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From "Jonathan Ellis (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-226) Make time-sorted CFs behave consistently
Date Wed, 17 Jun 2009 22:16:07 GMT


Jonathan Ellis commented on CASSANDRA-226:

the point is that the reason you use a time-sorted column is to get list-like behavior; you
have an append operation, basically.

I am saying, the whole concept of  "older versions" doesn't really make sense when you are
using it that way.

> Make time-sorted CFs behave consistently
> ----------------------------------------
>                 Key: CASSANDRA-226
>                 URL:
>             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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