Re: The disk space used by a certain table??!!

Thanks for your reply.
But for my No.3 question, I mistyped. Actually the question I want to ask is:
If the 'bytes' in 'dba_segments' is the allocated disk space by table 'tab', why is it much more than 'avg_row_len*num_rows'(even you can add more space for row header)? Since the pctfree is so small.

Thanks again!

In article <961622820.5673.0.pluto.d4ee154e_at_news.demon.nl>,   "Sybrand Bakker" <postbus_at_sybrandb.demon.nl> wrote:
> Answers embedded
> <ibm_97_at_yahoo.com> wrote in message news:8ir8c7
 $nsu$1_at_nnrp1.deja.com...
> > Hi, there:
> >
> > Oracle 8i for solaris 2.6
> > table 'tab': pctfree is 5, pctused is 75.
> > database block size is 8k.
> >
> > Analyae table 'tab':
> > analyze table tab estimate statistics sample 20 percent;
> >
> > From the 'user_tables':
> > blocks: 1754
> > num_rows:62424
> > avg_row_len: 210
> >
> > What does the 'blocks' mean in here?
>
> The number of used blocks (extrapolated, as you only sampled 20
 percent)
> >
> > From the 'dba_segments' get the corresponding info for this 'tab'
 table:
> > bytes: 20971520
> > blocks: 2560
> >
> > My questions:
> >
> > 1. what's the difference between the two 'blocks'?
> The former is in use the latter is allocated
>
> > 2. what does the 'avg_row_len*num_rows' mean? Does it mean the real
 used
> > disk space by the 'tab'?
> No, this formula will not return the used space as the row overhead
 is not
> included.
>
> > 3. If the 'bytes' in 'dba_segments' is the allocated disk space by
 table
> > 'tab', why is it much more than 'avg_row_len'? since the pctfree is
 so
> > small.
> >
> avg_row_len is the average length of an individual, single, row, not
 of all
> rows. Hence it is normal to be small
>
> > THanks a lot!!
> >
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
>
> Hth,
>
> Sybrand Bakker, Oracle DBA
>
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Thu Jun 22 2000 - 00:00:00 CDT