http://www.datastax.com/support-forums/topic/cql-not-working-as-expected Software, Support, and Training for Apache Cassandra en-US Wed, 19 Jun 2013 09:51:17 +0000 http://bbpress.org/?v=1.0.3 q http://www.datastax.com/support-forums/search.php http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1436 Tue, 27 Mar 2012 16:24:31 +0000 jbellis 1436@http://www.datastax.com/support-forums/ <p>"Secondary indexes allow for efficient querying by specific values using equality predicates (where column x = value y). Also, queries on indexed values can apply additional filters to the result set for values of other columns."</p> <p><a href="http://www.datastax.com/docs/1.0/ddl/indexes" rel="nofollow">http://www.datastax.com/docs/1.0/ddl/indexes</a></p> <p>More examples here: <a href="http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-indexes" rel="nofollow">http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-indexes</a> </p> http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1433 Tue, 27 Mar 2012 14:32:13 +0000 Anonymous 1433@http://www.datastax.com/support-forums/ <p>Hi,</p> <p>I am quite new to Cassandra. I am using CQL-JDBC driver. I am not able to write query which has something.</p> <p>Select * From Users where age &gt; 20</p> <p>I have created a secondary index on age. Can you please help me what is wrong ?</p> <p>Thanks,</p> <p>-Ansar </p> http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1382 Fri, 16 Mar 2012 10:57:18 +0000 Anonymous 1382@http://www.datastax.com/support-forums/ <p>Using Astyanax (instead of Thrift or Hector) I've converted the CF to using simple row id's without the hash, and moved the hash as the first part of a composite column. Works like a charm. </p> http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1375 Wed, 14 Mar 2012 16:13:49 +0000 Anonymous 1375@http://www.datastax.com/support-forums/ <p>I think I found what is happening (see below). This means that I either use super columns (which basically are depricated) or composite columns (which are not yet supported by CQL).</p> <p><a href="http://www.anuff.com/2011/02/indexing-in-cassandra.html" rel="nofollow">http://www.anuff.com/2011/02/indexing-in-cassandra.html</a></p> <p>The OrderPreservingPartitioner, as the name implies, orders the keys in string-sort order, so you can not only look up a row via a specific key, but can also traverse your set of keys in ways that are directly related to the values you are using as your keys. In other words, if your row key was a "lastname,firstname,ss#" string, you could iterate through your keys in alphabetical order by lastname. Generally, though, people try to use the RandomPartioner because, in exchange for the convenience of the OrderPreservingPartitioner, you lose the even distribution of your data across the set of nodes in your overall system, which impedes the scalability of Cassandra. </p> http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1374 Wed, 14 Mar 2012 16:05:09 +0000 Anonymous 1374@http://www.datastax.com/support-forums/ <p>I'm detecting a pattern. The rows that are found are related to the sequence in which they have been inserted. If I start with "L0000001__89eb5af1fbecabc7874de697d815d4d5" I find all three. If I start with "L0000001__" I only find the last, since it was inserted last.</p> <p>Should I be looking at creating indexes? </p> http://www.datastax.com/support-forums/topic/cql-not-working-as-expected#post-1373 Wed, 14 Mar 2012 16:00:54 +0000 Anonymous 1373@http://www.datastax.com/support-forums/ <p>I've got a simple CF which stores the result of an expression, sort of a cache, which used a prefix and a MD5 hash as the row key. At times the cache must be invalidated, so I need to scan all rows which start with the prefix, for this I wanted to use a CQL query.</p> <p>create column family LicenseXPath with comparator=UTF8Type and default_validation_class=UTF8Type and key_validation_class=UTF8Type;</p> <p>If I do a "select KEY from LicenseXPath" I get the following keys:<br /> L0000001__89eb5af1fbecabc7874de697d815d4d5<br /> L0000001_0027__89eb5af1fbecabc7874de697d815d4d5</p> <p>All keys starting with "L0000001__" must be invalidated. So I intended to do a "select KEY from LicenseXPath where KEY &gt;= 'L0000001__' and KEY &lt; 'L0000001_a'", however this returns no keys. If I leave out the second condition, no rows. No matter what I do, as soon as there is a where condition I get no rows. </p> <p>So I manually inserted the row key "L0000001__", and the select now does find that row. But only that row. </p> <p>I'm doing something wrong. Got some wires twisted. Question is: what wires? What am I missing? </p>