Hibernate LockMode
LockMode.NONE:キャッシュ用キャッシュがあり、キャッシュがない場合はデータベースからLockModeを読む.READ:直接データベースから読み、キャッシュデータを使用しないロックモード.WRITE:insert updateデータの場合、HIBERNATE内部で使用されます.以上の3つはいずれもHIBERNATEレベルのロック,すなわちキャッシュレベルのロックである.次の2つはデータベースレベルのロックです:LockMode.UPGRADE:SQL文select for updateに相当し、selectされたデータはデータベースにロックされ、他のトランザクションによって変更できません. LockMode. UPGRADE_NOWAIT:ORACLEデータベース特有のselect for update nowait
NONE
No lock required. If an object is requested with this lock mode, a
READ lock will be obtained if it is necessary to actually read the state from the database, rather than pull it from a cache.
This is the "default"lock mode.
READ
A shared lock. Objects in this lock mode were read from the database in the current transaction, rather than being pulled from a cache.
UPGRADE
Deprecated.
instead use PESSIMISTIC_WRITE
An upgrade lock. Objects loaded in this lock mode are materialized using an SQL
select ... for update.
UPGRADE_NOWAIT
Attempt to obtain an upgrade lock, using an Oracle-style
select for update nowait. The semantics of this lock mode, once obtained, are the same as
UPGRADE.
WRITE
A
WRITE lock is obtained when an object is updated or inserted. This lock mode is for internal use only and is not a valid mode for
load() or
lock() (both of which throw exceptions if WRITE is specified).
FORCE
Deprecated.
instead use PESSIMISTIC_FORCE_INCREMENT
Similiar to
UPGRADE except that, for versioned entities, it results in a forced version increment.
OPTIMISTIC
Optimisticly assume that transaction will not experience contention for entities. The entity version will be verified near the transaction end.
OPTIMISTIC_FORCE_INCREMENT
Optimisticly assume that transaction will not experience contention for entities. The entity version will be verified and incremented near the transaction end.
PESSIMISTIC_READ
Implemented as PESSIMISTIC_WRITE. TODO: introduce separate support for PESSIMISTIC_READ
PESSIMISTIC_WRITE
Transaction will obtain a database lock immediately. TODO: add PESSIMISTIC_WRITE_NOWAIT
PESSIMISTIC_FORCE_INCREMENT
Transaction will immediately increment the entity version.
NONE
public static final LockMode NONENo lock required. If an object is requested with this lock mode, a
READ lock will be obtained if it is necessary to actually read the state from the database, rather than pull it from a cache.
This is the "default"lock mode.
READ
public static final LockMode READA shared lock. Objects in this lock mode were read from the database in the current transaction, rather than being pulled from a cache.
UPGRADE
public static final LockMode UPGRADEDeprecated.
instead use PESSIMISTIC_WRITE
An upgrade lock. Objects loaded in this lock mode are materialized using an SQL
select ... for update.
UPGRADE_NOWAIT
public static final LockMode UPGRADE_NOWAITAttempt to obtain an upgrade lock, using an Oracle-style
select for update nowait. The semantics of this lock mode, once obtained, are the same as
UPGRADE.
WRITE
public static final LockMode WRITEA
WRITE lock is obtained when an object is updated or inserted. This lock mode is for internal use only and is not a valid mode for
load() or
lock() (both of which throw exceptions if WRITE is specified).
FORCE
public static final LockMode FORCEDeprecated.
instead use PESSIMISTIC_FORCE_INCREMENT
Similiar to
UPGRADE except that, for versioned entities, it results in a forced version increment.
OPTIMISTIC
public static final LockMode OPTIMISTICOptimisticly assume that transaction will not experience contention for entities. The entity version will be verified near the transaction end.
OPTIMISTIC_FORCE_INCREMENT
public static final LockMode OPTIMISTIC_FORCE_INCREMENTOptimisticly assume that transaction will not experience contention for entities. The entity version will be verified and incremented near the transaction end.
PESSIMISTIC_READ
public static final LockMode PESSIMISTIC_READImplemented as PESSIMISTIC_WRITE. TODO: introduce separate support for PESSIMISTIC_READ
PESSIMISTIC_WRITE
public static final LockMode PESSIMISTIC_WRITETransaction will obtain a database lock immediately. TODO: add PESSIMISTIC_WRITE_NOWAIT
PESSIMISTIC_FORCE_INCREMENT
public static final LockMode PESSIMISTIC_FORCE_INCREMENTTransaction will immediately increment the entity version.