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https://issues.apache.org/jira/browse/CASSANDRA-71?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis updated CASSANDRA-71:
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Attachment: 71.patch
Add range query support, which requires using an OrderPreservingPartitioner.
(Keys are returned in the order defined by the partitioner collation.) The
fundamental approach (in table.getKeyRange) is simple: create a
CollatedIterator [See
http://commons.apache.org/collections/api/org/apache/commons/collections/IteratorUtils.html#collatedIterator(java.util.Comparator,%20java.util.Collection)]
that will return unique keys from different sources, each of which is already
sorted. Then we just need Iterators for different key sources.
For SSTables, this means adding seekTo and an Iterator interface to FileStruct.
For Memtable, this means adding a DestructivePQIterator since unlike SSTable
keys those are not inherently ordered already. This means that we only do M
log N work sorting the memtable keys where M is the number of keys we actually
read, and N is the total number of keys, where a naive sort-everything-first
iterator would be N log N.
This does not implement ranges spanning multiple nodes. I will implement that
for another ticket.
> Range query support
> -------------------
>
> Key: CASSANDRA-71
> URL: https://issues.apache.org/jira/browse/CASSANDRA-71
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Fix For: 0.3
>
> Attachments: 71.patch
>
>
> Scan for keys by range (between X and Y) or prefix (starting with P).
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