Re: Row Migration

Larry is the SQL guru. Every time he drops a pearl of wisdom like "we really want to make sure all the not-null columns are identified because it can affect the ability of the optimizer to transform a corelated IN subquery into an equi-join, and allow us to drop this index now that we won't need it for a correlated lookup, which will force all of our queries to rip through this table using hash joins" I wonder how the heck he KNOWS all that stuff.

I THINK it is just pure brains, although sometimes I suspect he has a deal with the devil ... or Larry Ellison.

:>)

Jack  

> don't feel too sheepish, I didn't know it either. Larry is the SQL
guru
> and I bow to his knowledge. and had already saved off this email as
> this sort of update is something we do often and I ALWAYS have
problems
> figuring out the correct SQL :)
>
> rachel
> --- Jared Still <jkstill_at_cybcon.com> wrote:
> >
> > Geez, I didn't know you could do that.
> >
> > Sheepishly,
> >
> > Jared
> >
> > On Friday 27 December 2002 03:38, Larry Elkins wrote:
> > > Someone asked in a back channel email if parallelism is used. The
> > select
> > > portion of the update statement uses parallelism (though the
> > updates
> > > themselves get serialized) through the use of an in-line join
> > update (to
> > > avoid the second sub-query commonly used to constrain the rows
> > being
> > > updated):
> > >
> > > Update (Select /*+ parallel hints */ ....
> > > From a,b
> > > Where a.key = b.key)
> > > Set a.col1 = b.col1,
> > > a.col2 = b.col2
> > > .....
> > >
> > > Regards,
> > >
> > > Larry G. Elkins
> > > elkinsl_at_flash.net
> > > 214.954.1781
> > >
> > > > -----Original Message-----
> > > > From: root_at_fatcity.com [mailto:root_at_fatcity.com]On Behalf Of
> > Larry
> > > > Elkins
> > > > Sent: Thursday, December 26, 2002 6:09 PM
> > > > To: Multiple recipients of list ORACLE-L
> > > > Subject: Row Migration
> > > >
> > > >
> > > > Listers,
> > > >
> > > > 8.1.7.4 64 Bit Solaris
> > > >
> > > > Does row migration utilize DB File Sequential Reads on the
table?
> > Off the
> > > > top of my head I would expect so, but I've never tested
something
> > > > like that
> > > > before.
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Jared Still
> > INET: jkstill_at_cybcon.com
> >
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services
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Thanks,

Jack Silvey

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Jack Silvey
  INET: oracle-l_at_warehousedba.com

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