Re: Parallel Insert and Delete operation

Thanks Albe Laurenz, Moshe Jacobson

@Albe - I got you first point. The second point is little skeptical because postgres could have been avoided this lock by using MVCC. Please correct me if I am wrong?
@ Jacobson - it could be possible that foreign key violation may arise but when it arise the procedure could have been stopped and it could be rollback the transaction. Please correct me if I am wrong?

Here, I want both operation should successfully run. So what I have to do. I would like to do some prototype test on this, hence please tell me is that possible to do it from pgadmin or I have write some example programming code on this.

Thanks & Regards,
Ramkumar

From: Moshe Jacobson [mailto:moshe(at)neadwerx(dot)com]
Sent: Wednesday, October 31, 2012 9:01 PM
To: Albe Laurenz
Cc: Yelai, Ramkumar IN BLR STS; pgsql-general(at)postgresql(dot)org
Subject: Re: [GENERAL] Parallel Insert and Delete operation

It is also possible that you will get a foreign key violation exception on the process inserting into table 2, but you will not get database inconsistency.
On Wed, Oct 31, 2012 at 9:33 AM, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at<mailto:laurenz(dot)albe(at)wien(dot)gv(dot)at>> wrote:
Yelai, Ramkumar IN BLR STS worte:
> Sent: Wednesday, October 31, 2012 12:40 PM
> To: pgsql-general(at)postgresql(dot)org<mailto:pgsql-general(at)postgresql(dot)org>
> Subject: [GENERAL] Parallel Insert and Delete operation
>
> Hi All,
>
> Please clarify me the following example.
>
> I have 2 tables
>
> Table1 - ( it has one primary key and few columns )
> Table2 - ( it has one primary key and few columns. It has one
foreign key, which refers table1
> primary key ).
>
> I have 2 operations, which are written in pl/pgsql procedure.
>
> Operation1() - Inserts the records to table2 at every hour basis.
> Operation2() - Delete the records from Table 1 and Table2 based on the
primary key.
>
> What if both operations are running at the time for the same primary
key.
>
> what I have to take care to run these two operations perfectly without
creating inconsistency in
> database.
With the foreign key in place there can be no entry in table2
that does not have a corresponding entry in table1.

Concurrency is solved with locks, so one of the concurrent
operations might have to wait until the other one is done.

That is handled by the database system automatically.

Yours,
Laurenz Albe

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