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From "Tommy Stendahl (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-12090) Digest mismatch if static column is NULL
Date Mon, 27 Jun 2016 13:19:51 GMT
Tommy Stendahl created CASSANDRA-12090:
------------------------------------------

             Summary: Digest mismatch if static column is NULL
                 Key: CASSANDRA-12090
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12090
             Project: Cassandra
          Issue Type: Bug
            Reporter: Tommy Stendahl
            Assignee: Tommy Stendahl
         Attachments: trace.txt

If a table has a static column and this column has a null value for a partition a SELECT on
this partition will always trigger a digest mismatch, but the following full data read will
not trigger a read repair since there is  no mismatch in the data.

This can be recreated using a 3 node ccm cluster with the following commands:
{code:sql}
CREATE KEYSPACE foo WITH replication = {'class': 'NetworkTopologyStrategy', 'dc1': '3' };
CREATE TABLE foo.foo ( key int, foo int, col int static, PRIMARY KEY (key, foo) );
CONSISTENCY QUORUM;
INSERT INTO foo.foo (key, foo) VALUES ( 1,1);
TRACING ON;
SELECT * FROM foo.foo WHERE key = 1 and foo =1;
{code}
I have added the trace in an attachment. In the trace you can see that digest read is performed
and that there is a digest mismatch, but the full data read does not result in a mismatch.
Repeating the SELECT statement will give the same trace over and over.
The problem seams to be that the name of the static column is included when the digest response
is calculated even if the column has no value. When the digest for the data response is calculated
the column name is not included.
I think the can be solved by updating {{UnfilteredRowIterators.digest()}} so excludes the
static column if it has no value. I have a patch that does this, it merges to both 3.0 and
trunk. 



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