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From "Karl Wright (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-5073) Derby deadlocks without recourse on simultaneous correlated subqueries
Date Thu, 17 Mar 2011 07:52:29 GMT

    [ https://issues.apache.org/jira/browse/DERBY-5073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13007843#comment-13007843
] 

Karl Wright commented on DERBY-5073:
------------------------------------

Turning on query plan output had some interesting results.  The following queries are doing
full table scans.  In all cases, I cannot see why the planner does not use an existing index
that was created specifically to support the query.  The other interesting thing to note is
that NONE of these queries appeared in my list of "long running queries" above, so they were
not involved in the 30-minute stall recorded there.  But maybe the underlying cause is similar?

SELECT parentidhash FROM intrinsiclink WHERE (jobid=? AND linktype=? AND parentidhash=? AND
childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=?
AND linktype=? AND parentidhash=? AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=?
AND childidhash=?) OR(jobid=? AND linktype=? AND parentidhash=? AND childidhash=?)
(identical index exists: intrinsiclink: (jobid,linktype,parentidhash,childidhash) )

SELECT id,distance,linktype FROM hopcount WHERE (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?)
(identical index exists: hopcount: (jobid,linktype,parentidhash) )

SELECT id FROM jobqueue WHERE (jobid=? AND status=?) OR (jobid=? AND status=?) OR (jobid=?
AND status=?) OR (jobid=? AND status=?) OR (jobid=? AND status=?) OR (jobid=? AND status=?)
(identical index exists: jobqueue: (jobid,status) )

SELECT parentidhash,linktype,distance FROM hopcount WHERE  (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?) OR (jobid=? AND linktype=? AND parentidhash=?)
OR (jobid=? AND linktype=? AND parentidhash=?)
(identical index exists: hopcount: (jobid,linktype,parentidhash) )

FWIW, all of these queries use the corresponding index when run under PostgreSQL.
I'm happy to create a new ticket for this problem, if appropriate.  Comments?




> Derby deadlocks without recourse on simultaneous correlated subqueries
> ----------------------------------------------------------------------
>
>                 Key: DERBY-5073
>                 URL: https://issues.apache.org/jira/browse/DERBY-5073
>             Project: Derby
>          Issue Type: Bug
>          Components: Services
>    Affects Versions: 10.0.2.1, 10.1.2.1, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.3.0, 10.6.2.1,
10.7.1.1, 10.8.0.0
>            Reporter: Karl Wright
>         Attachments: Derby5073.java, derby-5073-1a.diff, derby-5073-1b.diff
>
>
> When the following two queries are run against tables that contain the necessary fields,
using multiple threads, Derby deadlocks and none of the queries ever returns.  Derby apparently
detects no deadlock condition, either.
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE t1.parentidhash
IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid) AND t0.jobid=?
> SELECT t0.* FROM jobqueue t0 WHERE EXISTS(SELECT 'x' FROM carrydown t1 WHERE t1.parentidhash
IN (?) AND t1.childidhash=t0.dochash AND t0.jobid=t1.jobid AND t1.newField=?) AND t0.jobid=?
> This code comes from Apache ManifoldCF, and has occurred when there are five or more
threads trying to execute these two queries at the same time.  Originally we found this on
10.5.3.0.  It was hoped that 10.7.1.1 would fix the problem, but it hasn't.

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