On Thu, Aug 27, 2020 at 8:04 AM Greg Nancarrow <gregn4...@gmail.com> wrote: > - Parallel Copy with 1 worker ran slower than normal Copy in a couple > of cases (I did question if allowing 1 worker was useful in my patch > review).
Thanks Greg for your review & testing. I had executed various tests with 1GB, 2GB & 5GB with 100 columns without parallel mode & with 1 parallel worker. Test result for the same is as given below: Test Without parallel mode With 1 Parallel worker 1GB csv file 100 columns (100 bytes data in each column) 62 seconds 47 seconds (1.32X) 1GB csv file 100 columns (1000 bytes data in each column) 89 seconds 78 seconds (1.14X) 2GB csv file 100 columns (1 byte data in each column) 277 seconds 256 seconds (1.08X) 5GB csv file 100 columns (100 byte data in each column) 515 seconds 445 seconds (1.16X) I have run the tests multiple times and have noticed the similar execution times in all the runs for the above tests. In the above results there is slight improvement with 1 worker. In my tests I did not observe the degradation for copy with 1 worker compared to the non parallel copy. Can you share with me the script you used to generate the data & the ddl of the table, so that it will help me check that scenario you faced the problem. Regards, Vignesh EnterpriseDB: http://www.enterprisedb.com
