[CASSANDRA-11679] Cassandra Driver returns different number of results depending on fetchsize

• Type: Bug
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 2.1.15
• Component/s: Legacy/CQL
• Severity: Normal
• Assignee: Benjamin Lerer
• Reporter: Varun Barala

Authors

Benjamin Lerer

Reviewers

Tom Hobbs

• Created: 28/Apr/16 07:34
• Updated: 16/Apr/19 09:30
• Resolved: 13/May/16 19:24

Description

I'm trying to fetch all distinct keys from a CF using cassandra-driver (2.1.7.1) and I observed some strange behavior :-

The total distinct rows are 498 so If I perform a query get All distinctKeys It returns 503 instead of 498(five keys twice).
But If I define the fetch size in select statement more than 498 then it returns exact 498 rows.

And If I execute same statement on Dev-center it returns 498 rows (because the default fetch size is 5000). In `cqlsh` it returns 503 rows (because cqlsh uses fetch size=100).

Some Additional and useful information :-
-------------------------------------------------------
Cassandra-2.1.13 (C)* version
Consistency level: ONE
local machine(ubuntu 14.04)

Table Schema:-
----------------------

CREATE TABLE sample (
     pk1 text,
     pk2 text,
    row_id uuid,
    value blob,
    PRIMARY KEY (( pk1,  pk2))
) WITH 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'}
    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 = 0.0
    AND speculative_retry = '99.0PERCENTILE';

query :-
------------

SELECT DISTINCT  pk2, pk1 FROM sample LIMIT 2147483647;