Re: Data Block Cleanup??

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.

cheers,

Magnus Lonnroth
Oracle Sweden
Mail: mloennro_at_oracle.com

[My opinions are not supported]
Received on Fri Oct 08 1993 - 03:30:58 CET