Expected behavior when source is unavailable?

#1

Hello dear community members !

We had a maitenance downtime of our MySQL RDBMS, which is used as a Dremio source.
A lot of queries are using reflections on this source, and I was expecting that Dremio would use the reflections when Dremio source is offline, as if Dremio was online.

Instead of using reflection, Dremio does not execute the query and indicates the following message:
The source [CMS] is currently unavailable. Info: []

Is it the expected behaviour ? We are currently running Dremio CE 4.9.0.

Thanks !
Davidprofile_96f4c9aa-546b-46ef-848f-eda97e0ef41d.zip (5.0 KB)

1 Like
#2

Hi @david.lee

Yes that is expected behavior, even if the query is reflected, Dremio requires the source to be available. The reason is the planner compares costs of SQL plans when going back to the dataset versus using reflection

Thanks
Bali

#3

hi @balaji.ramaswamy ,

thanks a lot for the answer.

In my opinion it is a bit surprising, as if I want that my Analytics be highly available, I need to materialize and create copies of data reflections contents (could use CTAS on S3 for example) , which I thought was the purpose of Dremio to avoid that (ie not having to create copies).

1 Like
#4

I agree - an option would definitively be useful to choose.