PostgreSQL

MVCC shown as a familiar table view, with tuple metadata and snapshot rules attached to each row

PostgreSQL: MVCC & Transactions

Pick a walkthrough to see how PostgreSQL changes rows in a heap table without overwriting them in place.

→ rows stay in a table-like heap structure, and xmin/xmax decide which physical version a snapshot can see

How To Read This Table

Treat the main grid like a familiar database table: each row is a physical tuple, while xmin and xmax explain who created or invalidated it.

Update Row creates a new physical row version instead of overwriting the original one. Delete Row changes visibility first and leaves physical cleanup for later.

Check Visibility keeps the table front and center so you can see which physical rows exist and which one the active snapshot is actually allowed to read.