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From DuyHai Doan <doanduy...@gmail.com>
Subject Re: Adding large text blob causes read timeout...
Date Tue, 24 Jun 2014 06:32:57 GMT
Yes but adding the extra one ends up by * 1000. The limit in CQL3 specifies
the number of logical rows, not the number of physical columns in the
storage engine
Le 24 juin 2014 08:30, "Kevin Burton" <burton@spinn3r.com> a écrit :

> oh.. the difference between the the ONE field and the remaining 29 is
> massive.
>
> It's like 200ms for just the 29 columns.. adding the extra one cause it to
> timeout .. > 5000ms...
>
>
> On Mon, Jun 23, 2014 at 10:30 PM, DuyHai Doan <doanduyhai@gmail.com>
> wrote:
>
>> Don't forget that when you do the Select with limit set to 1000,
>> Cassandra is actually fetching 1000 * 29 physical columns (29 fields per
>> logical row).
>>
>> Adding one extra big html column may be too much and cause timeout. Try
>> to:
>>
>> 1. Select only the big html only
>> 2. Or reduce the limit incrementally until no timeout
>> Le 24 juin 2014 06:22, "Kevin Burton" <burton@spinn3r.com> a écrit :
>>
>> I have a table with a schema mostly of small fields.  About 30 of them.
>>>
>>> The primary key is:
>>>
>>>     primary key( bucket, sequence )
>>>
>>> … I have 100 buckets and the idea is that sequence is ever increasing.
>>>  This way I can read from bucket zero, and everything after sequence N and
>>> get all the writes ordered by time.
>>>
>>> I'm running
>>>
>>> SELECT ... FROM content WHERE bucket=0 AND sequence>0 ORDER BY sequence
>>> ASC LIMIT 1000;
>>>
>>> … using the have driver.
>>>
>>> If I add ALL the fields, except one, so 29 fields, the query is fast.
>>>  Only 129ms….
>>>
>>> However, if I add the 'html' field, which is snapshot of HTML obvious,
>>> the query times out…
>>>
>>> I'm going to add tracing and try to track it down further, but I suspect
>>> I'm doing something stupid.
>>>
>>> Is it going to burn me that the data is UTF8 encoded? I can't image
>>> decoding UTF8 is going to be THAT slow but perhaps cassandra is doing
>>> something silly under the covers?
>>>
>>> cqlsh doesn't time out … it actually works fine but it uses 100% CPU
>>> while writing out the data so it's not a good comparison unfortunately
>>>
>>>
>>> ception in thread "main"
>>> com.datastax.driver.core.exceptions.NoHostAvailableException: All host(s)
>>> tried for query failed (tried: ...:9042
>>> (com.datastax.driver.core.exceptions.DriverException: Timeout during read))
>>>  at
>>> com.datastax.driver.core.exceptions.NoHostAvailableException.copy(NoHostAvailableException.java:65)
>>> at
>>> com.datastax.driver.core.DefaultResultSetFuture.extractCauseFromExecutionException(DefaultResultSetFuture.java:256)
>>>  at
>>> com.datastax.driver.core.DefaultResultSetFuture.getUninterruptibly(DefaultResultSetFuture.java:172)
>>> at
>>> com.datastax.driver.core.SessionManager.execute(SessionManager.java:92)
>>>  at
>>> com.spinn3r.artemis.robot.console.BenchmarkContentStream.main(BenchmarkContentStream.java:100)
>>> Caused by: com.datastax.driver.core.exceptions.NoHostAvailableException:
>>> All host(s) tried for query failed (tried:
>>> dev4.wdc.sl.spinn3r.com/10.24.23.94:9042
>>> (com.datastax.driver.core.exceptions.DriverException: Timeout during read))
>>>  at
>>> com.datastax.driver.core.RequestHandler.sendRequest(RequestHandler.java:103)
>>> at com.datastax.driver.core.RequestHandler$1.run(RequestHandler.java:175)
>>>  at
>>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>>> at
>>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>>>  at java.lang.Thread.run(Thread.java:724)
>>>
>>>
>>> --
>>>
>>> Founder/CEO Spinn3r.com
>>> Location: *San Francisco, CA*
>>> Skype: *burtonator*
>>> blog: http://burtonator.wordpress.com
>>> … or check out my Google+ profile
>>> <https://plus.google.com/102718274791889610666/posts>
>>> <http://spinn3r.com>
>>> War is peace. Freedom is slavery. Ignorance is strength. Corporations
>>> are people.
>>>
>>>
>
>
> --
>
> Founder/CEO Spinn3r.com
> Location: *San Francisco, CA*
> Skype: *burtonator*
> blog: http://burtonator.wordpress.com
> … or check out my Google+ profile
> <https://plus.google.com/102718274791889610666/posts>
> <http://spinn3r.com>
> War is peace. Freedom is slavery. Ignorance is strength. Corporations are
> people.
>
>

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