I reasently added a view that has a function in it that takes one column and decrypt it's data using the crypto facilty of our Mainframe and presents the decrypted data in the view.
I'm seeing some strange behavior how DB2 handles the view when selecting data from it.
We have tried severeal different sql statements that DB2 should use index-scan (as it does with the view we are trying to replace).
Instead the explain of the view shows tablescan and the queries hangs. The table behind the view has around 1.4 million rows with one encrypted column.
RMF data from the crypto facility shows that utilization (%) of 1 of 4 crypto coprocessors goes from 0.5 % up to 48.4 % on a 10 minute interval for just 4 sql queries that we executed.
Any ideas what could cause this ?
The only difference lies in the view where one column is decrypted in the view. Running the queries on the new view results in tablescan while the old view has index scan on all the same queries.