Re: Data Block Cleanup??

In <MLOENNRO.93Oct8033058_at_wrpyr4.us.oracle.com> mloennro_at_us.oracle.com (Magnus Lonnroth) writes:

>In article <CEJ49B.8wA_at_world.std.com> edwards_at_world.std.com (Jonathan Edwards) writes:
 

>[stuff deleted]
 

> It may be the most simple, but also very inefficient. In many situations
> this would lead to extra, gratuitous disk writes. It should be easy to
> do this cleanup prior to purging a block from memory. I would be very
> surprised if this wasn't the case, but I will look into it anyway.
 

>1) Data-blocks may need to be flushed to disk before a transaction
> is completed. Do you want to read it back in for cleanup when the
> user issues a commit ?
 

>2) Server processes are happily unaware of when data-blocks are flushed.
 

>3) dbwr is happily unaware of any transactions.
 

>4) If multiple processes are updating the same data-block, who should
> clean it and when ?
 

>Your suggestions require a lot of overhead to several components,
>including dbwr and server-processes.
 

>The Oracle system architecture was very carefully designed for maximum
>throughput. It works very fine, and one of the few changes needed to
>improve the architecture, which was introduced in Oracle7, was shared
>SQL and multi-threaded servers. The rest, including block cleanup, is
>more or less the same as in Oracle v6.

I agree with your first five comments. The sixth, however, is something else!

[Flame On...]
The implication that because something survived from 6 to 7 it must be good, which together with "few changes needed" makes it seem that when you said "improve" you really wanted to say "perfect", is somewhat over the top.

The fact that the block is allowed to get into a state where it needs cleanup is the unforgivable design flaw! This wastes storage space in the block, and i/o and clock cycles in cleaning it up.

Don't get me wrong. I think that ORACLE7 is a pretty good RDBMS. But it sure ain't perfect! Not even as close as "very fine"! [Flame Off...]

>cheers,
 

>Magnus Lonnroth
>Oracle Sweden
>Mail: mloennro_at_oracle.com
 

>[My opinions are not supported]

Now, given that english is (presumably) not your native tongue, and that the implication may not come over so strongly in american anyway, and that your employment status entitles you to (some) bias, I realise that I myself have gone OTT (Over The Top).

Nevertheless, I'm in a bolshy mood and I shall let it stand!

graeme

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