Re: WHATS WRONG WITH DBA_TABLES?

Mark Styles wrote:
>
> Charles Walker <cwalker_at_explorer.csc.com> wrote:
> >When I run the following I get no rows
> >
> >SQL> SELECT NUM_ROWS FROM SYS.DBA_TABLES WHERE TABLE_NAME ='NEW_MARINES';
> >
> > NUM_ROWS
> >----------
> >
> >But when I do a count I get rows...whats up?
> >
> >SQL> SELECT COUNT(*) FROM TFDSS.NEW_MARINES;
> >
> > COUNT(*)
> >----------
> > 569438
> >
>
> The statistical fields on tables such as dba_tables are not kept
> up to date automatically, you have to ANALYZE the table regularly.
> When you ANALYZE a table, you can either COMPUTE or ESTIMATE these
> statistics, as COMPUTE can take a long time on large tables.
>
> If you can, its nice to analyze all your tables every night, or
> maybe every weekend (the statistics generated get used by the cost
> based optimiser to work out the fastest query paths).
>
> How often you analyze depends on how often your table stats are
> likely to change, and how up to date you need to keep the data.
>
> --
> ** Mark Styles aka Small -- Opinions expressed here are my own -- **
> ** marks_at_teleord.co.uk -- unless otherwise specified -- **
> ** This whole world's wild at heart and weird on top **

But.... you may want to save/print the info then disable statistics for you're tables... sometimes things go slooooower with the current optimizer.

-Joel Received on Thu Apr 18 1996 - 00:00:00 CEST