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From DuyHai Doan <doanduy...@gmail.com>
Subject Re: Adding large text blob causes read timeout...
Date Tue, 24 Jun 2014 05:30:42 GMT
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
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> <http://spinn3r.com>
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>
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