Re: oracle - mysql comparison

Hello Daniel,

"Daniel Morgan" <damorgan_at_x.washington.edu> wrote in message news:1089945278.134355_at_yasure...
> VC wrote:
>
> > A correct concurrency control/model ensures that all the permitted
> > transactions are serializable. In this sense, databases like DB2 or
MSSQL
> > implement a correct concurrency model albeit at the expense of lower
> > concurrency in some circumstances. Funnily enough, none of the Oracle
> > isolation levels can make the same promise, i.e. ensure serializable
> > transaction histories, in any of its isolation levels. Usually, it's
quite
> > easy to obtain correct results by augmenting an isolation level with
> > something like 'select for update', though..
>
> And if this is true why, exactly, would anyone care at the expense of
> being able to extract an accurate answer from a database without
> performing table locks on all resources?
>

I am not sure what specific part of my message the word *this* ('if this is true') refers to, but assuming it's the last sentence then you surely know that 'select for update' takes write (TX) lock on all the rows involed A locking scheduler would take *read* row level locks in similar circumstances automatically. If my interpretaion is incorrect, please elaborate.

VC

> Daniel Morgan
>
Received on Fri Jul 16 2004 - 07:00:03 CDT