Andreas Wederbrand created CASSANDRA-12756:
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Summary: 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
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';
and the result from the SELECT is
> 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}
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.
[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]
>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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