6 Jun
2016
6 Jun
'16
9:37 p.m.
On 06/06/16 21:10, Nikita Salnikov-Tarnovski wrote:
>> On 06 Jun 2016, at 21:36, Martin Kersten <martin@monetdb.org <mailto:martin@monetdb.org>> wrote:
>>
>> Hi
>>
>> Please provide information on which MonetDB release and platform you are using.
>
> Ou, sorry for forgetting this. This is Ubuntu, 14.04.3 LTS.
>
> uname -a
> Linux ip-10-0-0-47 3.13.0-74-generic #118-Ubuntu SMP Thu Dec 17 22:52:10 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
>
> MonetDB version, as I said:
>
> 2016-06-06 19:05:27 MSG merovingian[1255]: Merovingian 1.7 (Jul2015-SP4) starting
> 2016-06-06 19:05:27 MSG merovingian[1255]: monitoring dbfarm /mnt/mysql-copy
> 2016-06-06 19:05:27 MSG merovingian[1255]: accepting connections on TCP socket 0.0.0.0:50000
> 2016-06-06 19:05:27 MSG merovingian[1255]: accepting connections on UNIX domain socket /tmp/.s.monetdb.50000
> 2016-06-06 19:05:27 MSG discovery[1255]: listening for UDP messages on 0.0.0.0:50000
> 2016-06-06 19:05:27 MSG control[1255]: accepting connections on UNIX domain socket /tmp/.s.merovingian.50000
> 2016-06-06 19:05:27 MSG discovery[1255]: new neighbour ip-10-0-0-47 (ip-10-0-0-47.eu <http://ip-10-0-0-47.eu>-west-1.compute.internal)
> 2016-06-06 19:05:29 MSG discovery[1255]: new database mapi:monetdb://ip-10-0-0-47:50000/mysql-copy (ttl=660s)
> 2016-06-06 19:05:44 MSG merovingian[1255]: starting database 'mysql-copy', up min/avg/max: 5m/8h/22h, crash average: 1.00 0.90 0.97 (126-4=122)
> 2016-06-06 19:05:45 MSG mysql-copy[1263]: arguments: /usr/bin/mserver5 --dbpath=/mnt/mysql-copy/mysql-copy --set merovingian_uri=mapi:monetdb://ip-10-0-0-47:50000/mysql-copy --set mapi_open=false --set mapi_port=0 --set
> mapi_usock=/mnt/mysql-copy/mysql-copy/.mapi.sock --set monet_vault_key=/mnt/mysql-copy/mysql-copy/.vaultkey --set gdk_nr_threads=4 --set max_clients=64 --set sql_optimizer=default_pipe --set monet_daemon=yes
> 2016-06-06 19:05:45 MSG mysql-copy[1263]: # MonetDB 5 server v11.21.19 "Jul2015-SP4"
> 2016-06-06 19:05:45 MSG mysql-copy[1263]: # Serving database 'mysql-copy', using 4 threads
> 2016-06-06 19:05:45 MSG mysql-copy[1263]: # Compiled for x86_64-pc-linux-gnu/64bit with 64bit OIDs and 128bit integers dynamically linked
> 2016-06-06 19:05:45 MSG mysql-copy[1263]: # Found 15.672 GiB available main-memory.
>
>>
>> Overall, the symptoms provided do not ring a bell on a possible problem.
>>
>> Assuming you were able to create this database, it might by a good idea to trim down
>> the problem by growing the database in a few steps to isolate if size is the problem.
>
> Are there any known limits of tables sizes? Row-wise or size-wise?
There are no limits, except for your diskspace.
>
>> You also could check the system logs and/or merovingian.log of your instance to determine
>> if the DBMS received an OOM kill signal from the OS.
>
> merovingan.log:
> 2016-06-06 19:05:53 MSG merovingian[1255]: database 'mysql-copy' (1263) was killed by signal SIGSEGV
>
> dmesg:
> [ 310.163434] mserver5[1268]: segfault at 0 ip 00007f19deb63712 sp 00007f19ddc12a80 error 4 in lib_sql.so[7f19deb35000+199000]
>
> No mentions of oom_killer.
>
>>
>> The last resort is to attach a debugger to the server before you issue the query to catch
>> a stack trace where it happens in the code base.
>
> Do you have any how-to doc for that?
roughly:
1) start mserver5 using the latest arguments line you can find in the merovingian.log file
2) in a separate window locate the process id of that mserver5 instance
3) attach the debugger:
gdb mserver5 <processId>
continue
4) use mclient to connect to the server and run the query
If it segfaults you can see it in the window 2)
issue a backtrace/bt/where command to find the stack trace.
regards, Martin
>
> Thank you for your help,
>
> Nikita
>
>>
>> regards, Martin
>>
>>
>> On 06/06/16 18:13, Nikita Salnikov-Tarnovski wrote:
>>> Hello. I am evaluating MonetDB to use in our project, but so far have some real problems with MonetDB constantly having segmentation faults. Here is my setup:
>>>
>>> I am using AWS EC2 instance with 16GB of RAM, monetdb farm is location on ESB volume.
>>>
>>> Welcome to mclient, the MonetDB/SQL interactive terminal (Jul2015-SP4)
>>> Database: MonetDB v11.21.19 (Jul2015-SP4), 'mapi:monetdb://ip-10-0-0-47:50000/mysql-copy'
>>>
>>> In there I have several tables, among them is one table I am most interested in, problemsview, with total columnsize of 120GB, largest column is around 11GB.
>>>
>>> The moment I execute “select count(1) from problemsview;” I get segmentation fault:
>>>
>>> mserver5[1300]: segfault at 0 ip 00007f86a0ca0712 sp 00007f869b6faa80 error 4 in lib_sql.so[7f86a0c72000+199000]
>>>
>>> Next
>>> select * from problemsview limit 10;
>>>
>>> wait for 20-30 seconds, and then segmentation fault:
>>> mserver5[1313]: segfault at 18 ip 00007f68cf2a0726 sp 00007f68ce14ea80 error 4 in lib_sql.so[7f68cf272000+199000]
>>>
>>> So essentially I cannot do anything, I always get segmentation fault. Can this be fixed somehow?
>>>
>>> Thank you in advance,
>>>
>>> Nikita Salnikov-Tarnovski
>>> Plumbr Founder and Master Developer
>>> @JavaPlumbr/@iNikem
>>>
>>>
>>>
>>> _______________________________________________
>>> users-list mailing list
>>> users-list@monetdb.org <mailto:users-list@monetdb.org>
>>> https://www.monetdb.org/mailman/listinfo/users-list
>>>
>>
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