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From Gabriel Ciuloaica <gciuloa...@gmail.com>
Subject Trying to identify the problem with CQL ...
Date Tue, 05 Mar 2013 10:24:17 GMT
Hello,

I'm trying to find out what the problem is and where it is located.
I have a 3 nodes Cassandra cluster (1.2.1), RF=3.
I have a keyspace and a cf as defined (using PropertyFileSnitch):

CREATE KEYSPACE backend WITH replication = {
   'class': 'NetworkTopologyStrategy',
   'DC-TORONTO': '3'
};

USE backend;

CREATE TABLE avatars (
   id bigint PRIMARY KEY,
   avatar blob,
   image_type text
) WITH
   bloom_filter_fp_chance=0.010000 AND
   caching='KEYS_ONLY' AND
   comment='' AND
   dclocal_read_repair_chance=0.000000 AND
   gc_grace_seconds=864000 AND
   read_repair_chance=0.100000 AND
   replicate_on_write='true' AND
   compaction={'class': 'SizeTieredCompactionStrategy'} AND
   compression={'sstable_compression': 'SnappyCompressor'};

Status of the cluster:
Datacenter: DC-TORONTO
======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address           Load       Tokens  Owns   Host 
ID                               Rack
UN  10.11.1.109       44.98 MB   256     46.8% 
726689df-edc3-49a0-b680-370953994a8c  RAC2
UN  10.11.1.200       6.57 MB    64      10.3% 
d6d700d4-28aa-4722-b215-a6a7d304b8e7  RAC3
UN  10.11.1.108       54.32 MB   256     42.8% 
73cd86a9-4efb-4407-9fe8-9a1b3a277af7  RAC1

I'm trying to read my writes, by using CQL (datastax-java-driver), using 
LOCAL_QUORUM for reads and writes. For some reason, some of the writes 
are lost. Not sure if it is a driver issue or cassandra issue.
Dinging further, using cqlsh client (1.2.1), I found a strange situation:

select count(*) from avatars;

  count
-------
    226

select id from avatars;

  id
---------
      314
      396
       19
  .........    ->  77 rows in result

select id, image_type from avatars;

  id      | image_type
---------+------------
      332 |        png
      314 |        png
      396 |       jpeg
       19 |        png
  1250014 |       jpeg
........ -> 226 rows in result.

I do not understand why for second select I'm able to retrieve just a 
part of the rows and not all rows.

Not sure if this is related or not to the initial problem.

Any help is really appreciated.
Thanks,
Gabi





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