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From Alexander Shutyaev <shuty...@gmail.com>
Subject Re: DELETE does not delete :)
Date Wed, 16 Oct 2013 05:12:38 GMT
Hi all,

Unfortunately, we still have a problem. I've modified my code, so that it
explicitly sets the consistency level to *QUORUM* for each query. However,
we found out a few cases when the record is deleted on only *1 node of 3*.
In this cases the *delete* query executed ok, and the *select* query that
we do right after delete returned *0* rows. Later when we ran a global
daily check *select* returned *1* row. How can that be? What can we be
missing?


2013/10/7 Jon Haddad <jon@jonhaddad.com>

> I haven't used VMWare but it seems odd that it would lock up the ntp port.
>  try "ps aux | grep ntp" to see if ntpd it's already running.
>
> On Oct 7, 2013, at 12:23 AM, Alexander Shutyaev <shutyaev@gmail.com>
> wrote:
>
> Hi MichaƂ,
>
> I didn't notice your message at first.. Well this seems like a real cause
> candidate.. I'll add an explicit consistency level QUORUM and see if that
> helps. Thanks
>
>
> 2013/10/7 Alexander Shutyaev <shutyaev@gmail.com>
>
>> Hi Nick,
>>
>> Thanks for the note! We have our cassanra instances installed on virtual
>> hosts in VMWare and the clock synchronization is handled by the latter, so
>> I can't use ntpdate (says that NTP socket is in use). Is there any way to
>> check if the clocks are really synchronized? My best attempt was using
>> three shell windows with commands already typed thus requiring only
>> clicking on the window and hitting enter. The results varied by 100-200
>> msec which I guess is just about the time I need to click and press enter :)
>>
>> Thanks in advance,
>> Alexander
>>
>>
>> 2013/10/7 Nikolay Mihaylov <nmmm@nmmm.nu>
>>
>>> Hi
>>>
>>> my two cents - before doing anything else, make sure clocks are
>>> synchronized to the millisecond.
>>> ntp will do so.
>>>
>>> Nick.
>>>
>>>
>>> On Mon, Oct 7, 2013 at 9:02 AM, Alexander Shutyaev <shutyaev@gmail.com>wrote:
>>>
>>>> Hi all,
>>>>
>>>> We have encountered the following problem with cassandra.
>>>>
>>>> * We use *cassandra v2.0.0* from *Datastax* community repo.
>>>>
>>>> * We have *3 nodes* in a cluster, all of them are seed providers.
>>>>
>>>> * We have a *single keyspace* with *replication factor = 3*:
>>>>
>>>> *CREATE KEYSPACE bof WITH replication = {*
>>>> *  'class': 'SimpleStrategy',*
>>>> *  'replication_factor': '3'*
>>>> *};*
>>>>
>>>> * We use *Datastax Java CQL Driver v1.0.3* in our application.
>>>>
>>>> * We have not modified any *consistency settings* in our app, so I
>>>> assume we have the *default QUORUM* (2 out of 3 in our case)
>>>> consistency *for reads and writes*.
