PG LOCK_TYPE

src/include/storage/lock.h
/*


 * LOCKTAG is the key information needed to look up a LOCK item in the


 * lock hashtable.  A LOCKTAG value uniquely identifies a lockable object.


 *


 * The LockTagType enum defines the different kinds of objects we can lock.


 * We can handle up to 256 different LockTagTypes.


 */


typedef enum LockTagType


{


LOCKTAG_RELATION,/* whole relation */


LOCKTAG_RELATION_EXTEND,/* the right to extend a relation */


LOCKTAG_DATABASE_FROZEN_IDS,/* pg_database.datfrozenxid */


LOCKTAG_PAGE,/* one page of a relation */


LOCKTAG_TUPLE,/* one physical tuple */


LOCKTAG_TRANSACTION,/* transaction (for waiting for xact done) */


LOCKTAG_VIRTUALTRANSACTION, /* virtual transaction (ditto) */


LOCKTAG_SPECULATIVE_TOKEN,/* speculative insertion Xid and token */


LOCKTAG_OBJECT,/* non-relation database object */


LOCKTAG_USERLOCK,/* reserved for old contrib/userlock code */


LOCKTAG_ADVISORY/* advisory user locks */


} LockTagType;
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