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Re: Newbie's Oracle 9i impression: it sucks

From: SQLJoe <sqljoe_at_aol.com>
Date: 20 May 2002 21:19:40 GMT
Message-ID: <20020520171940.09238.00000763@mb-mq.aol.com>

>If I update the emp table, in Oracle, you can read the emp table, and you
>will see the data as it was before I started updating it. That's the
>rollback mechanism being used to generate read-consistent images of data.
>
>Try that in SQL Server (or Sybase etc etc), and you will discover that,
>unless you force the issue, your select is blocked by my update. Only when I
>commit can you read.

Actually, you are factually incorrect. MS SQL does provide INSERTED and DELETED tables which allow you to view either inserted or deleted data BEFORE it is comitted.

As far as rollback is concerned, MS SQL does allow partial rollbacks and have savepoints etc.

>That's an architectural issue of the rdbms itself, and no amount of O/S
>improvement or hardware will deal with it.
>
>Also architecturally-related is SQL Server 2000's insistence on 8Kb blocks
>("pages" if you prefer). That's performance limiting. Also it has a problem
>with long-running transactions (as does Informix amongst others) because the
>same mechanism is used for both transaction recovery and transaction
>rollback. If your transaction takes up more than half the log, it
>automatically fails, because it needs as much room to roll the transaction
>back as it took to generate it in the first place. Oracle's separation of
>redo from rollback means that this simply isn't an issue for it.

I bet this is one of the 20-30% of features in Oracle that most Oracle DBA and Developers never end up changing or using. Chaning the page (or block) size rarely makes much difference. But I will admit Oracle allows you to configure the page (or block) size while MS SQL does not (set at 8KB).

Jinsoo
MCDBA, MCSD, MCSE+I Received on Mon May 20 2002 - 16:19:40 CDT

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