Re: ISOLATION LEVEL
- From: "Niall Litchfield" <niall.litchfield@xxxxxxxxx>
- To: jkstill@xxxxxxxxx
- Date: Thu, 26 Jul 2007 19:05:58 +0100
This advantage of Oracle can be overstated.
See my, er, embarassed reply of July 10th. Oracle's results are only
ever consistent - an advantage certainly - but even then require
serializable transactions for reports more than a single select. So if
the some runtime is, say 16 hours, and the report is for what is the
current stock level of our warehouse, and the person querying is the
store manager an hour after the 'all stock must go' sale starts, when
he has a sneaking suspicion that all stock has in fact gone. Sometimes
waiting a protracted period for a result that is out of date, but
consistent is at least as unacceptable as not waiting for an
inconsistent result.
Then of course there is the assumption that the data being queried is,
well, accurate in the first place.
Niall
On 7/26/07, Jared Still <jkstill@xxxxxxxxx> wrote:
> On 7/13/07, Buchanan, Jason <oracle@xxxxxxxxxxxx> wrote:
> >
> > Depends on the report, depends on the company, etc. I've worked in
> > shops where the requirements of some reports didn't need
> > transactionally-consistent data and "WITH UR" was perfectly
> > satisfactory (DM/DW/VLDB). Doing the same type of report in Oracle
> > certainly would have required many gigabytes of undo.
> >
> >
>
> Inaccurate results are acceptable to avoid sacrificing some runtime and
> undo?
>
> --
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist
>
--
Niall Litchfield
Oracle DBA
http://www.orawin.info
--
//www.freelists.org/webpage/oracle-l
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