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From "Sylvain Lebresne (JIRA)" <>
Subject [jira] [Created] (CASSANDRA-7085) Specialized query filters for CQL3
Date Thu, 24 Apr 2014 16:32:17 GMT
Sylvain Lebresne created CASSANDRA-7085:

             Summary: Specialized query filters for CQL3
                 Key: CASSANDRA-7085
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Sylvain Lebresne
             Fix For: 3.0

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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