> Does anyone have any intuition about whether this will happen with
> consistency_level=ALL? I will try it today, but I'd like to know what the
> expected behavior is. It seems like it would not happen in this case.
Assuming my understanding is correct (see my comment in the JIRA
ticket), then
That's what I thought was happening, yes. A careful reading of the
documentation suggests that this is correct behavior.
Tyler says this can also occur because of a TimedOutException on the writes.
This worries me because TimedOutExceptions are so frequent (at least for my
test cluster), ther
James: I feel like I understand what's going on in your code now based on
this discussion, and I'm ok with the fact that DURING a QW you can get
"transitional" results from a QR in another process (or either the before or
after state of the QW). But once the QW succeeds, you must get the new
value
Same process or not: only successful QR reads after successful QW will
behave with this guarantee.
/***
sent from my android...please pardon occasional typos as I respond @ the
speed of thought
/
On Apr 17, 2011 10:04 AM, "James Cipar" wrote:
> For a
> For a second, I thought this thread was saying I could see value(s) < new
> value(s) within the same process on the second read at quorum
That's exactly what I'm saying. Within a single process I see this behavior,
when reading with consistency_level=QUORUM
Read value 1
Read value 2
Read val
Cool, that is exactly what I was thinking/expecting, and I feel better about
the assumptions I've used in my refactor to move from MySQL -> cassandra.
I basically gave up on trying to force my code to assume (even at quorum):
-read value(s) for key from cassandra
-update/add/delete columns for key
William
The issue is regarding whether you will see A or B; with any guarantee of
either. The discussion implies no; until the QW is complete.
/***
sent from my android...please pardon occasional typos as I respond @ the
speed of thought
/
On Apr 17, 20
Successful reads after a successful write @Q have the property of once the
read is seen @ one Q, the same read will be seen at any other Q.
All others are details that will change with implementation; but,imo, are
not bugs.
James: in your case, I would think that you have not completed a successf
>> target_server = '%s:9160'%target_server
> >>> try:
> >>> pool = pycassa.connect('Keyspace1', [target_server])
> >>> cf = pycassa.ColumnFamily(pool, 'Standard1')
> >>>
timestamp = 0
>>>>> while time.time() < start_time + duration:
>>>>> target_server = random.sample(servers, 1)[0]
>>>>> target_server = '%s:9160'%target_server
>>>>> try:
>>>>>
for line in f:
>> >>> servers.append(line.strip())
>> >>> f.close()
>> >>> return servers
>> >>> servers = read_servers(hostlist)
>> >>> start_time = time.time()
>> >>> seqnum
= random.sample(servers, 1)[0]
>>>> target_server = '%s:9160'%target_server
>>>> try:
>>>> pool = pycassa.connect('Keyspace1', [target_server])
>>>> cf = pycassa.ColumnFamily(pool, 'Standa
t;>> target_server = '%s:9160'%target_server
> >>> try:
> >>> pool = pycassa.connect('Keyspace1', [target_server])
> >>> cf = pycassa.ColumnFamily(pool, 'Standard1')
> >>>
s:9160'%target_server
> >>> try:
> >>> pool = pycassa.connect('Keyspace1', [target_server])
> >>> cf = pycassa.ColumnFamily(pool, 'Standard1')
> >>> row = cf.get('foo',
>
arget_server])
>>> cf = pycassa.ColumnFamily(pool, 'Standard1')
>>> row = cf.get('foo', read_consistency_level=consistency_level)
>>> pool.dispose()
>>> except:
>>> time.sleep(slee
t;> time.sleep(sleeptime)
>> continue
>> sq = int(row['seqnum'])
>> ts = float(row['timestamp'])
>> if sq < seqnum:
>> print 'Row changed: %i %f -> %i %f'%(seqnum,
if sq < seqnum:
> print 'Row changed: %i %f -> %i %f'%(seqnum, timestamp, sq, ts)
> seqnum = sq
> timestamp = ts
>
> if sleeptime > 0.0:
> time.sleep(sleeptime)
>
>
>
>
> On Apr 16, 2011, at
M, Tyler Hobbs wrote:
> James,
>
> Would you mind sharing your reader process code as well?
>
> On Fri, Apr 15, 2011 at 1:14 PM, James Cipar wrote:
> I've been experimenting with the consistency model of Cassandra, and I found
> something that seems a bit unexpected.
James,
Would you mind sharing your reader process code as well?
On Fri, Apr 15, 2011 at 1:14 PM, James Cipar wrote:
> I've been experimenting with the consistency model of Cassandra, and I
> found something that seems a bit unexpected. In my experiment, I have 2
> processes,
ailed (which should be reported to your
> code via an exception).
>
> Dan
>
> -Original Message-
> From: James Cipar [mailto:jci...@cmu.edu]
> Sent: April-15-11 14:15
> To: user@cassandra.apache.org
> Subject: Consistency model
>
> I've been experimenting with
your
code via an exception).
Dan
-Original Message-
From: James Cipar [mailto:jci...@cmu.edu]
Sent: April-15-11 14:15
To: user@cassandra.apache.org
Subject: Consistency model
I've been experimenting with the consistency model of Cassandra, and I found
something that seems
I've been experimenting with the consistency model of Cassandra, and I found
something that seems a bit unexpected. In my experiment, I have 2 processes, a
reader and a writer, each accessing a Cassandra cluster with a replication
factor greater than 1. In addition, sometimes I gen
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