Postgres does something similar. Every time a query returns a row the system must do a lookup into a visibility map to see if the row is visible to the current

Postgres does something similar. Every time a query returns a row the system must do a lookup into a visibility map to see if the row is visible to the current transaction. It can also check if it's a completely dead row. If there is an index involved, then on the next row fetch Postgres will report to the index whether the last row was dead or not. The index can elect to delete the row reference, which means a write during a select statement.