Unexpected rows in MV after upgrading to 3.0.15

[Tom van der Woerdt <to...@booking.com>]

Hello,

While testing 3.0.15, we noticed that some materialized views started
showing rows that shouldn't exist, as multiple rows in the view map to a
single row in the base table.

I've pasted the table structure below, but essentially there's a base table
"((pk1,pk2,pk3),ck1),col1" and MV "((pk1,pk2,pk3),col1,ck1)". This means
that if col1 changes, we expect a delete and insert on the MV. And yet this
happens:

> select col1, ck1, dateof(col1) FROM view_1 where pk1='abc' and pk2='123'
and pk3='def';

 col1                                 |
ck1                                  | system.dateof(col1)
--------------------------------------+--------------------------------------+---------------------------------
 7bd437d9-bccc-11e7-9748-40749b41c1e0 |
295eae9b-d544-4064-8dbc-0c56772759f3 | 2017-10-29 17:13:29.494000+0000
 df39e364-bed3-11e7-8a3d-953c29bf01ff |
295eae9b-d544-4064-8dbc-0c56772759f3 | 2017-11-01 07:11:25.057000+0000
 928980ae-bed5-11e7-8b41-6e709b16923d |
295eae9b-d544-4064-8dbc-0c56772759f3 | 2017-11-01 07:23:35.388000+0000
 # Only relevant rows are shown

> select col1,writetime(col1),dateof(col1) from table_1 where pk1='abc' and
pk2='123' and pk3='def' and ck1='295eae9b-d544-4064-8dbc-0c56772759f3';

 col1                                 | writetime(col1)         |
system.dateof(col1)
--------------------------------------+-------------------------+---------------------------------
 928980ae-bed5-11e7-8b41-6e709b16923d |        1509728864328000 |
2017-11-01 07:23:35.388000+0000

It's not supposed to be possible, and yet there are three rows that all map
onto the same primary key in the base table.

The cluster was upgraded on 2017-10-31, so the first row could *maybe* be
explained by CASSANDRA-11500, but the second row can't. The third row is
the one we expect to be there.

Is this a new regression in 3.0.15? Is anyone else experiencing this, or
should I file a ticket?

Thanks,
Tom


------- Full structure: ---------

CREATE TABLE the_keyspace.table_1 (
    pk1 ascii,
    pk2 ascii,
    pk3 ascii,
    ck1 ascii,
    col1 timeuuid,
    PRIMARY KEY ((pk1, pk2, pk3), ck1)
) WITH CLUSTERING ORDER BY (ck1 ASC)
    AND bloom_filter_fp_chance = 0.1
    AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'}
    AND comment = ''
    AND compaction = {'class':
'org.apache.cassandra.db.compaction.LeveledCompactionStrategy'}
    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';

CREATE MATERIALIZED VIEW the_keyspace.view_1 AS
    SELECT *
    FROM the_keyspace.table_1
    WHERE pk1 IS NOT NULL AND pk2 IS NOT NULL AND pk3 IS NOT NULL AND col1
IS NOT NULL AND ck1 IS NOT NULL
    PRIMARY KEY ((pk1, pk2, pk3), col1, ck1)
    WITH CLUSTERING ORDER BY (col1 ASC, ck1 ASC)
    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.LeveledCompactionStrategy'}
    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';


Tom van der Woerdt
Site Reliability Engineer

Booking.com B.V.
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