Re: algo for canceling a deadlocked transaction - Mailing list pgsql-general

From Thomas Poty
Subject Re: algo for canceling a deadlocked transaction
Date
Msg-id CAN_ctniAhCaDdTdmtvr9u37dsp7W9nt49bOS6uGoMV7Z4g9tJg@mail.gmail.com
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In response to Re: algo for canceling a deadlocked transaction  (Stephen Frost <sfrost@snowman.net>)
Responses Re: algo for canceling a deadlocked transaction
List pgsql-general
Hello Stephen,

> The short answer is "it's whichever one detected the deadlock."  The
> deadlock timeout fires after a lock has been held that long and if a
> deadlock is detected then the process detecting it will be canceled.

ok, and long  answer ? is it random?


> I'd strongly recommend reviewing your application and addressing
> deadlocks by changing how the application acquires locks to be
> consistent and to avoid lock escalation instead of worrying about how to
> predict a deadlock- a properly designed and written application
> shouldn't be causing deadlocks to happen in the first place.

I didn't want to predict the deadlock happening. I only want to know if it is predictable to know which transaction will be canceled.

Thank you

2018-04-09 15:51 GMT+02:00 Stephen Frost <sfrost@snowman.net>:
Greetings,

* Thomas Poty (thomas.poty@gmail.com) wrote:
> My question is : In case of a deadlock between 2 transaction,  how to know
> which transaction will be canceled? Is it predictable?

The short answer is "it's whichever one detected the deadlock."  The
deadlock timeout fires after a lock has been held that long and if a
deadlock is detected then the process detecting it will be canceled.

I'd strongly recommend reviewing your application and addressing
deadlocks by changing how the application acquires locks to be
consistent and to avoid lock escalation instead of worrying about how to
predict a deadlock- a properly designed and written application
shouldn't be causing deadlocks to happen in the first place.

Thanks!

Stephen

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