Re: Difference between NUM_ROWS and COUNT(*)

Thomas Klinger schrieb:

> Hi there!
>
> A small question:
> what's the difference between NUM_ROWS ind USER_TABLES and COUNT(*) from the
> same table?
> i.e. in USER_TABLES I have for the table X the value 32410 in NUM_ROWS. With
> a select count(*) from X; I get the value 38986.
> Does the second value depends on the High-Watermark? Or is there some other
> reason?
>
> Thanks for the answer.
>

The value NUM_ROWS in USER_TABLES is the amount of rows for the table X at the moment
when this table was analyzed with the ANALYZE-command. It will be out of date the very next moment
when some rows inserted in or deleted from that table. COUNT(*) always returns the current amount
of rows.

Regards, Stephan

--

Dipl.-Inf. (FH) Stephan Born   | beusen Consulting GmbH
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