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https://issues.apache.org/jira/browse/CASSANDRA-1472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003216#comment-13003216
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Stu Hood edited comment on CASSANDRA-1472 at 4/12/13 5:23 AM:
--------------------------------------------------------------
tjake: Yea: opening a separate ticket to discuss a generic file format makes
sense.
----
I had a realization about this implementation of secondary indexes: I was
originally thinking we'd be able to push all boolean queries down to the
indexes on a per-sstable basis, but this is unfortunately not the case. We will
not be able to push 'AND' on separate indexes down to the sstables themselves:
we'd need to join the index from all sstables, since a row might contain one
clause in one sstable, and another clause in another sstable.
EDIT: This is roughly equivalent to what we'd need to do with a KEYS index
(seek-wise), meaning that the advantage is mostly in space utilization and lack
of locks.
EDIT2: So, there _is_ a way to execute AND queries directly per SSTable, but it
involves some uncertainty. For a particular row, if a value involved in a
multi-clause-query is NULL in a particular SSTable, then you have to accept the
row as a possible match, and resolve the uncertainty later. I'm sure there is a
way to incoporate the CASSANDRA-2498 timestamp resolution as well, although it
doesn't occur to me at the moment.
was (Author: stuhood):
tjake: Yea: opening a separate ticket to discuss a generic file format
makes sense.
----
I had a realization about this implementation of secondary indexes: I was
originally thinking we'd be able to push all boolean queries down to the
indexes on a per-sstable basis, but this is unfortunately not the case. We will
not be able to push 'AND' on separate indexes down to the sstables themselves:
we'd need to join the index from all sstables, since a row might contain one
clause in one sstable, and another clause in another sstable. EDIT: This is
roughly equivalent to what we'd need to do with a KEYS index (seek-wise),
meaning that the advantage is mostly in space utilization and lack of locks.
> Add bitmap secondary indexes
> ----------------------------
>
> Key: CASSANDRA-1472
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1472
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Stu Hood
> Attachments: 0.7-1472-v5.tgz, 0.7-1472-v6.tgz, 1472-v3.tgz,
> 1472-v4.tgz, 1472-v5.tgz, anatomy.png,
> ASF.LICENSE.NOT.GRANTED--0001-CASSANDRA-1472-rebased-to-0.7-branch.txt,
> ASF.LICENSE.NOT.GRANTED--0019-Rename-bugfixes-and-fileclose.txt,
> v4-bench-c32.txt
>
>
> Bitmap indexes are a very efficient structure for dealing with immutable
> data. We can take advantage of the fact that SSTables are immutable by
> attaching them directly to SSTables as a new component (supported by
> CASSANDRA-1471).
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