Lockmode | Description | |
level | Specifies locking level as follows: | |
page | Specifies locking at the level of the data page (subject to escalation criteria as described below). | |
table | Specifies table-level locking. | |
session | Specifies the current default for your session. | |
system | Specifies that the DBMS Server starts with page level locking, unless it estimates that more than maxlocks pages are locked, in which case, table level locking is used. | |
readlock | Specifies lock mode for tables being read but not updated. You can specify any of the following readlock modes: | |
nolock | Specifies no locking when reading data. | |
shared | Specifies the default mode of locking when reading data. | |
exclusive | Specifies exclusive locking when reading data (useful in "retrieve-for-update" processing within a multi-query transaction). | |
session | Specifies the session default readlock. | |
system | Specifies the system readlock default. | |
maxlocks | Specifies the number of locks at which locking escalates from page level to table level. The number of locks available to you is dependent upon your system configuration. The following are valid values for maxlocks: | |
n | Specifies the number of page locks to allow before escalating to table level locking. The default is 10; n must be greater than 0. | |
session | Specifies the current maxlocks default for your session. | |
system | Specifies the system default for maxlocks. If you specify page level locking and the number of locks granted during a query exceeds the system-wide lock limit or the operating system's locking resources are depleted, locking escalates to table level. This escalation occurs automatically and is independent of the user. | |
timeout | Specifies the amount of time to wait for a lock. If the DBMS Server cannot grant the lock request within the specified time, the query that requested the lock aborts. Valid values for timeout are: | |
n | Specifies the number of seconds to wait for a lock; to specify an indefinite wait, set timeout to 0. | |
session | Specifies the session default. | |
system | Specifies the system timeout default. | |
nowait | Specifies that when a lock request is made that cannot be granted without incurring a wait, control is immediately returned to the application that issued the request. | |
Parameter | Default |
level | Dynamically determined by the DBMS Server |
readlock | Shared |
maxlocks | 50 |
timeout | 0 (no timeout) |