[jira] [Comment Edited] (CASSANDRA-11528) Server Crash when select returns more than a few hundred rows

["Mattias W (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-11528?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15460611#comment-15460611 ] 

Mattias W edited comment on CASSANDRA-11528 at 9/3/16 7:41 AM:
---------------------------------------------------------------

I thought the answer was that {{count(*)}} is a very expensive operation memory-wise, since that would explain the behaviour. I have now stopped using {{count(*)}}.  Maybe this is more a faq-issue, even if I really do not like that a stupid client can crash the server just by making an expensive operation.


was (Author: mattiasw2):
I thought the answer was that `count(*)` is a very expensive operation memory-wise, since that would explain the behaviour. I have now stopped using count(*).  Maybe this is more a faq-issue, even if I really do not like that a stupid client can crash the server just by making an expensive operation.

> Server Crash when select returns more than a few hundred rows
> -------------------------------------------------------------
>
>                 Key: CASSANDRA-11528
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-11528
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: windows 7, 8 GB machine
>            Reporter: Mattias W
>             Fix For: 3.x
>
>         Attachments: datastax_ddc_server-stdout.2016-04-07.log
>
>
> While implementing a dump procedure, which did "select * from" from one table at a row, I instantly kill the server. A simple 
> {noformat}select count(*) from {noformat} 
> also kills it. For a while, I thought the size of blobs were the cause
> I also try to only have a unique id as partition key, I was afraid a single partition got too big or so, but that didn't change anything
> It happens every time, both from Java/Clojure and from DevCenter.
> I looked at the logs at C:\Program Files\DataStax-DDC\logs, but the crash is so quick, so nothing is recorded there.
> There is a Java-out-of-memory in the logs, but that isn't from the time of the crash.
> It only happens for one table, it only has 15000 entries, but there are blobs and byte[] stored there, size between 100kb - 4Mb. Total size for that table is about 6.5 GB on disk.
> I made a workaround by doing many small selects instead, each only fetching 100 rows.
> Is there a setting a can set to make the system log more eagerly, in order to at least get a stacktrace or similar, that might help you.
> It is the prun_srv that dies. Restarting the NT service makes Cassandra run again



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)