Details
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Type:
Bug
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Status: Closed
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Priority:
Major
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Resolution: Duplicate
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Affects Version/s: 10.0.8
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Fix Version/s: None
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Component/s: None
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Labels:
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Environment:Debian Wheezy
MariaDB 10.0.8 (query cache disabled)
Description
This does not happen every time, unfortunately. I've tried to google this issue - 've found similar problems, but most of them revolve around MariaDB 5 series with OQGRAPH v2, not v3.
Create a test database with the information listed here:
https://mariadb.com/kb/en/oqgraph-overview/
MariaDB [test]> SELECT * FROM oq_graph; Killed
It takes over a minute for it to return "Killed", all the while mysqld uses as much CPU as possible. But then, if I try to access it again:
MariaDB [test]> SELECT * FROM oq_graph; ERROR 2013 (HY000): Lost connection to MySQL server during query MariaDB [test]> SELECT * FROM oq_graph; ERROR 2006 (HY000): MySQL server has gone away No connection. Trying to reconnect... Connection id: 3 Current database: test +-------+--------+--------+--------+------+--------+ | latch | origid | destid | weight | seq | linkid | +-------+--------+--------+--------+------+--------+ | NULL | 1 | 2 | 1 | NULL | NULL | | NULL | 2 | 3 | 1 | NULL | NULL | | NULL | 2 | 6 | 1 | NULL | NULL | | NULL | 3 | 4 | 1 | NULL | NULL | | NULL | 4 | 5 | 1 | NULL | NULL | | NULL | 5 | 6 | 1 | NULL | NULL | +-------+--------+--------+--------+------+--------+ 6 rows in set (0.02 sec)
And then sometimes, it works as expected.
Accessing from PHP or Python has the same effect: 100% CPU load. I've yet to get a proper result returned from these environments.
Selecting from oq_backing works fine.
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Ryan, which storage engine is the backing table?
If you are able to run a debug version of mysqld, that'd be really helpful - upload the trace file in this issue so that we can see the flow of the system before it crashes.
For the crash, just checking your errorlog will already help - the backtrace provides good information for us. You may need to resolve the stacktrace (see manual) before submitting it here.
Basically the more detail you are able to provide us with regarding what steps cause the issue and then what happens exactly behind the scenes on your system, the faster we might be able to track down the issue and fix it!
Thanks
I believe it's InnoDB. I'll look into running debug.
I suspect this is the same bug as (patch proposed) MDEV-5891, especially if you tried to select on an empty table...
In the absence of further information, I think this is a duplicate of MDEV-5891. Please open a new issue if new information is available.
Upgraded to the recent 10.0.9, and for the most part is seems to be working at the cli level. However, I occasionally get a "Lost connection to server while processing query" (or something to that effect). I also still cannot access the data via python or php (mariadb shoots to 100% CPU still)