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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CASSANDRA-7085) Specialized query filters for CQL3
Date Fri, 23 Oct 2015 12:18:28 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-7085?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sylvain Lebresne resolved CASSANDRA-7085.
-----------------------------------------
    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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