|< < 39 > >|

Postgres MVCC

Determining visibility

Sequence of row versions

A row is inserted, updated zero or more times, then maybe deleted.

"It" may be re-inserted.

E.g., suppose we identify a row by its primary key value.

cmin	cmax	ctid	Comment
100	103	(10, 1)	This row version was updated
103	110	(10, 9)	This row version was deleted
127	0	(11, 95)	This row version was reinserted

|< < 39 > >|