http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice Software, Support, and Training for Apache Cassandra en-US Wed, 19 Jun 2013 05:49:47 +0000 http://bbpress.org/?v=1.0.3 q http://www.datastax.com/support-forums/search.php http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1360 Tue, 13 Mar 2012 00:08:33 +0000 khahn 1360@http://www.datastax.com/support-forums/ <p>Sorry you had a hard time finding the information you needed in the docs. The About Columns section of the documentation on <a href="http://www.datastax.com/docs/1.0/ddl/column_family" rel="nofollow">http://www.datastax.com/docs/1.0/ddl/column_family</a> says that each row is uniquely identified by its row key, similar to a primary key in a relational table. We need to make it clear that empty row keys are not allowed (any array of bytes will not do). Thanks for letting us know. </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1359 Mon, 12 Mar 2012 21:30:29 +0000 Anonymous 1359@http://www.datastax.com/support-forums/ <p>Ok. Is this communicated in documentation somewhere? I hit the issue because this particular app is driven by the keys from a non-nullable string primary key field from a SQL database table in my system. I assumed that no additional validation would be necessary in my application layer, which I've since fixed. </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1357 Mon, 12 Mar 2012 20:00:46 +0000 jbellis 1357@http://www.datastax.com/support-forums/ <p>Empty column values are allowed, but not empty row keys (or column names). </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1356 Mon, 12 Mar 2012 19:56:17 +0000 Anonymous 1356@http://www.datastax.com/support-forums/ <p>Ok, it makes more sense now. So Cassandra internally depends on the fact that in each cluster there must exist a token which is comparatively less than the tokens of all allowable keys, and for the provided ordered partitioners it uses plain representations of the keys as token values, so the minimum possible key has to be disallowed.</p> <p>From an external point of view this was definitely not obvious. I would not equate it to supporting null primary keys in a database. If I create a table in my SQL database with a non-nullable primary key string field, I can still create a record with an empty string primary key. The documentation (and source) for the BytesType validator also suggest that any arbitrary ByteBuffer is supported, including an empty (non-null) one. </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1354 Mon, 12 Mar 2012 18:57:01 +0000 tjake 1354@http://www.datastax.com/support-forums/ <p>Internally partitioners have a concept of a MINIMUM token, in the case of a Byte ordered partitioner we use "" as the minimum token so it is reserved. I guess for RP we technically could support "" but I would equate it to supporting null primary keys in a database which is probably a bad idea, since many apps don't ever want to have a primary key == "" </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1353 Mon, 12 Mar 2012 18:49:25 +0000 Anonymous 1353@http://www.datastax.com/support-forums/ <p>This doesn't quite make sense to me. Key + partitioner should resolve to a token which identifies where in the ring the row lives. So is there a limitation that partitioners don't have to be able to resolve tokens for empty keys? The RandomPartitioner just returns an MD5 hash of the key. Certainly it could return the MD5 hash for an empty byte string (d41d8cd98f00b204e9800998ecf8427e). Or am I missing something? </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1352 Mon, 12 Mar 2012 16:16:46 +0000 tjake 1352@http://www.datastax.com/support-forums/ <p>Yes it is intended Keys are used to identify where in the ring the row lives. So a null or empty key makes no sense. </p> http://www.datastax.com/support-forums/topic/empty-key-illegal-seeing-invalidrequestexception-on-multiget_slice#post-1350 Mon, 12 Mar 2012 14:45:55 +0000 Anonymous 1350@http://www.datastax.com/support-forums/ <p>My Java app using raw thrift is getting an InvalidRequestException when calling multiget_slice with one row key being an empty ByteBuffer. I see code in org.apache.cassandra.thrift.ThriftValidation in the validateKey method which throws InvalidRequestException if the key is empty, so it seems this is the intended behavior. Is this indeed intended? Everywhere I have found discussing row keys states that any array of bytes will do. Is there documentation somewhere stating that empty keys are invalid? (I've fixed my app to disallow empty keys at the app level but I'm still curious.) </p>