Spark: Faster net changelogs using identifier columns #14293
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Closes #14249
Implementation
The implementation is similar to what was initially proposed:
identifier_columns
and sort within partition byidentifier_columns + change_ordinal
RemoveCarryoverIterator
.Note: Above is the same as
net_changes
without identifier columns but with a simpler repartition spec.change_ordinal
) for each logical rowNote: Above performs the netting of the changes, we get rid of all change except for the first and last change ordinal, this is cheaper than iterating through them all. Existing
net_changes
cannot leverage this as we do not have a consistent set of identifier columns across the entire snapshot range so we need to iterate through them all to build the lineage.Note: Above is similar to existing ComputeUpdateIterator). Here we need to handle multiple INSERTS/DELETEs entries(as the intermediate changes aren't present).
Testing