UII and PJI?

Analytics

UII and PJI?

Hi All

Could anyone please advise as to what are UII and PJI while calculating the query cost and how to calculate these parameters, thanks.

Regards.

AH.

2 REPLIES
Teradata Employee

Re: UII and PJI?

PJI (Product Join Indicator) = CPU * 1000 divided by I/O.

UII (Unnecessary I/O Indicator) = I/O divided by (CPU * 1000).

The metrics are used to make an idea about query efficiency for consuming CPU and I/O resources.  

If PJI is relatively high for a query, then the query takes many CPUs for the given number of I/Os.  Maybe there is a Product Join in the Explain.   Hence the name of the metric.

If UII is relatively high for a query, then it could mean that many I/O blocks are read, but relatively low number of rows actually processed.   If it is a full table scan with only a few rows qualifying, then an index could reduce the I/O consumption in this case. 

Both metrics are available in Viewpoint's Query Monitor portlet.   And they can be calculated in DBQL by using AMPCpuTime and TotalIOCount fields.     

Teradata Employee

Re: UII and PJI?

p.s. earlier these metrics were known as LHR (Larry Higa Ratio) and HLR (Higa Larry Ratio), named after the Teradata performance tuning expert Larry Higa.