Re: Select are slow after delete command

Am I way off here or if you change your deletes to be followed up with a alter table XX deallocate unused - will that help?

• Dc

G R McHugh wrote:

> Deleting the rows in a table does not actually reset the high water mark. So
> when you are performing a full table scan, for example, the select statement
> still needs to look at all of the blocks allocated to the table. There are
> three ways to deal with this problem (I can think of):
>
> (1) truncate the table resets high water mark (and loses all records)
>
> (2) export the table with the deleted records
> drop the table
> import the previously exported table
>
> (3) create table temp
> as select * from xyz
> where <deletion_criteria>;
> drop table xyz;
> rename table temp to xyz;
>
> Hope that helps...
>
> Gabriel McHugh
> DBA Consultant
> gabe_riel_at_yahoo.com
>
> Břetislav Černík wrote in message <7ns7kt$ugi$1_at_ns.felk.cvut.cz>...
> >Hello
> >I found the folowing trouble.
> >When I delete many rows in table, the select works as slow as there are all
> >rows.
> >Are there any way, how can I clean table without drop table?
> >
> >Bretislav Cernik
> >xcernikb_at_hwlab.felk.cvut.cz
> >
> >
Received on Sat Aug 07 1999 - 16:13:22 CDT