Referencing dba_extent pulls in the segment headers of all segments owned by 'BCA'. When you interrogate x$bh have nothing else in your sql. Dump the result set somewhere and then get the information from dba_extents so that you can match dbarfil and dbablk to a segment. I usually use excel and its vlookup function to do that.
At 09:19 AM 5/29/2003 -0800, you wrote:
I am reposting this in the hopes that someone can help me with this puzzler.
I am working on determining which objects have 'hot blocks'.
In two different sessions, I issue "select count(*) from random_data where rowid_rownum in (1,2,3);" repeatedly to see what happens with the touch count (x$bh.tch).
In another session, I look for the blocks related to this object by issuing the statement:
select x.owner, x.segment_name, x.segment_type, b.dbarfil, b.dbablk, b.class, b.state, sum(b.tc
from dba_extents x, x$bh b
where b.dbarfil = x.file_id
and b.dbablk between x.block_id and (x.block_id + blocks - 1)
and x.owner = 'BCA'
group by x.owner, x.segment_name, x.segment_type, b.dbarfil, b.dbablk, b.class, b.state;
[snip]
The oddity is that I have restarted the instance and have only issued queries against the random_data table. Since I am the only user on the system, I know that no other sessions are accessing the objects.
The interesting bit in all this is that the blocks other than random_data listed in x$bh are the segment headers.
select segment_name, file_id, block_id, blocks, block_id+blocks-1 from dba_extents where owner = 'BCA' and extent_id = 0 order by file_id, block_id;
Wolfgang Breitling Oracle7, 8, 8i, 9i OCP DBA Centrex Consulting Corporation http://www.centrexcc.com
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