Re: SQL Diff ?

On Saturday 25 August 2007 23:49:39 Ron Johnson wrote:
> On 08/25/07 22:21, Kevin Kempter wrote:
> > On Saturday 25 August 2007 21:10:19 Ron Johnson wrote:
> >> On 08/25/07 21:51, Kevin Kempter wrote:
> >>> Hi List;
> >>>
> >>> I have a very large table (52million rows) - I'm creating a copy of it
> >>> to rid it of 35G worth of dead space, then I'll do a sync, drop the
> >>> original table and rename table2.
> >>
> >> What is your definition of "dead space"?
> >>
> >> Bad rows, duplicate rows, old rows?  Something else?
> >
> > deleted rows that should have been cleaned up with vacuum, problem is the
> > client let it go so long that now I cant get a vacuum to finish cause it
> > impacts the day2day operations too much.  Long story, see my recent
> > questions on the performance list for more info.
>
> OK.
>
> >>> Once I have the table2 as a copy of table1 what's the best way to
> >>> select all rows that have been changed, modified in table1  since the
> >>> initial laod from table1 into table2?
>
> Is this a 24x7 database?

Yes. with little room for extra overhead


>
> >>> Also I'll need to delete any rows in table2 that no longer remain in
> >>> table1.
> >>>
> >>> There is no change date column
> >>> I could do something like select * from table1 where col1 || col2 ||
> >>> col3 etc not in (select col1 || col2 || col3 etc from table2)
> >>>
> >>> but this would be ineffecient & slow.
> >>>
> >>> Anyone have a suggestion to do this in an efficient manner?
> >>>
> >>> Thanks in advance