AUTONOMOUS PROCEDURE 0.000000 0.00 N/C PQ SYNCHRONIZATION 0.000000 0.00 N/C LOB COMPRESSION 0.003906 1.02 0.003829 FAST INSERT PIPE 0.000000 0.00 N/C TOTAL CLASS 3 0.019285 19.87 0.000970  The results from the measurements of the workload that performs SELECT operations  against compressed and non-compressed LOBs with different sizes and a varying number of  concurrent threads show a similar trend of large throughput benefits for SELECT operations,  as shown in Figure 3-3.  Select activity Figure 3-3 250 KB and 500 KB select throughputs comparison It is worth noting that the overall throughput is comparatively lower for the select case when  compared against the measurements that are inserting LOBs. This result is due to (in part)  the random nature of the select workload compared to the sequential nature of the insert  workload. In this scenario, you can see a similar trend where the throughput rate seems to degrade after  20/40 threads for compressed LOBs.  The zEDC card promises highly efficient compression of LOBs without an affect on CPU  performance. This compression is reflective of the CPU performance that was measured in  the same environment that was described in 3.1.2, “LOB compression considerations” on  page 85. Because the zEDC card allows Db2 to rely on the hardware for compression, we did not  observe any significant increase in Db2 class 2 CPU time. This result is true for select and  insert performance. We noted minor CPU time differences 0.00012 - 0.00014 seconds in the  worst-case scenarios (by using 500 KB LOBs with 80 concurrent threads). 92  IBM Db2 12 for z/OS Performance Topics CPU performance for insert and select with compressed LOBs