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From "Jaroslav Kamenik (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-11102) Data lost during compaction
Date Mon, 01 Feb 2016 14:10:39 GMT
Jaroslav Kamenik created CASSANDRA-11102:
--------------------------------------------

             Summary: Data lost during compaction
                 Key: CASSANDRA-11102
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11102
             Project: Cassandra
          Issue Type: Bug
          Components: Compaction
         Environment: Cassandra 3.2.1 (single node, 5 node cluster)
JDK 8
            Reporter: Jaroslav Kamenik
            Priority: Blocker


We have experienced data loses in some tables during few weeks since update to cassandra 3.0.
I thing I successfully found test case now. 

Step one - test table:

CREATE TABLE aaa (
    r int,
    c1 int,
    c2 ascii,
    PRIMARY KEY (r, c1, c2));

Step two - run few queries:

	insert into aaa (r, c1, c2) values (1,2,'A');
	delete from aaa where r=1 and c1=2 and c2='B';
	insert into aaa (r, c1, c2) values (2,3,'A');
	delete from aaa where r=2 and c1=3 and c2='B';
	insert into aaa (r, c1, c2) values (3,4,'A');
	delete from aaa where r=3 and c1=4 and c2='B';
	insert into aaa (r, c1, c2) values (4,5,'A');
	delete from aaa where r=4 and c1=5 and c2='B';

It creates 4 rows (select count says 4) and 4 tombstones.

Step 3 - Restart Cassandra

You will see new files written into C* data folder. I tried sstable-tools to print table structure,
it shows 4 rows, data and tombstones are there.

Step 4 - set GC grace to 1 to force tombstone removing during compaction.

alter table aaa with GC_GRACE_SECONDS = 1;

Step 5 - Compact tables

./nodetool compact

aaa files dissapeares during compaction. 
select count(*) says 0
compaction history says
... aaa  2016-02-01T14:24:01.433   329   0   {}



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