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Home -> Community -> Usenet -> c.d.o.server -> Re: Are these too harsh ?
I have no experience of standby databases (I know where too look when I need to however).
But I'd suggest a count(*) on an empty table taking so long is because oracle has to scan all the way up to the high watermark. A truncate would reset that. Delete doesn't.
"Norman Dunbar" <ndunbar_at_lynxfinancialsystems.co.uk> wrote in message
news:F43E6BAE5BB5D411A44C00805FBE740DAEED0D_at_apps.leeds.lfs.co.uk...
> Connor,
>
> I'm certain I know the answers to most of your questions, and for the
> rest I could find out pretty quickly. :o)
> But, I wouldn't class myself as a DBA (yet) - on the grounds of my lack
> of experience in many areas of DBAing. (Don't let the email sig fool you
> !)
> I might be too hard on myself, but I feel that in order to do a good job
> and have the title DBA, you have to know a whole load more that I
> currently do - and have experience of it as well. I'm getting there -
> even though what I do daily doesn't tax me much. (Anybody want a 'DBA'
> in Australia - please please !)
>
> Good luck in the hunt though !
>
> Norman.
>
> PS. Am I right in the following :
>
> Q. How do I allow end-user queries against a standby database without
> damaging its ability to act as a standby?
> A. I don't think you do. Once the standby database is opened, it is no
> longer a standby. So as for reading only from one ...
> Of course, if you mean a read only database (all tablespace in read only
> mode) then that's a different matter. Or have I missed something between
> O7/O8 and the present day as far as stand by databases go ?
>
> Q. You issue 'select count(*) from my_table;' and it takes a
> tremendously long time, but then return no rows. What could be causing
> this ?
> A. A shed load of blocks being put back onto the freelists after a
> recent and very large DELETE statement perhaps ?
>
> ------------------------------------------------------------------------
> --------
> Norman Dunbar EMail: NDunbar_at_LynxFinancialSystems.co.uk
> Database/Unix administrator Phone: 0113 289 6265
> Lynx Financial Systems Ltd. Fax: 0113 201 7265
> URL: http://www.LynxFinancialSystems.com
> ------------------------------------------------------------------------
> --------
>
Received on Tue Jun 26 2001 - 11:48:26 CDT