Re: index rebuilding...

Not entirely weird.

It sounds like you have gone in with the semi-default 'ASS management' feature,
which is not a feature of the LMT as such, but a feature to replace freelist management.

Each segment has blocks reserved to hold maps of used blocks, with an indication of space available per block. Oracle then uses the process ID to decide which space-management block you should use to find some space, and which block referenced in the space management block you should first try. Consequently, a single row in a newly created 16block table COULD end up in the last block of the table.

Try the experiment again, but run up several sessions, keep them open, and repeat the experiment in each session in turn. I think in your case you will see either the first 8 or second 8 blocks formatted (if you don't get something so weird as an unformatted gap, go for a 32 block table), and the block used then varying from session to session.

In the case of the index - the root block is traditionally the block after the segment header block - so I think a special case is followed to format that block when the index is created, whatever the process id of the session that creates the index.

--
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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Noons wrote in message ...


>

>Has anyone here tried to dump the first extent off a LMT,

>table with just one block of data, 64K uniform alloc, 4096

>block size?  Ie, 16 blocks/extent?  Now, that was a surprise

>for me: Oracle takes an apparently weird choice as to which

>block gets data first!  Weird, I tell you.  :)

>

>Now do the same for an index on that same table, same tablespace.

>One block of index only, before it splits.  Weirder.

>

>9r2, of course.

>