Home > Storage > PowerFlex > White Papers > Dell APEX Block Storage for Azure: PostgreSQL Deployment and Performance on Kubernetes > Use case 1: Select-only workload
Pgbench uses the ‘-b select-only’ option for running a SELECT statements or a read-only workload. The number of concurrent database sessions and worker threads are variables that can be changed based on the type of Azure SDC instance that is used for the compute node. The following example shows the pgbench parameters that were used to run select-only workload on the PostgreSQL databases:
#pgbench --host <hostname> -U <username> -c <No. of concurrent sessions> -j <No. of worker threads> -T <No. of seconds to test the run> -b select-only <database name> -p <port-number>
The test process runs the select-only workload by increasing the number of concurrent database sessions gradually to achieve maximum physical read IOPS with Dell APEX Block storage volume read latency near to one millisecond.
The following figure shows that the physical read IOPS increases with the number of concurrent database sessions for a select-only workload.
The following figure shows that Dell APEX Block Storage can achieve a sustained rate of 270,000 physical read IOPS during the select-only workload with 500 concurrent database sessions. The PowerFlex manager dashboard shows that there is no bottleneck at Dell APEX Block Storage when tests are conducted.
Note: Benchmark results depend on the workload type, Azure VM Instance type, placement of instances in a multi-AZ configuration, specific application requirements, and system design implementation. All performance data in this report was obtained in a rigorously controlled environment. System performance results obtained in other operating environments might vary.