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From "Tupshin Harper (JIRA)" <>
Subject [jira] [Created] (CASSANDRA-6167) Add end-slice termination predicate
Date Tue, 08 Oct 2013 21:22:41 GMT
Tupshin Harper created CASSANDRA-6167:

             Summary: Add end-slice termination predicate
                 Key: CASSANDRA-6167
             Project: Cassandra
          Issue Type: Improvement
          Components: API, Core
            Reporter: Tupshin Harper
            Priority: Minor

When doing performing storage-engine slices, it would sometimes be beneficial to have the
slice terminate for other reasons other than number of columns or min/max cell name.

Since we are able to look at the contents of each cell as we read it, this is potentially
doable with very little overhead. 

Probably more challenging than the storage-engine implementation itself, is to come up with
appropriate CQL syntax (Thrift, should we decide to support it, would be trivial).

Two possibilities ar
1) special where function:
SELECT pk,event from cf WHERE pk IN (1,5,10,11) AND partition_predicate({predicate})
or a bigger language change, but i think one I prefer. more like:
2) SELECT pk,event from cf where pk IN (1,5,10,11) UNTIL PARTITION event {predicate}

Neither feels perfect, but I do like the fact that the second one at least clearly states
what it is intended to do.

By using "UNTIL PARTITION", we could re-use the UNTIL keyword to handle other kinds of early-termination
of selects that the coordinator might be able to do, such as stop retrieving additional rows
from shards after a particular criterion was met.

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