merge multi-value field on rollout/compaction

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Eden Borochov

Mar 31, 2022, 6:47:54 AM3/31/22
to Druid User
Hi folks, 
Need you help

Is there any way to ask druid to merge multi value dimension field on rollout?

I want to add a field to my druid table , but I don't want to increase the cardinality the current rows. 


Ben Krug

Mar 31, 2022, 1:50:52 PM3/31/22
I'm not exactly clear on what you want to do, but maybe this will be helpful.

If you currently have a multi-valued dimension (MVD), and want to add a value into it, I think it should be possible using reindexing.
(Compaction or rollup affect metrics, not dimensions, and an MVD can't be a metric afaik.)

What I think you could do is use a transform on the dimension, with array_concat to add the new value to the existing MVD (array).

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