Hi Vladimir,
In fact I am having difficulty to reproduce this issue by cqlsh.
I was reported this issue by one of our developers and he is using his
client application that uses cassandra java driver 3.0.3. (we're using
DSE5.0.1)
<here is how his application log look like>
app A:
2016-10-11 13:28:23,014 [TRACE] [core.QueryLogger.NORMAL] [cluster1]
[HOST1/IP1:9042] Query completed normally, took 5 ms: [8 bound values]
INSERT INTO global.table_name
("id","alert_to","alert_emails","created_by","created_date","alert_level","updated_by","updated_date")
VALUES (?,?,?,?,?,?,?,?);
[id:25712, alert_to:[2], alert_emails:NULL,
created_by:'service-worker:ec45afd2-c40a-44d9-a2a1-7416409be6e2',
created_date:1476160103007, alert_level:2, updated_by:NULL,
updated_date:NULL]
app B:
2016-10-11 13:28:23,014 [TRACE] [core.QueryLogger.NORMAL] [cluster1]
[HOST2/IP2:9042] Query completed normally, took 6 ms: [8 bound values]
INSERT INTO global.table_name
("alert_to","alert_emails","created_date","id","created_by","updated_by","updated_date","alert_level")
VALUES (?,?,?,?,?,?,?,?);
[alert_to:[1], alert_emails:NULL, created_date:1476160103007,
id:25712, created_by:'service-worker:ec45afd2-c40a-44d9-a2a1-7416409be6e2',
updated_by:NULL, updated_date:NULL, alert_level:1]
<and the data on cassandra>
<TYPES>
id bigint,
alert_emails list,
alert_level int,
alert_to list,
created_by text,
created_date timestamp,
updated_by text,
updated_date timestamp,
PRIMARY KEY (id)
SELECT id, alert_level, alert_to FROM global.table_name WHERE id=25712;
| id | alert_level | alert_to |
| 25712 | 2 | [2, 1] |
but when I threw the queries like below from cqlsh from different
nodes at the same time in my testing environment, the data(alert_to)
was just [1], which is expected behavior.
on host 1
cqlsh> INSERT INTO global.table_name
("id","alert_to","alert_emails","created_by","created_date","alert_level","updated_by","updated_date")
VALUES
(25712,[2],NULL,'service-worker:ec45afd2-c40a-44d9-a2a1-7416409be6e2',1476160103007,2,NULL,NULL);
on host2
cqlsh> INSERT INTO global.table_name
("alert_to","alert_emails","created_date","id","created_by","updated_by","updated_date","alert_level")
VALUES
([1],NULL,1476160103007,25712,'service-worker:ec45afd2-c40a-44d9-a2a1-7416409be6e2',NULL,NULL,1);
so I wonder if this is something wrong with java driver but I cannot
figure out the way to break this down further.
@Andrew
we're not using UDT..but appreciate if you could share your case, too.
Thanks,
Aoi
2016-10-13 11:26 GMT-07:00 Andrew Baker <baker...@gmail.com>:
> I saw evidence of this behavior, but when we created a test to try to make
> it happen it never did, we assumed it was UDT related and lost interest,
> since it didn't have a big impact. I will try to carve some time to look
> into this some more and let you know if I find anything.
>
> On Wed, Oct 12, 2016 at 9:24 PM Vladimir Yudovin <vla...@winguzone.com>
> wrote:
>>
>> The data is actually appended. not overwritten.
>> Strange, can you send exactly operators?
>>
>> Here is example I do:
>> CREATE KEYSPACE events WITH replication = {'class': 'SimpleStrategy',
>> 'replication_factor': 1};
>> CREATE TABLE events.data (id int primary key, events list<text>);
>> INSERT INTO events.data (id, events) VALUES ( 0, ['a']);
>> SELECT * FROM events.data ;
>> id | events
>> ----+--------
>> 0 | ['a']
>>
>> (1 rows)
>>
>> INSERT INTO events.data (id, events) VALUES ( 0, ['b']);
>> SELECT * FROM events.data ;
>> id | events
>> ----+--------
>> 0 | ['b']
>>
>> (1 rows)
>>
>> As you see, 'a' was overwritten by 'b'
>>
>>
>> Best regards, Vladimir Yudovin,
>> Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
>> Launch your cluster in minutes.
>>
>>
>> ---- On Wed, 12 Oct 2016 23:58:23 -0400Aoi Kadoya <cadyan....@gmail.com>
>> wrote ----
>>
>> yes, that's what I thought. but, when I use these forms,
>> INSERT ... ['A']
>> INSERT ... ['B']
>>
>> The data is actually appended. not overwritten.
>> so I guess this is something unexpected?
>>
>> Thanks,
>> Aoi
>>
>> 2016-10-12 20:55 GMT-07:00 Vladimir Yudovin <vla...@winguzone.com>:
>> > If you use form
>> > INSERT ... ['A']
>> > INSERT ... ['B']
>> >
>> > latest INSERT will overwrite first, because this insert the whole list.
>> > It's
>> > better to use UPDATE like:
>> > UPDATE ... SET events = events + ['A']
>> > UPDATE ... SET events = events + ['B']
>> > These operations add new elements to the end of existing list.
>> >
>> >
>> > From here
>> > https://docs.datastax.com/en/cql/3.0/cql/cql_using/use_list_t.html
>> > :
>> >
>> > These update operations are implemented internally without any
>> > read-before-write. Appending and prepending a new element to the list
>> > writes
>> > only the new element.
>> >
>> >
>> > Best regards, Vladimir Yudovin,
>> > Winguzone - Hosted Cloud Cassandra on Azure and SoftLayer.
>> > Launch your cluster in minutes.
>> >
>> >
>> > ---- On Wed, 12 Oct 2016 17:39:46 -0400Aoi Kadoya <cadyan....@gmail.com>
>> > wrote ----
>> >
>> > Hi,
>> >
>> > When inserting different data into a list type column from different
>> > clients at the same time, is data supposed to be combined into one
>> > list?
>> >
>> > For example, if these 2 queries were requested from clients at the
>> > same timing, how events list should look like after?
>> >
>> > INSERT INTO cycling.upcoming_calendar (year, month, events) VALUES
>> > (2015, 06, ['A']);
>> > INSERT INTO cycling.upcoming_calendar (year, month, events) VALUES
>> > (2015, 06, ['B']);
>> >
>> > In my understanding, each operation should be treated as atomic, which
>> > makes me think that even if client throw the queries at the same time,
>> > cassandra would take them separately and the last insert would update
>> > the events list. (= data should be either ['A'] or ['B'])
>> >
>> > In my environment, I found that some data was saved as like ['A',B']
>> > in the case like above.
>> > Is this expected behavior of list data type?
>> >
>> > I am still new to cassandra and trying to make myself understood how
>> > this happened.
>> > Appreciate if you could help me with figuring this out!
>> >
>> > Thanks,
>> > Aoi
>> >
>> >
