Need some help in postgres locking mechanism - Mailing list pgsql-general

From santhosh kumar
Subject Need some help in postgres locking mechanism
Date
Msg-id CAOE+M7GZSfp+5wtN-FPrh3aBNo=597+=DgRZPMN6m6T-awmZyQ@mail.gmail.com
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Responses Re: Need some help in postgres locking mechanism  (Vick Khera <vivek@khera.org>)
List pgsql-general
Hi
I have two problems to discuss.an you please guide me how to proceed on this.
problem 1:
I have table X('a' is prmiary key) and table Y('b' is primary key).
Table Y has ''a''(X primary key) as foreign key.I have one job which runs once in one hour.I want to lock the rows in table Y.but this will also lock table X rows to avoid concurrent actions.My table X is used by other jobs as well for updation.
The solution what I thought is implement  KEY SHARE on 'a' column in table Y.That will help others jobs to update the corresponding rows in table X without any issue.

My doubt is how to keep  key share lock on "a" column in table Y.by default lock is on column 'b' which is primary key of table Y. My table X is so huge.I dont want any other locks on it.
we are using postgres 9.2.

one more doubt:If I implement key share lock on 'a' column,will the default locks on table X and table Y removed or not?

PLEASE PROVIDE SYNTAX AS WELL

problem2:
This is a different issue.I have a table Q('w' is primary key).When a job runs ,i want to lock some rows so that the other parallel job wont be considering this row.

what is the simple and best lock I can implement on these rows?I want with NOWAIT option.

kindly give solutions to above issues.I would be greatful for that.



Thanks
K.Santhosh

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