb engine only), Microsoft SQL server using “ Snapshot Isolation Level”. Why we need MVCC? I) It will allow multiple users or more than one can access the same records at the same time ii) MVCC provides concurrent access to the database. iii) where readers can see the old committed version of data and once the update finished, the reader can see a newly committed version of the data. The read process and write process never block to each other. Drawbacks: - It requires more storage space to store different versions of data. We can reclaim that through maintenance activities of vacuum and vacuum full. - In the MVCC, the same data causes an update conflict because two different transactions can update the same version of the row. subscribe to our channel: ----------------------------------------- https://rebrand.ly/8z3l1y1 For doubts and queries kindly contact us on ----------------------------------------------------------------------- [email protected] Follow us: www.facebook.com/MyNotesOracleDba #mvccinpostgresql #postgresqlmvcc #whatismvccinpostgresql