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Sylvain Lebresne commented on CASSANDRA-10657:
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I'll note that there is one additional optimization that I might try to do in
this ticket. For reason I lenghtily explained on CASSANDRA-7085 and similar
ticket, we have to query all columns in CQL in general, even if not all is
queried by the user, because we need to know if the row is live or not. That's
where the value skipping come from: we do query all columns, but we at least
skip the values for those for which we only care about the timestamp basically.
That said, we could fully skip the cells for columns that aren't truly
requested by the user if 1) we know the row has a "row marker" _and_ 2) the
cell in question has a timestamp lower or equal to that row marker. So I'll
probably try to see if we can use that easily on that ticket.
> Re-enable/improve value skipping
> --------------------------------
>
> Key: CASSANDRA-10657
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10657
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Fix For: 3.2
>
>
> This is a followup to CASSANDRA-10655, to re-enable the optimization of
> skipping values for the columns that are not requested by users in a CQL
> query. See CASSANDRA-10655 for why it was disabled, the goal here is to
> re-enable it minus the bugs.
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