How is the VDS's reflection refresh scheduled?

1

Hi there,
Let say I have a VDS, created from many different PDSs. Some of those PDSs have their own reflection refresh policy, or maybe all of them are set never refresh
So if I create a reflection on the VDS, how is that reflection refresh scheduled?

I visualize both cases for easier understanding as below

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image1143×509 39 KB

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image1163×514 48 KB

Thanks,

2

it shoud be
case 1: vds never refresh
case 2: refresh every 10’

you can try

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3

Thanks @flavin
So that means in case 2, the VDS will be refreshed according to the one that have shortest refresh interval? Am I correct?

4

No, case 2: will be refresh each 10’ and 30’ even the two refresh can collision beacuse 30 are multiply of 10

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5

Nice diagram! @flavin is correct. The VDS will basically refresh every 10 minutes. The way to think about when the next refresh will occur is from the POV of the VDS. The VDS knows that it depends on PDS1 and PDS2 and PDS1 has the shortest refresh period. So VDS will refresh using the shortest refresh period.

BTW, you can enable DEBUG logging on com.dremio.service.reflection to get more detailed information on when VDS is due for refresh.

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