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From "Alex Petrov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-12756) Duplicate (cql)rows for the same primary key
Date Tue, 11 Oct 2016 16:14:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-12756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15565868#comment-15565868
] 

Alex Petrov commented on CASSANDRA-12756:
-----------------------------------------

In {{3.8}}: [CASSANDRA-12144].

> Duplicate (cql)rows for the same primary key
> --------------------------------------------
>
>                 Key: CASSANDRA-12756
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12756
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Compaction, CQL
>         Environment: Linux, Cassandra 3.7 (upgraded at one point from 2.?).
>            Reporter: Andreas Wederbrand
>            Priority: Minor
>
> I observe what looks like duplicates when I run cql queries against a table. It only
show for rows written during a couple of hours on a specific date but it shows for several
partions and serveral clustering keys for each partition during that time range.
> We've loaded data in two ways. 
> 1) through a normal insert
> 2) through sstableloader with sstables created using update-statements (to append to
the map) and an older version of SSTableWriter. During this processes several months of data
was re-loaded. 
> The table DDL is 
> {code:title=create statement|borderStyle=solid}
> CREATE TABLE climate.climate_1510 (
>     installation_id bigint,
>     node_id bigint,
>     time_bucket int,
>     gateway_time timestamp,
>     humidity map<int, float>,
>     temperature map<int, float>,
>     PRIMARY KEY ((installation_id, node_id, time_bucket), gateway_time)
> ) WITH CLUSTERING ORDER BY (gateway_time DESC)
>     AND bloom_filter_fp_chance = 0.01
>     AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
>     AND comment = ''
>     AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32', 'min_threshold': '4'}
>     AND compression = {'chunk_length_in_kb': '64', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}
>     AND crc_check_chance = 1.0
>     AND dclocal_read_repair_chance = 0.1
>     AND default_time_to_live = 0
>     AND gc_grace_seconds = 864000
>     AND max_index_interval = 2048
>     AND memtable_flush_period_in_ms = 0
>     AND min_index_interval = 128
>     AND read_repair_chance = 0.0
>     AND speculative_retry = '99PERCENTILE';
> {code}
> and the result from the SELECT is
> {code:title=cql output|borderStyle=solid}
> > select * from climate.climate_1510 where installation_id = 133235 and node_id =
35453983 and time_bucket = 189 and gateway_time > '2016-08-10 20:00:00' and gateway_time
< '2016-08-10 21:00:00' ;
>  installation_id | node_id  | time_bucket | gateway_time             | humidity | temperature
> -----------------+----------+-------------+--------------------------+----------+---------------
>           133235 | 35453983 |         189 | 20160810 20:23:28.000000 |  {0: 51} | {0:
24.37891}
>           133235 | 35453983 |         189 | 20160810 20:23:28.000000 |  {0: 51} | {0:
24.37891}
>           133235 | 35453983 |         189 | 20160810 20:23:28.000000 |  {0: 51} | {0:
24.37891}
> {code}
> I've used Andrew Tolbert's sstable-tools to be able to dump the json for this specific
time and this is what I find. 
> {code:title=json dump|borderStyle=solid}
> [133235:35453983:189] Row[info=[ts=1470878906618000] ]: gateway_time=2016-08-10 22:23+0200
| del(humidity)=deletedAt=1470878906617999, localDeletion=1470878906, [humidity[0]=51.0 ts=1470878906618000],
del(temperature)=deletedAt=1470878906617999, localDeletion=1470878906, [temperature[0]=24.378906
ts=1470878906618000]
> [133235:35453983:189] Row[info=[ts=-9223372036854775808] del=deletedAt=1470864506441999,
localDeletion=1470864506 ]: gateway_time=2016-08-10 22:23+0200 | , [humidity[0]=51.0 ts=1470878906618000],
, [temperature[0]=24.378906 ts=1470878906618000]
> [133235:35453983:189] Row[info=[ts=-9223372036854775808] del=deletedAt=1470868106489000,
localDeletion=1470868106 ]: gateway_time=2016-08-10 22:23+0200 | 
> [133235:35453983:189] Row[info=[ts=-9223372036854775808] del=deletedAt=1470871706530999,
localDeletion=1470871706 ]: gateway_time=2016-08-10 22:23+0200 | 
> [133235:35453983:189] Row[info=[ts=-9223372036854775808] del=deletedAt=1470878906617999,
localDeletion=1470878906 ]: gateway_time=2016-08-10 22:23+0200 | , [humidity[0]=51.0 ts=1470878906618000],
, [temperature[0]=24.378906 ts=1470878906618000]
> {code}
> From my understanding this should be impossible. Even if we have duplicates in the sstables
(which is normal) it should be filtered away before being returned to the client.
> I'm happy to add details to this bug if anything is missing.



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