How locking take place in oracle rac environment?

how locking take place in oracle rac environment?
Suppose from one session, user is updating and from other session same rows are being selected then how this locking take place in Oracle RAC?

user11936985 wrote:
how locking take place in oracle rac environment?
Suppose from one session, user is updating and from other session same rows are being selected then how this locking take place in Oracle RAC?In the case of one session updating and the other selecting, there is no locking issue, regardless of whether it's single instance or RAC.
The update will take appropriate table (TM) and row-level (TX) locks, but the select will not take any locks (unless it's a select for update), so, there should be no problem.
Oracle will use read consistency to guarantee that the selected results are self-consistent and consistent with the point in time of the start of the query.
Hope that helps,
-Mark

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