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User specified segmentation in Live Aggregate Projections?
edited April 2020 in General Discussion
Have you considered allowing user(s) to specify the segmentation used in Live Aggregate Projections?
Question from The shortest path to Vertica: Best practices for data warehouse migration & ETL
I suppose someone like @ChuckB can answer this to more detail than me - but:
If you remember what an optimised flow of data looks like in a GROUP BY operation: the rows to be grouped are all on the same node to avoid global resegmentation - which will define how to segment the new projection, and they are sorted by the grouping columns, to allow for a pipelined group-by, and this will define how the new projection will be sorted. Any attempt to change that will invariably cost you a higher price than any benefits you might get out of it ...
In addition, we want a lot of operations on LAPs to be node-local, including how aggregation gets completed.