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dbname
Name of the database comprising the record type for which online DBTT extension is to be performed. The database and the corresponding realm must already be attached at the time the DAL command is issued and online realm extension must be activated.
recordref
Number of the user record type for which online DBTT extension is to be performed.
You can display the recordrefs of the record types using the DAL command DISPLAY DBTT-INCR or take them from the BPSIA log.
recordref=1 is used internally by UDS/SQL and cannot be specified here.
extnmbr
Minimum number of entries by which the DBTT is to be extended. This specification must be greater than or equal to 1 and less than or equal to 99999999. If the parameter is not specified, the extension size is calculated internally.
The DAL command EXTEND DBTT performs precisely one online DBTT extension when a record of the corresponding record type is stored whether or not online DBTT extension is activated. However, for this to be possible online extensibility must be active in the realm in question and the realm must be attached. If extension is successful, message UDS0741 is issued.
Since the DAL command is not executed until the next time a record of this record type is stored, the time between the issuing of the command and the execution of the extension depends solely on when new records are stored by the active applications.
You can use DISPLAY DBTT to find out whether there is still a noted EXTEND DBTT request.
If the realm containing the DBTT is detached, then any as yet unexecuted EXTEND-DBTT request is canceled without notification to the user. In particular, such cancellations are performed when the corresponding database is disconnected or at the end of a DBH session.
The EXTEND-DBTT request is executed the next time a record is stored even if this means that two extensions may be performed close together when online DBTT extension is active because a DBTT extension is performed in parallel in another transaction as a result of the activated online DBTT extensibility.
When multiple EXTEND-DBTT request are issued one after the other before the next record of the record type concerned is stored, the DBTT extension is performed once only, namely with the last extension size specified.
As a rule the actual number of DBTT entries by which the database is extended is somewhat greater than the desired number. The actual number depends on the following factors:
Page size of the database (2K, 4K or 8K)
DBTT line length of the record type concerned
Depending on these factors there is an upper limit for the possible extension number to which the higher specifications are automatically reduced.
If bottlenecks occur in the DBTT extension, the number of entries by which the DBTT is extended can also be less than the desired number. In all cases the number of DBTT entries by which the DBTT was actually extended will be displayed with a corresponding message.
If a pending EXTEND-DBTT request fails because online realm extension has been suspended or because the maximum size of the DBTT has been reached, then the online extension to the DBTT in question is suspended in the current session segment and a corresponding error message is output. This message is output for each new EXTEND-DBTT request irrespectively of whether or not a similar message has already been issued in the current suspension segment.
If an EXTEND-DBTT request is present when online extension for the corresponding realm is deactivated, then the EXTEND-DBTT request is cancelled without any notification to the user.