RE: HELP : doubts regarding --- Tablespace ,Roll Segment , diff between oracle 8i and 9i, and between oracle 8i and previous versions - urgent

From: Mark Leith <mark_at_cool-tools.co.uk>
Date: Tue, 27 Nov 2001 08:06:49 -0800
Message-ID: <F001.003CDB9D.20011127075025@fatcity.com>

sangeetha,

1. If a tablespace is deleted all of the tables, indexes or rollback segments that reside in that tablespace will also be deleted. Users are not stored in a tablespace, except in the SYSTEM tablespace - which you DON'T want to delete as it is the tablespace that runs the Oracle system.
2. Rollback segments are created to give users a "read consistent view". an example:

Scott wants to update the EMP table:

EMPID EMPNAME DEPT
----- ------- -----

9567 Jones SALES

and set Jones' department to Support as he's moved jobs. Scott issues:

update emp set dept = 'SUPPORT' where empname = 'JONES';

but he does not COMMIT the change, as he needs to move on and do some other things..

Frank comes along, and is trying to find out what Jones' department is, and issues:

select empid, empname, dept from scott.emp where empname = 'JONES';

but scott as still not commited the change that he issued earlier. Frank will still see:

EMPID EMPNAME DEPT
----- ------- -----

9567 Jones SALES

When you create your database, you should add at least one "non-system" rollback segment to be able to build tablespaces, and tables. When the database is created there is one rollback sgement created in the SYSTEM tablespace - but this is supposed to be used explicitly for system "transactions".

3) Exact differences are hard to explain without going in to a new paper or something.. The major enhancements are Automatic Undo Management or AUM (the above mentioned rollback segments are handled automagically for you), flashback query (another addition stemming from AUM), Oracle managed files, resumable transactions, online schema changes, new datatypes, and new SQL commands such as MERGE. There is a member of this list - Joes Testa - who is currently sending out (bi?)weekly emails to the list on the new features of 9i with examples and tests that he has performed. Very good reading!

8i also brought a wealth of new features from 7, such as locally managed tablespaces, java support, xml, partitioning, Index organised tables.. the list could go on for a while... The best bet is to get on to a web site like http://otn.oracle.com as they have a wealth of "New Features", FAQ type documents..

Welcome to the list!!

HTH Mark

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-----Original Message-----
Sent: 27 November 2001 14:30
To: Multiple recipients of list ORACLE-L between oracle 8i and 9i, and between oracle 8i and previous versions - urgent

hi list,

       i enrolled in this list jus today and it was really nice to see the questions and the responses that were posted.....here i've got few doubts.....if possible plz do clear them as soon as possible, as comming nov 30th is my project presentation.

1)If a tablespace is deleted will the users and tables created in that tablespace get deleted?,if not in which tablespace will the users and tables get stored.

2)what is the function of Roll Segment?...is it necessary to create it every time we create tablespace?

3)plz do give me the exact difference between oracle8i and oracle9i,ie., what are the advancements in Oracle9i not present in oracle 8i.

d) diff between oracle8i and its previous versions.

plz do clear all or any of the above doubts. awaiting for all u're replies eagerly.

regards
sangeetha

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Received on Tue Nov 27 2001 - 10:06:49 CST