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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