Oracle-L: Re: Oracle From a Sybase DBA perspective| What is a Database to S

From: Denny Koovakattu <denny_vk_at_yahoo.com>
Date: Sun, 31 Mar 2002 15:28:19 -0800
Message-ID: <F001.004376B6.20020331152819@fatcity.com>

Having worked with a lot of Sybase DBAs and having discussed why "Sybase Architecture is Inferior to Oracle's" and having helped them understand/learn Oracle, I know why Sybase DBAs find it difficult to understand Oracle. But there are a few things Sybase is better at.

Ablility to return result sets from procedures - Ref cursors or dbms_output donot match up to what Sybase offers
bcp out - It's time Oracle came up with some utility to extract the data in ascii format other than recommending "sqlplus and spool"
Replication - I like the Sybase replication architecture. This is a lot closer to what Quest offers (Shareplex).
Seperation of Schema and normal users. - The closest you could get to this is by using "alter session set current_schema". I am not familiar with LDAP. I believe we could be having something similar soon.

If you compare the architecture of both the products, Sybase architecture is inferior to Oracle. My favorite is the way the transaction logs are managed in Sybase. Its both the rollback segments and redo logs (but only one log) rolled into one. Simple explanation (Unless something changed in one of the newer versions) - The log gets reused only after checkpointed transactions are cleared. Open transactions will NOT be checkpointed. But open transactions will not be skipped to checkpoint commited transactions. All it takes is one small open transaction to fill up the log. And if the Sybase Server goes down at this point, recovery has to start at this point, replaying all the transactions including commited ones. I know of cases where recovery took hours because of this. And the lack of rollback segments mean Sybase has to put a shared lock on tables during SELECTs to get a read consistent view of the data. But then Sybase replication may not work without this "architecture".

I remember reading "The good thing about Oracle is it's so tunable and the bad thing about Oracle is it's so tunable". Change "tunable" to "features/options" and I guess that will explain why anybody who doesn't really understand the architecture find it so overwhelming. Try comparing Oracle Backup and Recovery options to Sybase's. Oracle has a lot of features/options than Sybase. Lack of understanding of the product make them not like the product. But I don't understand somebody not understanding the product after working on it for 3 years. My imagination's not up to the task ;)

Translating Sybase lingo to Oracle is not easy. In most cases there is no direct match.

Oracle Instance                - Sybase doesn't have one
Oracle Database                - Sybase Server
Oracle Schema                  - Sybase Database (Not completely true. The

Sybase Database also has storage allocated to it. More like a minature database within a database. For practical purposes schema makes sense.)

SYS User                       - sa User
SYS Schema & SYSTEM tablespace - master Database
Schema Owner                   - dbo User (Database Owner)
Users (Non-Schema Owners)      - Sybase Login/Users

alter session

  set current_schema=SCHEMA    - use DATABASE
Tablespace                     - Segment
Datafile                       - Device (There can be multiple segments on a

singe device.)

Regards,
Denny

Rachel Carmichael wrote:
>
> Ian,
>
> Having worked with Sybase years ago, I developed this "translation"
>
> Sybase instance = Oracle database
> Sybase database = Oracle tablespace
> Sybase dbo user = Oracle sys user
> Sybase master database = Oracle SYSTEM tablespace
>
> anyone have a better explanation?
>
> Rachel
>
> --- "MacGregor, Ian A." <ian_at_SLAC.Stanford.EDU> wrote:
> > Well, that certainly was interesting!! No database will always
> > compare favorably to others for every feature. There are some tings
> > SYBASE does better than Oracle. However, he is either ignorant of
> > such things as the "no logging" directive, or refuses to consider
> > them because they are not part of SYBASE. I believe that is his real
> > point, Oracle ain't Sybase. If methods to accomplish a task differ
> > Oracle's way is wrong. Oracle has lagged other database vendors in
> > facilitating getting the data out of the database, while doing a
> > superior job of lessening the chances of losing data.
> >
> > Perhaps someone with SYBASE experience can explain exactly what a
> > database is to Sybase. I infer from the posting that having
> > thousands of them on a single server is common place. I imagine it's
> > the opposite of parallel server: instead of multiple instances
> > associated with a single set of database files, a single instance is
> > associated with multiple sets of database files. Each set of files
> > being a database.
> >
> > Ian MacGregor
> > Stanford Linear Accelerator Center
> > ian_at_slac.stanford.edu
> >
> > -----Original Message-----
> > Sent: Friday, March 29, 2002 10:43 AM
> > To: Multiple recipients of list ORACLE-L
> >
> >
> > Dear list,
> >
> > Feel like having a good rant? Need to take some frustrations
> > out on lies, ignorance and misinformation?
> >
> > I received a document from a friend that live in both the Sybase
> > and Oracle worlds. He was interested in my comments on it
> > as he recognized it as a rant against Oracle that was full of
> > misinformation.
> >
> > Oracle has it's problems, but if you want to rant about it's
> > inadequacies, you should at least be accurate.
> >
> > Some of the things in here I can't address, such as the
> > IEEE number formats.
> >
> > Others are just plain stupid.
> >
> > The writer claims to have spent 3 years with Oracle, but he's
> > either lying or extraordinarily incompetent, I dunno which.
> >
> > Here's my proposal: I'm turning this document loose to the list.
> > I was going to comment on it myself, but it's fairly lengthy, and I
> > just don't have time to do it myself.
> >
> > Besides, I know that some of you relish such opportunities. :)
> >
> > It's in MS Word format. If you want to make comments about
> > any section of the document, include your comments in blue
> > font below that section.
> >
> > I will compile the comments, and send the annotated document
> > back to my friend. He can distribute it to his Sybase DBA friends
> > if he likes.
> >
> > I was kidding about the ranting. Please keep it objective and
> > professional.
> >
> > Please include your name at the top of the document. Tell me if
> > you want your name and email address included in the finished
> > document.
> >
> > The document can be found at:
> >
> > http://www.cybcon.com/~jkstill/Oracle_from_a_Sybase_DBA.doc
> >
> > Thanks,
> >
> > Jared

-- 
Denny Koovakattu
http://www.vivare.com/
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Denny Koovakattu
  INET: denny_vk_at_yahoo.com

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Received on Sun Mar 31 2002 - 17:28:19 CST