>>>>
>>>> * We have 400+ tables which can be divided in two groups (*main* and *
>>>> uids*). All tables in a group have the same definition, they vary only
>>>> by name. The sample definitions are:
>>>>
>>>> *CREATE TABLE bookingfile (*
>>>> *  key text,*
>>>> *  entity_created timestamp,*
>>>> *  entity_createdby text,*
>>>> *  entity_entitytype text,*
>>>> *  entity_modified timestamp,*
>>>> *  entity_modifiedby text,*
>>>> *  entity_status text,*
>>>> *  entity_uid text,*
>>>> *  entity_updatepolicy text,*
>>>> *  version_created timestamp,*
>>>> *  version_createdby text,*
>>>> *  version_data blob,*
>>>> *  version_dataformat text,*
>>>> *  version_datasource text,*
>>>> *  version_modified timestamp,*
>>>> *  version_modifiedby text,*
>>>> *  version_uid text,*
>>>> *  version_versionnotes text,*
>>>> *  version_versionnumber int,*
>>>> *  versionscount int,*
>>>> *  PRIMARY KEY (key)*
>>>> *) 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*
>>>> *  index_interval=128 AND*
>>>> *  read_repair_chance=0.100000 AND*
>>>> *  replicate_on_write='true' AND*
>>>> *  populate_io_cache_on_flush='false' AND*
>>>> *  default_time_to_live=0 AND*
>>>> *  speculative_retry='NONE' AND*
>>>> *  memtable_flush_period_in_ms=0 AND*
>>>> *  compaction={'class': 'SizeTieredCompactionStrategy'} AND*
>>>> *  compression={'sstable_compression': 'LZ4Compressor'};*
>>>>
>>>> *CREATE TABLE bookingfile_uids (*
>>>> *  date text,*
>>>> *  timeanduid text,*
>>>> *  deleted boolean,*
>>>> *  PRIMARY KEY (date, timeanduid)*
>>>> *) 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*
>>>> *  index_interval=128 AND*
>>>> *  read_repair_chance=0.100000 AND*
>>>> *  replicate_on_write='true' AND*
>>>> *  populate_io_cache_on_flush='false' AND*
>>>> *  default_time_to_live=0 AND*
>>>> *  speculative_retry='NONE' AND*
>>>> *  memtable_flush_period_in_ms=0 AND*
>>>> *  compaction={'class': 'SizeTieredCompactionStrategy'} AND*
>>>> *  compression={'sstable_compression': 'LZ4Compressor'};*
>>>> *
>>>> *
>>>> *CREATE INDEX BookingFile_uids_deleted ON bookingfile_uids (deleted);*
>>>>
>>>> * We don't have any problems with the tables from the *main* group.
>>>>
>>>> * As for the tables from the *uids* group we have noticed that
>>>> sometimes deletes from these tables do not do their job. They don't fail,
>>>> they just do nothing. We have confirmed this by adding a select query after
>>>> deletes. Most times everything is ok and select returns 0 records. But
>>>> sometimes (~5 out of 100,000) it returns the supposedly deleted row.
>>>>
>>>> * We have logged the ExecutionInfo objects with query tracing that are
>>>> returned by Datastax's driver. Here are the details
>>>>
>>>> *DELETE FROM bookingfile_uids WHERE date=C20131006 AND
>>>> timeAndUid=195248590_4762ce41-d2d2-448d-be8c-c7fcb6b7394e*
>>>>
>>>> *ExecutionInfo: [*
>>>> *triedHosts=/10.10.30.23;*
>>>> *queriedHost=/10.10.30.23;*
>>>>  *achievedConsistencyLevel=null;*
>>>> *queryTrace=*
>>>> * Message received from /10.10.30.23 on /10.10.30.19[Thread-56] at Sun
>>>> Oct 06 19:55:57 MSK 2013*
>>>> * Acquiring switchLock read lock on /10.10.30.19[MutationStage:49] at
>>>> Sun Oct 06 19:55:57 MSK 2013*
>>>> * Appending to commitlog on /10.10.30.19[MutationStage:49] at Sun Oct
>>>> 06 19:55:57 MSK 2013*
>>>> * Adding to bookingfile_uids memtable on /10.10.30.19[MutationStage:49]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Enqueuing response to /10.10.30.23 on /10.10.30.19[MutationStage:49]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Sending message to /10.10.30.23 on /10.10.30.19[WRITE-/10.10.30.23]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Message received from /10.10.30.23 on /10.10.30.20[Thread-34] at Sun
