Question

Is there a difference between pg and table lock in Oracle

Does

select * from emp for update;

results in Table lock?

And

select * from emp where deptno=10 for update;

result in page lock?

Answer 1

There is no such thing as a page lock in Oracle. Oracle has row-level locks and table-level locks.

Both of these statements create row-level locks on all the rows that the query returns. The first creates a row-level lock on every row that was in the EMP table as of the SCN where the query was executed. The second creates a row-level lock on every row that was in the EMP table with a DEPTNO of 10 as of the SCN where the query was executed. Both queries will also create a shared lock on the table that prevents other sessions from doing DDL on the table but that is rarely what people are talking about when they are talking about table locks.