Error Deadlock Detected Detail
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Global Enqueue Services Deadlock Detected
from PL/SQL function. Please find the SQL statement in the code block. (Just example) BEGIN UPDATE accounts SET balance = 0 WHERE acct_name like 'A%'; UPDATE accounts SET balance = balance + 100 WHERE acct_name like '%A'; EXCEPTION WHEN OTHERS THEN RAISE NOTICE SQLERRM; END; I've found that the deadlock occurred during this statement was running. But i'm not sure that there were other statements trying to update this table in the same time (Rather deadlock detected while waiting for resource not cause I didn't found any statement which trying to update this table in my logging system). So, is it possible that the deadlock was occurred within this statement ? As i know, if we blocked whole statement with BEGIN/END. There will be the same transaction and should not be locked by itself. Thanks in advance, Stoper postgresql deadlock share|improve this question edited Apr 9 '12 at 18:02 Mosty Mostacho 28.5k85689 asked Apr 9 '12 at 17:55 Sathapanic Sriprom 751414 Do you have any triggers on accounts? Also do you use explicit locking? –strkol Apr 9 '12 at 18:08 By default, a transaction can observe changes committed by other transactions. For more information, see Transaction Isolation from the PostgreSQL documentation. –Joey Adams Apr 9 '12 at 18:13 @strkol Yes I have, but statement in that trigger is not related to this table. For the explicit locking is also yes. –Sathapanic Sriprom Apr 9 '12 at 18:35 add a comment| 3 Answers 3 active oldest votes up vote 7 down vote accepted This is not a PL/SQL function. Looks like PL/pgSQL. There is definitely some other process competing for the same resource. That is the nature of a deadlock. A function like you display can never deadlock itself. See comment by @kgrittn below, who is an expert on
with deadlocks in PostgreSQL, and provides a general workflow to handle deadlock bugs and details on how to get information from PostgresSQL. If you need a gentler introduction, take a look at the first article in this series. deadlock detected while waiting for resource oracle Debugging a deadlock - a workflow If you have to deal with a deadlock
Deadlock Detected Postgres
in a complex application, usually you'll have a defect that appears in time-dependent, load-dependent and user-dependent way. It's all too easy
Deadlock Detected Try To Fix It
to get lost in hypotheses! To avoid that try to work in a scientific way and follow a strategy. One such strategy is described below: look at Postgres logs first and try to get http://stackoverflow.com/questions/10077441/postgresql-deadlock-detected a rough idea of what is going on; determine what was going on at the exact time the deadlock happened. If you have a Web application, which page(s) were being loaded or submitted? If there are background jobs, were they running? If you have an API, were there clients using it? etc. Check all available logs as thoroughly as possible around the time the deadlock happened; if at http://www.moioli.net/progetti/postgres-deadlocks-debugging-guidelines/ all possible, try to trigger the problem in a reproducible way using information collected above. This might even be impossible in some cases, yet every effort should be taken to have the problem happening again predictably or you will not be able to validate any solution! based on information collected above, determine what transactions were in progress, what queries were completed before the deadlock and what queries were running at the time of the deadlock. In a big codebase this can be daunting, and ORMs such as Hibernate complicate things a lot by issuing automatically generated queries behind the scenes, yet you must, at some point, determine the active set of queries to have any chance; prototyping might help. You can, for example, attempt to write one or more test cases that exercise relevant code paths in your application and run them concurrently in order to better isolate affected components - see if you can get them deadlocking and check that the stack trace corresponds to the original. This has the advantage of automatically issue relevant queries to the RDBMS, which you can then figure out from logs (more on that in the next article); at this point, you should now ideally be able
Sign in Pricing Blog Support Search GitHub This repository Watch 119 Star 2,338 Fork 349 lib/pq Code Issues 39 Pull requests 27 Projects 0 Pulse Graphs New issue Weird "pq: deadlock detected" error #486 Closed azr opened https://github.com/lib/pq/issues/486 this Issue Aug 12, 2016 · 11 comments Projects None yet Labels None yet Milestone No milestone Assignees No one assigned 3 participants azr commented Aug 12, 2016 • edited Hello there, I have a view count that is backed by psql; now I probably should do it another way but; when I stress test it, from time to time I get thispq: deadlock detected error. Call is a DB.Exec() deadlock detected When this happened I had 7 goroutines panicking at the same line DB.Exec(). Is there a way to have more output/debug on this ? I'd be glad to help :) The psql db is a heroku hobby-dev with a limit of 20 simultaneous connections. johto commented Aug 12, 2016 I have a view count that is backed by psql I don't know what that means. Is there a way to have more output/debug error deadlock detected on this ? The way to debug deadlock errors is to look at the error message in the server log (it'll show the last statements executed by each transaction involved) and then analyze everything done in those transactions carefully. azr commented Aug 12, 2016 • edited Hey johto, I have a view count that is backed by psql means every time a user views something, I increment a dumb counter in a psql row. There is no transaction, its a DB.Exec() Edit: do you mean psql server logs or mine ? johto commented Aug 12, 2016 • edited There is no transaction, its a DB.Exec() You can't execute SQL statements in postgres without being in a transaction. If you're not in an explicit transaction block, postgres will start a transaction, execute your SQL statement and then commit (or roll back) that transaction. Edit: do you mean psql server logs or mine ? When I said "server logs", I meant postgres server logs. azr commented Aug 12, 2016 Ah okay, thanks for the explanations johto, on heroku Logs are not available on hobby-tier databases. :'( which means I'll have to find this in production logs... But reading what you just said my guess is that because the increment is done on the same ROW (by id) , t