Обсуждение: BUG #4758: deadlock.c:944

The following bug has been logged online:

Bug reference:      4758
Logged by:          sergey
Email address:      opium@ydk.com.ua
PostgreSQL version: 8.4beta1
Operating system:   Linux 2.6.25-gentoo-r8
Description:        deadlock.c:944
Details:

i have table with 15 records

     Table "public.test"
 Column |  Type   | Modifiers
--------+---------+-----------
 y      | integer |


then i run 3 followng commands in parralel:

./bin/psql billy < sql.sql

in file sql.sql only 10000 statements "UPDATE test SET y=1;"

and what i see in log:

ERROR:  40P01: deadlock detected
DETAIL:  Process 10237 waits for ShareLock on transaction 165664; blocked by
process 10242.
        Process 10242 waits for ShareLock on transaction 165691; blocked by
process 10237.
        Process 10237: UPDATE test SET y=1;
        Process 10242: UPDATE test SET y=1;
HINT:  See server log for query details.
LOCATION:  DeadLockReport, deadlock.c:944

approximately one message per second

"sergey" <opium@ydk.com.ua> writes:
> ERROR:  40P01: deadlock detected
> DETAIL:  Process 10237 waits for ShareLock on transaction 165664; blocked by
> process 10242.
>         Process 10242 waits for ShareLock on transaction 165691; blocked by
> process 10237.
>         Process 10237: UPDATE test SET y=1;
>         Process 10242: UPDATE test SET y=1;
> HINT:  See server log for query details.
> LOCATION:  DeadLockReport, deadlock.c:944

This is not a bug.  Your code is trying to update the same rows in
conflicting orders.

            regards, tom lane