Shared and exclusive locks

Learn shared vs exclusive locks.

Shared and Exclusive

A shared lock allows reads, an exclusive lock only one operation.

-- Shared: SELECT (okuma kilidi)
-- Exclusive: UPDATE/DELETE (yazma kilidi)

Shared reads, exclusive writes.

Multiple shared locks can coexist. An exclusive lock is alone.

Readers don't block each other, but while one transaction writes (exclusive), others wait to read or change that row.

Exclusively lock a row with SELECT ... FOR UPDATE.

Show example solution

SELECT * FROM accounts WHERE id = 1 FOR UPDATE;

Exclusive

____ → yazma kilidi

Show answer

Exclusive → yazma kilidi

Next lesson: Deadlock