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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] Created: (CASSANDRA-226) Make time-sorted CFs behave consistently
Date Sat, 13 Jun 2009 04:25:07 GMT
Make time-sorted CFs behave consistently
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                 Key: CASSANDRA-226
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-226
             Project: Cassandra
          Issue Type: Bug
            Reporter: Jonathan Ellis


Time-sorted CFs are indexed and sorted by time in the SSTable.  So lookup by name is inefficient,
and compaction sucks, because we combine by name even though we sort by time.

The right fix is, for time-sorted columns we need to recognize that the right "key" as it
were is (time, name) not name.  We should allow slice by time and lookup by time or time,name
but not just name.  (Similarly, we should not allow lookup by time on name-sorted CFs.)  This
means that name will not necessarily be unique in time-sorted CFs but that is the right behavior!
 Time-based CFs are more like appending to a list than putting to a map.

(As part of this we could track the most recent append in time-sorted CFs to prevent the bug
in CASSANDRA-223.  I am not sure that is the "right" way to go but I do mention it as a possibility
that this change enables.)

In the code, this will allow more regular treatment of CFs and less special casing.  (It will
also allow using only a single map for memtable columns, reducing memory usage -- see CASSANDRA-51.)

Implementation notes: we may be able to represent both types of CF with a pluggable Comparator
+ Indexer combination, which would solve CASSANDRA-185 and CASSANDRA-189 at the same time.

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