Re: Row locking and serializability

Hi Ruud,

Original posting compared traditional locking implementation to Oracle. Lets look into locking implementation first. In the passenger example the statement

select count(*) from passengers;

puts a read lock on the whole table, right? Oracle implementation would not, but 'select for update' will put the write lock. Putting write lock seems to be more restrictive at first, but again, writers do not block readers in Oracle, therefore, these two cases seems to be equivalent from throughput perspective.

Ruud de Koter wrote:

> Hi Vadim,
>
> You must be joking. This kills both performance and scalability
> with a single action. Please insert some indication of sarcasm
> or irony when you write something like this....
>
> Regards,
>
> Ruud de Koter
>
> Vadim Tropashko wrote:
> >
> > iggy_fernandez_at_my-deja.com wrote:
> >
> > > The question that remains unanswered is how
> > > serializability may be manually achieved when
> > > using Oracle.
> >
> > This one seems easy -- just lock "the whole" table:
> >
> > alter session set isolation_level=serializable;
> > select * from passengers for update;
> > insert into passengers values 'Z';
> > commit;
> >
> > Thransaction above is serializable indeed.
>
> --
> --------------------------------------------------------------------------------------
> Ruud de Koter HP OpenView Software Business Unit
> Senior Software Engineer IT Service Management Operation
> Telephone: +31 (20) 514 15 89 Van Diemenstraat 200
> Telefax : +31 (2) 514 15 90 PO Box 831
> Telnet : 547 - 1589 1000 AV Amsterdam, the Netherlands
> Email : ruud_dekoter_at_hp.com
>
> internet: http://www.openview.hp.com/itsm
> http://www.openview.hp.com/assetview
> intranet: http://ovweb.bbn.hp.com/itservicemanager
> --------------------------------------------------------------------------------------
Received on Mon Jul 19 1999 - 13:30:29 CDT