About Sequence Numbers

A sequence number is simply a unique identifier for an object. TIBCO iProcess® Engine uses six different types of sequence number, as shown in the following table.

Sequence Number	Stored in table...	Unique identifier for a...
o_reqid	staffo	Work item
casenum	case_information	Case
proc_id	proc_index	Procedure
wait_id	wait	Outstanding Wait
def_id	cdqp_def	CDQP definition
cfg_id	cdqp_cfg	CDQP value
monitor_id	iap_monitor	Procedure that IAP is monitoring
provider_id	eaiws_jms_provider1 Only created if TIBCO iProcess Technology Plug-ins are installed.	JMS provider
destination_id	eaiws_jms_destination2	JMS endpoints for JMS provider

These sequence numbers are generated on an “as required” basis by iProcess Engine, which calls one of the following stored database procedures:

•

sp_cdqp_cfg_sequence

•

sp_cdqp_def_sequence

•

sp_cnum_sequence

•

sp_procid_sequence

•

sp_reqid_sequence

•

sp_waitid_sequence

•

sp_iap_monitor_id_sequence

•

sp_eaiws_jms_provider_seq

•

sp_eaiws_jms_destination_seq

The procedure accesses the sequences table, increments the value of the seq_val column for the appropriate row, identified by the seq_id column, and returns that value. The returned value is then used as the next sequence number in the appropriate table.

However, getting sequence numbers directly from the database in this way can create a performance bottleneck, because while one process is requesting a number it must block any other process from attempting to do so.

To minimize the effect of this bottleneck, you can assign a cache of a block of sequence numbers to a process, by using process attributes. The process gets a sequence number from its cache when it needs one, and only accesses the database to refresh the cache when it has run out of numbers. For more information, see "Sequence Caching" in TIBCO iProcess Engine Administrator's Guide.