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A comment on Why Vertica Customers Adopt Apache Druid for Real-Time Analytics. Parent comment

Re:Why Vertica Customers Adopt Apache Druid for Real-Time An... by sa46 on Tuesday March 31, 2020 @03:53PM (#22741755)
The Procella[1] paper took a different approach to experiments. They embedded an experiment ID array in table rows and indexed the rows by experiment ID with a postings list.

Replex looks really neat. I've only skimmed the Acolyer summary so far. What's the difference between a replex and multiple projections of data with different partitions and sort-orders used in C-store and Vertica?

[1]: http://www.vldb.org/pvldb/vol12/p2022-chattopadhyay.pdf

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Re:Why Vertica Customers Adopt Apache Druid for Real-Time An... by gopalv on Tuesday March 31, 2020 @07:16PM (#22743823)
> What's the difference between a replex and multiple projections of data with different partitions and sort-orders used in C-store and Vertica?

The 3-replicas for failure tolerance are reused, so that the first 3 ordering projections don't add storage costs to the system.

Also the paper doesn't mention it, but the rebuild traffic is also better distributed on failure if the failure of a replica causes a rebuild that draws from a wider set of machines rather than a single one.

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