[BUGS] BUG advisory_lock

[Eugen.Konkov]

DECLARE
  varUnlocked boolean;
BEGIN
varUnlocked:= pg_try_advisory_lock( 783264760123456 ); -- Try to lock function
IF not varUnlocked THEN return NULL; END IF; -- exit if locking is unsucessfull

WRONG QUERY HERE WHICH INTERRUPT EXECUTION

varUnlocked:= pg_advisory_unlock( 783264760123456 ); -- unlock function
END

NEXT time when I run this function I always get NULL until server reboot

EXPECTED: Pg must unlock if function execution failed

Re: [BUGS] BUG #4116: Cannot create tablespace: could not set permissions on directory

[Graham Leggett]

Tom Lane wrote:


This code makes the incorrect assumption that the platform will allow the
postgres user to set the permissions using chmod.



Is this something we should do anything about?


IMHO, no.  The reason for actually doing the chmod is to verify that we
own the directory.  If it fails, we don't own the directory in any
meaningful sense.  I think the complainant's real problem is that he's
misconfigured his SELinux permissions.


I'm afraid the machine came with SELinux permissions pre-misconfigured 
for me, and postgres didn't help the situation at all by sending me on a 
wild goose chase.


The correct way to check the permissions are correct is by testing the 
current permission values against what they should be, and then failing 
clearly and explicitly with a meaningful error message. Right now the 
code takes a short cut, which is easy for the coder, but very painful 
for the long suffering administrator.


Regards,
Graham
--


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Re: [BUGS] BUG advisory_lock

[Tom Lane]

<[EMAIL PROTECTED]> writes:
> EXPECTED: Pg must unlock if function execution failed

This is not a bug; it is the intended and documented behavior
of advisory locks.

regards, tom lane

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Re: [BUGS] BUG advisory_lock

[Alvaro Herrera]

[EMAIL PROTECTED] wrote:
> DECLARE
>   varUnlocked boolean;
> BEGIN
> varUnlocked:= pg_try_advisory_lock( 783264760123456 ); -- Try to lock function
> IF not varUnlocked THEN return NULL; END IF; -- exit if locking is 
> unsucessfull
> 
> WRONG QUERY HERE WHICH INTERRUPT EXECUTION
> 
> varUnlocked:= pg_advisory_unlock( 783264760123456 ); -- unlock function
> END
> 
> NEXT time when I run this function I always get NULL until server reboot
> 
> EXPECTED: Pg must unlock if function execution failed

You can unlock it in an EXCEPTION block to be safe.

-- 
Alvaro Herrerahttp://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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