Performing pending requests (PERFORM)

PERFORM {NOCANCEL | CANCEL}          

Default value:

NOCANCEL

NOCANCEL

Any open transactions impeding execution of pending requests are allowed to terminate normally.
The pending (noted) requests are then executed.

CANCEL

Any open transactions impeding execution of pending requests are rolled back.

Pending requests are generated as a result of the following DAL commands: ACT INCR, ACT DBTT-INCR, ADD DB, ADD RN, CHECKPOINT, DEACT INCR, DEACT DBTT-INCR, DROP DB, DROP RN, NEW PUBSETS, NEW RLOG.

The DAL command PERFORM causes the DBH to execute all pending requests as soon as possible, allowing for consistency and any open transactions. This means that all open transactions that impede consistent execution of the pending requests must first be terminated. Such transactions can be displayed by means of DISPLAY USERS. Any new transactions of this type will be rejected with an accompanying status code.

While a consistency point is being set, all new UPDATE transactions are rejected with the status code 12122 or 12124 (the status code 12124 is listed in the case of PP ORDER-DBSTATUS=SPECIAL).

New SQL transactions can execute as RETRIEVAL transactions. SQL UPDATE statements are rejected (SQL CODE -810).

If PERFORM has been issued and all requests have not yet been fully processed, the following commands are rejected: ACT, ADD, CHECKPOINT, DEACT, DROP, NEW RLOG.

An error-free UDS/SQL pubset declaration which was checked beforehand using DAL NEW PUBSETS becomes effective with the next (DAL or DBH-internal) PERFORM. This is indicated by the following message:

UDS0754 UDS SWITCHES TO NEW PUBSET DECLARATION NOW

The processing of DAL commands is described in the section "Executing DAL commands (EXECUTE-DAL-CMD)” in chapter "UDSADM statements".

When PERFORM NOCANCEL has been specified, it may happen that processing of pending requests is unacceptably delayed by protracted transactions. To prevent lengthy delays it is possible to enter PERFORM CANCEL at a later stage.

Note on UDS-D/openUTM

With UDS-D/openUTM it is also possible for distributed transactions to delay execution of pending requests, for example if distributed transactions are left in the PTC condition. Such transactions are not affected by the PERFORM CANCEL command, so as not to compromise interconfiguration consistency or UDS/SQL openUTM consistency. In such cases the DAL command DISPLAY should be used to display the statuses of all current transactions, and if necessary an ABORT or COMMIT command should be used to intervene.