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https://issues.apache.org/jira/browse/CASSANDRA-7085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sylvain Lebresne resolved CASSANDRA-7085.
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Resolution: Won't Fix
As I've lengthily explained above, the initial idea of that ticket doesn't
work. So closing, but if someone has a concrete idea on how to improve the
situation we were trying to improve on this ticket, feel free to open a new
ticket with said idea. Personally, CASSANDRA-6588 is the "best" solution I can
see so far.
> Specialized query filters for CQL3
> ----------------------------------
>
> Key: CASSANDRA-7085
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7085
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Sylvain Lebresne
> Labels: cql, perfomance
> Fix For: 3.x
>
>
> The semantic of CQL makes it so that the current {{NamesQueryFilter}} and
> {{SliceQueryFilter}} are not always as efficient as we could be. Namely, when
> a {{SELECT}} only selects a handful of columns, we still have to query to
> query all the columns of the select rows to distinguish between 'live row but
> with no data for the queried columns' and 'no row' (see CASSANDRA-6588 for
> more details).
> We can solve that however by adding new filters (name and slice) specialized
> for CQL. The new name filter would be a list of row prefix + a list of CQL
> column names (instead of one list of cell names). The slice filter would
> still take a ColumnSlice[] but would add the list of column names we care
> about for each row.
> The new sstable readers that goes with those filter would use the list of
> column names to filter out all the cells we don't care about, so we don't
> have to ship those back to the coordinator to skip them there, yet would know
> to still return the row marker when necessary.
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