Technical data

READY
18. Figure 4–1 summarizes the effects of the allow and access options on
concurrent run units readying the same realm-name. A database exception
condition will occur if a concurrent run unit has a realm-name readied in a
conflicting or incompatible mode (see Technical Notes).
The First Run Unit column refers to a READY statement that has already
been executed in a concurrent run unit. The Second Run Unit column
refers to a READY statement being attempted by the current run unit.
The intersection indicates whether the attempted READY statement can be
executed immediately or if there is a conflict.
Because Figure 4–1 is symmetrical, the chronology of access (that is, did the
First Run Unit ready the realm first) does not matter.
The locking effects of the BATCH RETRIEVAL usage mode are equivalent
to those of the CONCURRENT RETRIEVAL usage mode; however, BATCH
RETRIEVAL performs no record locking.
The locking effects of the BATCH UPDATE usage mode are equivalent to
those of the EXCLUSIVE UPDATE usage mode.
Note also that the two EXCLUSIVE usage modes have identical locking
effects.
Figure 4–1 Usage Mode Conflicts
ZK−1411A−GE
First
Run
Unit
Second
Run
Unit
Retrieval
Concurrent
Retrieval
Protected
Retrieval
Exclusive
Update
Concurrent
Update
Protected
Update
Exclusive
Yes Yes No Yes Yes No
Yes Yes No No No No
No No No No No No
Yes No No Yes No No
Yes No No No No No
No No No No No No
RETRIEVAL
CONCURRENT
RETRIEVAL
PROTECTED
RETRIEVAL
EXCLUSIVE
UPDATE
CONCURRENT
UPDATE
PROTECTED
UPDATE
EXCLUSIVE
Yes = The second READY statement is allowed to execute immediately. The two run units are
No = The second READY statement is not allowed to execute immediately. The two run units are
compatible.
incompatible.
Technical Notes
READY statement execution can result in these DB-CONDITION database
exception condition codes:
DBM$_ALLREADY All subschema realms are already readied.
DBM$_READY Realm-name is already readied.
Procedure Division 4–51