Help Center > > Developer Guide> Query Performance Optimization> Tuning Queries> Configuration SMP> Other Factors Affecting SMP Performance

Other Factors Affecting SMP Performance

Updated at: May 15, 2019 GMT+08:00

Besides resource factors, there are other factors that impact the SMP parallelism performance, such as unevenly data distributed in a partitioned table and system parallelism degree.

  • Impact of data skew on SMP performance

    Serious data skew deteriorates parallel execution performance. For example, if the data volume of a value in the join column is much more than that of other values, the data volume of a parallel thread will be much more than that of others after Hash-based data redistribution, resulting in the long-tail issue and poor parallelism performance.

  • Impact on the SMP performance due to system parallelism degree

    The SMP feature uses more resources, and unused resources are decreasing in a high concurrency scenario. Therefore, enabling the SMP parallelism will result in serious resource compete among queries. Once resource competes occur, no matter the CPU, I/O, memory, or network resources, all of them will result in entire performance deterioration. In the high concurrency scenario, enabling the SMP will not improve the performance effect and even may cause performance deterioration.

Did you find this page helpful?

Submit successfully!

Thank you for your feedback. Your feedback helps make our documentation better.

Failed to submit the feedback. Please try again later.

Which of the following issues have you encountered?







Please complete at least one feedback item.

Content most length 200 character

Content is empty.

OK Cancel