Many records in table SWWWIHEAD without WI_RH_TASK values

[Rivera, Raul]

We are using 4.6c and went live on Jan 1, 2004.
 
As part of our system performance monitoring, we noticed that there are
about 700,000+ records in SWWWIHEAD table (Header Table for all Work Item
Types) that have no value in WI_RH_TASK field. WI_RH_TASK contains the Task
ID.
 
Any feedback as to why we have so many records without WI_RH_TASK values
will be appreciated.
 
Thanks everyone,
 
Raul Rivera
raul.rivera at absu.accenture.com