>>>> Oct 06 19:55:57 MSK 2013*
>>>> * Acquiring switchLock read lock on /10.10.30.20[MutationStage:43] at
>>>> Sun Oct 06 19:55:57 MSK 2013*
>>>> * Appending to commitlog on /10.10.30.20[MutationStage:43] at Sun Oct
>>>> 06 19:55:57 MSK 2013*
>>>> * Adding to bookingfile_uids memtable on /10.10.30.20[MutationStage:43]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Enqueuing response to /10.10.30.23 on /10.10.30.20[MutationStage:43]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Sending message to /10.10.30.23 on /10.10.30.20[WRITE-/10.10.30.23]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Determining replicas for mutation on /10.10.30.23[Native-Transport-Requests:1387368]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Sending message to /10.10.30.19 on /10.10.30.23[WRITE-/10.10.30.19]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Acquiring switchLock read lock on /10.10.30.23[MutationStage:46] at
>>>> Sun Oct 06 19:55:57 MSK 2013*
>>>> * Sending message to /10.10.30.20 on /10.10.30.23[WRITE-/10.10.30.20]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Message received from /10.10.30.20 on /10.10.30.23[Thread-5] at Sun
>>>> Oct 06 19:55:57 MSK 2013*
>>>> * Processing response from /10.10.30.20 on /10.10.30.23[RequestResponseStage:4]
>>>> at Sun Oct 06 19:55:57 MSK 2013*
>>>> * Message received from /10.10.30.19 on /10.10.30.23[Thread-7] at Sun
>>>> Oct 06 19:55:57 MSK 2013*
>>>> * Processing response from /10.10.30.19 on /10.10.30.23[RequestResponseStage:4]
>>>> at Sun Oct 06 19:55:57 MSK 2013;*
>>>> *]*
>>>>
>>>> *SELECT * FROM bookingfile_uids WHERE date=C20131006 AND
>>>> timeAndUid=195248590_4762ce41-d2d2-448d-be8c-c7fcb6b7394e returned 1 record
>>>> *
>>>>
>>>> the same query 1 second later:
>>>>
>>>> *DELETE FROM bookingfile_uids WHERE date=C20131006 AND
>>>> timeAndUid=195248590_4762ce41-d2d2-448d-be8c-c7fcb6b7394e*
>>>> *
>>>> *
>>>> *ExecutionInfo: [*
>>>> *triedHosts=/10.10.30.20;*
>>>> *queriedHost=/10.10.30.20;*
>>>> *achievedConsistencyLevel=null;*
>>>> *queryTrace=*
>>>> * Message received from /10.10.30.20 on /10.10.30.19[Thread-57] at Sun
>>>> Oct 06 19:55:58 MSK 2013*
>>>> * Determining replicas for mutation on /10.10.30.20[Native-Transport-Requests:1387705]
>>>> at Sun Oct 06 19:55:58 MSK 2013*
>>>> * Acquiring switchLock read lock on /10.10.30.20[MutationStage:43] at
>>>> Sun Oct 06 19:55:58 MSK 2013*
>>>> * Appending to commitlog on /10.10.30.20[MutationStage:43] at Sun Oct
>>>> 06 19:55:58 MSK 2013*
>>>> * Adding to bookingfile_uids memtable on /10.10.30.20[MutationStage:43]
>>>> at Sun Oct 06 19:55:58 MSK 2013*
>>>> * Sending message to /10.10.30.19 on /10.10.30.20[WRITE-/10.10.30.19]
>>>> at Sun Oct 06 19:55:58 MSK 2013*
>>>> * Sending message to /10.10.30.23 on /10.10.30.20[WRITE-/10.10.30.23]
>>>> at Sun Oct 06 19:55:58 MSK 2013*
>>>> * Message received from /10.10.30.19 on /10.10.30.20[Thread-4] at Sun
>>>> Oct 06 19:55:58 MSK 2013*
>>>> * Processing response from /10.10.30.19 on /10.10.30.20[RequestResponseStage:6]
>>>> at Sun Oct 06 19:55:58 MSK 2013*
>>>> * Message received from /10.10.30.20 on /10.10.30.23[Thread-18] at Sun
>>>> Oct 06 19:55:58 MSK 2013*
>>>> *]*
>>>> *
>>>> *
>>>> *SELECT * FROM bookingfile_uids WHERE date=C20131006 AND
>>>> timeAndUid=195248590_4762ce41-d2d2-448d-be8c-c7fcb6b7394e returned 0
>>>> records.*
>>>>
>>>> * Cassandra's system.log on all 3 nodes lists nothing special during
>>>> these queries - just some compaction related *INFO* entries.
>>>>
>>>> Can anyone help with this? What is our next step?
>>>>
>>>> Thanks in advance,
>>>> Alexander
>>>>
>>>
>>>
>>
>
>

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