Mathijs Vogelzang created CASSANDRA-9540:
--------------------------------------------
Summary: Cql query doesn't return right information when using IN
on columns for some keys
Key: CASSANDRA-9540
URL: https://issues.apache.org/jira/browse/CASSANDRA-9540
Project: Cassandra
Issue Type: Bug
Components: API
Environment: Cassandra 2.1.5
Reporter: Mathijs Vogelzang
We are investigating a weird issue where one of our clients doesn't get data on
his dashboard. It seems Cassandra is not returning data for a particular key
("brokenkey" from now on).
Some background:
We have a row where we store a "metadata" column and data in columns
"bucket/0", "bucket/1", "bucket/2", etc. Depending on the date selection of the
UI, we know that we only need to retrieve bucket/0, bucket/0 and bucket/1 etc.
(we always need to retrieve "metadata").
A typical query may look like this (using SELECT column1 to just show what is
returned, normally we would of course do SELECT value):
{{noformat}}
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/workingkey');
blobAsText(column1)
---------------------
bucket/0
metadata
(2 rows)
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/brokenkey');
blobAsText(column1)
---------------------
bucket/0
metadata
(2 rows)
{{/noformat}}
These two queries work as expected, and return the information that we actually
stored.
However, when we "filter" for certain columns, the brokenkey starts behaving
very weird:
{{noformat}}
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/workingkey') and column1 IN
(textAsBlob('metadata'),textAsBlob('bucket/0'),textAsBlob('bucket/1'),textAsBlob('bucket/2'));
blobAsText(column1)
---------------------
bucket/0
metadata
(2 rows)
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/workingkey') and column1 IN
(textAsBlob('metadata'),textAsBlob('bucket/0'),textAsBlob('bucket/1'),textAsBlob('bucket/2'),textAsBlob('asdfasdfasdf'));
blobAsText(column1)
---------------------
bucket/0
metadata
(2 rows)
*** As expected, querying for more information doesn't really matter for the
working key ***
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/brokenkey') and column1 IN
(textAsBlob('metadata'),textAsBlob('bucket/0'),textAsBlob('bucket/1'),textAsBlob('bucket/2'));
blobAsText(column1)
---------------------
bucket/0
(1 rows)
*** Cassandra stops giving us the metadata column when asking for a few more
columns! ***
cqlsh:AppBrain> select blobAsText(column1) from "GroupedSeries" where
key=textAsBlob('install/brokenkey') and column1 IN
(textAsBlob('metadata'),textAsBlob('bucket/0'),textAsBlob('bucket/1'),textAsBlob('bucket/2'),textAsBlob('asdfasdfasdf'));
key | column1 | value
-----+---------+-------
(0 rows)
*** Adding the bogus column name even makes it return nothing from this row
anymore! ***
{{/noformat}}
There are at least two rows that malfunction like this in our table (which is
quite old already and has gone through a bunch of Cassandra upgrades). I've
upgraded our whole cluster to 2.1.5 (we were on 2.1.2 when I discovered this
problem) and compacted, repaired and scrubbed this column family, which hasn't
helped.
Our table structure is:
{{noformat}}
cqlsh:AppBrain> describe table "GroupedSeries";
CREATE TABLE "AppBrain"."GroupedSeries" (
key blob,
column1 blob,
value blob,
PRIMARY KEY (key, column1)
) WITH COMPACT STORAGE
AND CLUSTERING ORDER BY (column1 ASC)
AND caching = '{"keys":"ALL", "rows_per_partition":"NONE"}'
AND comment = ''
AND compaction = {'min_threshold': '4', 'class':
'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
'max_threshold': '32'}
AND compression = {'sstable_compression':
'org.apache.cassandra.io.compress.LZ4Compressor'}
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 = 1.0
AND speculative_retry = 'NONE';
{{/noformat}}
Let me know if I can give more information that may be helpful.
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