>>-LOCK TABLE--+-table---+--IN--+-SHARE-----+--MODE------------><
               '-synonym-'      '-EXCLUSIVE-'
 

You can use LOCK TABLE to lock a table if either of the following is true:

• You are the owner of the table.
• You have Select privilege on the table or on a column in the table, either from a direct grant or from a grant to PUBLIC.

The LOCK TABLE statement fails if the table is already locked in EXCLUSIVE mode by another process, or if you request an EXCLUSIVE lock while another user has locked the same table in SHARE mode.

The SHARE keyword locks a table in shared mode. Shared mode gives other processes read access to the table but denies write access. Other processes cannot update or delete data if a table is locked in shared mode.

The EXCLUSIVE keyword locks a table in exclusive mode. This mode denies other processes both read and write access to the table. Exclusive-mode locking automatically occurs during the ALTER INDEX, ALTER TABLE, CREATE INDEX, DROP INDEX, RENAME COLUMN, RENAME TABLE, START VIOLATIONS TABLE, STOP VIOLATIONS TABLE, and TRUNCATE statements.