Re: Oracle internals.

In article <3c13bffb$0$2579$afc38c87_at_news.optusnet.com.au>, "Howard says...
>
>Comments below.
>HJR
>--
>----------------------------------------------
>Resources for Oracle: http://www.hjrdba.com
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>
>"Andrej" <andrej611_at_wp.pl> wrote in message
>news:9v0dag$9a1$1_at_korweta.task.gda.pl...
>> Hello,
>>
>> I am looking for the following info concering Oracle internals:
>> - how does Oracle know what blocks are assigned to what tables ? does is
>> blindly scan throug all the blocks ?
>
>No, it holds that information in data dictionary tables. Specifically, UET$
>records what extents exist, and who owns them. Tables such as OBJ$ and TAB$
>also come into play. In locally managed tablespace, a bitmap at the header
>of the tablespace indicates whether a block is reserved for use or not.
>Data dictionary entries still say which object owns which block.
>
>> - I know a single block can hold data for different segments.
>
>No it can't.

sure it can. CLUSTERS do just this...

>
>>So where is a
>> glue that holds a blocks/extents of a segment toegether ?
>
>There is no such substance.

the data dictionary for dictionary managed tablespaces (uet/fet) and the bitmap header for LMTs does this.

>
>
>> - what is internal structure of a datafile ? I am not asking to know the
>(c)
>> details but just a big picture. Once I did an append to one of a datafiles
>> with tar ...
>>
>> Please, point me to some reference on Oracle internals.
>
>Steve Adams has a book. O'Reilly, something like 'internal services for
>Oracle'. Go to his web site (www.ixora.com.au) and you'll be able to see it
>(and its accurate title, which I've forgotten) under the 'Resources' link).
>

I would say actually the Oracle concepts guide answers all of these questions very elegantly.

http://technet.oracle.com/doc/oracle8i_816/server.816/a76965/toc.htm

these "internals" aren't really that internal.....

>Regards
>HJR
>
>
>
>>
>> Just beeing courious,
>> Andrej
>>
>>
>
>

--
Thomas Kyte (tkyte@us.oracle.com)             http://asktom.oracle.com/ 
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