cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Stu Hood (JIRA)" <>
Subject [jira] Commented: (CASSANDRA-1339) add support for GT, GTE index expressions
Date Mon, 11 Oct 2010 03:00:27 GMT


Stu Hood commented on CASSANDRA-1339:

Actually, I'm not sure why a KEYS index would need to query more nodes for GT/GTE/LT/LTE than
it does for EQ: locally, the operation is a merge of all index values that match the predicate,
and the merged values should be completely consumed before querying the next node, right?

> add support for GT, GTE index expressions
> -----------------------------------------
>                 Key: CASSANDRA-1339
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>             Fix For: 0.7.1
> this will require hitting every node in the cluster and merging results, unlike with
> For instance, say we have the following index rows for some hypothetical column C1:
> Node 1, ('' - M]
> 4: A G K 
> 5: B F J M
> Node 2, (M - '']
> 4: N P X
> 5: Q R T
> Because we store the index columns sorted in partitioner order, queries for C1=4 can
scan first node 1, then if insufficient data is found, proceed to node 2.  But for GT or GTE
queries we have to scan everyone and merge.  (Since we don't know what the next value after
4 is.  So an alternative would be for each node to send back, along with the data for the
first row, the row key that comes next.  This would be very very messy.)
> Note that since we don't yet support range scans backwards, we can't support LT or LTE
queries.  The easiest workaround there would be to add a way to specify that you want to create
an index on the comparator, reversed.  This is also worth doing for optimizations within normal
columns -- see CASSANDRA-1338.

This message is automatically generated by JIRA.
You can reply to this email to add a comment to the issue online.

View raw message