Interesting Properties in Parallelism Show Plan Operator

kamingbb 2015-12-09 03:58:32

Just found in the execution plan XSD, http://schemas.microsoft.com/sqlserver/2004/07/showplan. There are three interesting properties in the Parallelism operator. Does anyone know the purpose of them?

  1. HashKeys
  2. ProbeColumn
  3. Predicate

Thanks,
Kelvin

SQLkiwi 2015-12-09 17:59:33
I haven't seen HashKeys recently enough to remember its function. I'll update this answer if I do recall it.

From memory, the Predicate (and maybe ProbeColumn) is populated when the Parallelism operator (exchange) is the site of a bitmap filter application. Again, I might update this quick answer.

HashKeys (and maybe ProbeColumn) might exist in the showplanxml.xsd for aspects that are not normally exposed, or only applicable to certain technologies that share the schema e.g. possibly Azure/Hadoop. Apparently these attributes aren't used by PDW.

kamingbb 2015-12-11 06:43:17
Thank you Paul.