VDS is scanning all the available reflections

Dremio University
1

Hi ,

I have created a VDS with reflection.
while running a select on VDS its scanning all the available reflections and then using the suitable reflection for accelerating the query.
This scanning is causing the slowness to query as there are many reflections is available is system.

Can you please suggest a way where we can point to a single reflection and avoid scanning all the reflections?

Thanks in advance

2

@KS295 Starting Dremio 4.8, default reflections should help address this, for a reflection to be qualified as a default reflection it needs to be

  • On a VDS
  • A raw reflection
  • All columns of the VDS has to be selected
  • The job should be a query

Is the reflection that is getting used a raw or an agg reflection? Also how many columns are there? Can we also get a profile where there are many reflections considered

1 Like
3

Hi Balaji,

Thank you for the quick response.

  • Yes reflection is on a VDS
  • Yes its a Raw reflection
  • Yes its using all the columns
  • Yes The job is a query.

not sure either its scanning reflection under the same folder or entire system.
Query is not running due to this.

regards,

4

@KS295

Can you please share the job profile?