question Re: Scratch file generation information in Support Questions

Scratch file generation information

JoaquinS — Fri, 16 Sep 2022 14:03:08 GMT

Hello,

A simple question:

How can I know which queries generate Scratch files?

I'm inspecting the Impalad logs and I couldn't find any information about the scratch file generation.

Regards,

Silva

Re: Scratch file generation information

Tim Armstrong — Wed, 09 Jan 2019 20:57:00 GMT

They're used for spill to disk - see https://www.cloudera.com/documentation/enterprise/latest/topics/impala_scalability.html#spill_to_disk

Re: Scratch file generation information

JoaquinS — Thu, 10 Jan 2019 16:01:44 GMT

But I need to know which specific queries spills into disk, generating the scratch files. Is possible to have that kind of information?.

Re: Scratch file generation information

Tim Armstrong — Thu, 10 Jan 2019 16:56:38 GMT

The Cloudera Manager queries page has the bytes spilled to disk as one of the metrics it tracks per query. Also in CM, there's a "Cluster utilization report" that has some aggregate information about how much data is spilled to disk over longer time windows. Also, if you're looking at the scratch files themselves the query ID is embedded in the file name (although that's an implementation detail and could change in the future).

Re: Scratch file generation information

JoaquinS — Thu, 10 Jan 2019 19:44:58 GMT

Thanks a lot for the info