Issue with Querying Views Not Utilizing Reflections in Dremio 25.0 OSS

1

Hi Dremio Community,

I am currently validating the Dremio 25.0 OSS version and have encountered an issue that I hope to get some help with.

Issue Description:

I have three tables in my Iceberg schema for which I have created reflections. I then created a view that joins these three tables on specific conditions. When querying this view, I observed that the queries are not being routed to the reflections but are instead going directly to the Iceberg tables. This behavior is resulting in significantly longer query times.

Observations:

  • Queries on the individual tables are properly routed to the reflections, leading to optimized performance.
  • The issue only arises when querying the view created on top of these tables.

Steps Taken:

  • Created reflections for each of the three tables in the Iceberg schema.
  • Created a view that joins the three tables.
  • Queried the individual tables and observed proper routing to reflections.
  • Queried the view and observed that queries are not utilizing the reflections.

Request for Assistance:

Is there a specific configuration that needs to be set to ensure that queries on views utilize the reflections? Any guidance or troubleshooting steps would be greatly appreciated.

Thank you for your assistance.

Best regards,
Jithin Odattu

2

HI @jithin.odattu

Few things

  • Reflection matching should not be limited to Enterprise edition
  • Would be interesting to see why querying the native iceberg table is not efficient

Are you able to send the verbose profile by rerunning the query, follow below steps please

alter session set planner.verbose_profile=true;
<run your select>

Thanks
Bali

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