Re: dba_segments

Hi Joe,

dba_segments contains the characteristics of a segment, the physical mapping of a table, an index and so on. A segment can consist of multiple extents, just as a file can consist of multiple extents. dba_segments calculates the number of extents and the sum of all bytes in those extents. So the query below has an unnecessary sum, as dba_segments is already doing that calculation. What you get there, is the segments AAA, BBB,CCC and the total space allocated to them in Megabytes.

Hth,

Sybrand Bakker, Oracle DBA

Joe B wrote in message <37101ae5.48324131_at_news.ntplx.net>...
>Hello
>I am new to Oracle so please excuse me if this question is something I
should
>know...
>
>What does the dba_segments table contain and if someone gave me a query
like
>this ...
>
>select segment_name, sum(bytes)/1024/1024 from dba_segments
>where segmnet_name in ('AAA', 'BBB', 'CCC')
>group by segment_name;
>
>what bit of information were they trying to extract?
>
>
>TIA
>
>---------------------------------------------------------
>Reply to: joeba AT ntplx.net
Received on Sat Apr 10 1999 - 23:42:21 CDT