Types of Locks ​

Yellowbrick provides various lock modes to control concurrent access to data in tables. The list of Table Level Locks is given below:

Table Level Locks ​

Access Share (AccessShareLock) ​

The SELECT command acquires a lock of this mode on referenced tables. In general, any query that only reads a table and does not modify it will acquire this lock mode.

Share Update Exclusive (ShareUpdateExclusiveLock) ​

Acquired by VACUUM (without FULL), ANALYZE,UPDATE and ALTER TABLE variants. This mode protects a table against concurrent schema changes and VACUUM runs.

Access Exclusive (AccessExclusiveLock) ​

Acquired by the DROP TABLE, TRUNCATE. ALTER TABLE also acquire a lock at this level. This mode guarantees that the holder is the only transaction accessing the table in any way.

Row Exclusive (RowExclusiveLock) ​

The commands UPDATE, DELETE and INSERTacquire this lock mode on the target table. In general, this lock mode will be acquired by any command that modifies data in a table.

Conflicting Table Level Lock Modes ​