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Re: Transactions and SavePoints

From: Marko Ristola <marko(dot)ristola(at)kolumbus(dot)fi>
To:
Cc: pgsql-odbc(at)postgresql(dot)org
Subject: Re: Transactions and SavePoints
Date: 2005-08-31 16:30:09
Message-ID: 4315DB11.8050300@kolumbus.fi (view raw or flat)
Thread:
Lists: pgsql-odbc
Hi

I tried to write SAVEPOINT SQL support into PsqlODBC in Summer.

I was able to implement some suport for savepoint creation, savepoint
rollback and savepoint RELEASE.

I didn't understand, how the query results should behave at savepoint
rollbacks.

You can find more information about my thoughts about savepoint
implementation on this list ealier this year, or with Google.

Main design issue was, that SAVEPOINT tracking must be implemented
into PSQLODBC.

That's what I implemented:
- Linked list of all defined savepoints.
- Maintain the list during SAVEPOINT maintenance functions.

Savepoint command parsing speed was 600000 commands per second,
that I wrote (UTF-8). With UCS-4 , without a state machine, it was
300000 commands per second. The subsystem's speed was okay.

I implemented a full PostgreSQL SQL SAVEPOINT support with
the Bison/Flex parser, because it is easy, but that part is
not at all easy to integrate into an existing PsqlODBC driver.

Are you interested in a patch for the mergeable part of the savepoint 
support?

Regards,
Marko Ristola

Carlos Henrique Reimer wrote:

> Is there a ODBC flavor than can implement ROLLBACK TO SAVEPOINT?
>  
> Marko Ristola wrote:
> > Unfortunately SAVEPOINTs are not implemented in PsqlODBC yet.
> >
> >
> >ROLLBACK TO SAVEPOINT -case is easy to fix, but the full
> >implementation is hard to make correctly for psqlodbc, at least for me.
> >
> >Marko Ristola
> >
> >>Cleber Nardelli wrote:
> >>
> >>
> >>Hello.
> >>I am using the Driver odbc for access to postgresql. I have a 
> referring problem to the cancellation of the transaction when
> >>some error
> >>is found at the moment of the execution of the same one. I try to 
> execute this sql command:
> >>
> >>
> >>BEGIN TRANSACTION;
> >> DELETE FROM TABL1 WHERE ID = 1;
> >> INSERT INTO TABL1 VALUES (1,1);
> >> SAVEPOINT SVPT;
> >> INSERT INTO TABL1 VALUES (1,1);
> >> ROLLBACK TO SAVEPOINT SPVT;
> >>COMMIT;
> >>
> >>When I try to insert as register it accuses to error with key 
> duplicate. Ok. But I do not want to cancel the transaction I I need to 
> only continue
> >>with the same one skirting this error. For this reason I am using
> >>SavePoints but it generates the error:
> >>"ERROR: ROLLBACK TO SAVEPOINT may only be used in transaction blocks"
> >>
> >>Necessary of the your help. I thank
> >>
> >>Yours truly
> >>
>
> ------------------------------------------------------------------------
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Subject: Re: Transactions and SavePoints
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