SET LOCKTYPE

Class

Manual Locking

Purpose

Determines whether locking strategies should be optimistic or pessimistic

Syntax

SET LOCKTYPE TO OPTIMISTIC | PESSIMISTIC

See Also

CHANGE(), GATHER, LOCKR, READ, REPLACE, RLOCK()

Description

The SET LOCKTYPE set command is used to determine the locking strategy when a record is updated via temporary field placeholders such as memory variables or array elements. The default Recital behavior is SET LOCKTYPE TO PESSIMISTIC. With LOCKTYPE set to PESSIMISTIC, the record must be locked (RLOCK() or LOCKR) throughout the transaction to ensure that it cannot be modified by another user before the update is made. Without a lock being placed, the state of the data cannot be guaranteed.

With LOCKTYPE set to OPTIMISTIC, then prior to a REPLACE or GATHER operation the record is compared to the buffer from the previous read. If the two differ, an error is generated and the update does not take place. The CHANGE() function can be used to check whether the record has been modified before issuing the REPLACE or GATHER commands.

Example

set locktype to optimistic
use customer
store automem
@1,1 get m.name
@2,1 get m.address
@3,1 get m.state
read
if not change()
    replace customer.name with m.name,;
      customer.address with m.address,;
      customer.state with m.state
endif

Products

Recital Database Server, Recital Mirage Server, Recital Terminal Developer