Re: database table write on read

What I think is:
Every transaction which alter a database block make a transaction entry in the touched block. This entry will removed in future by another transaction, maybe a select. This will result in dirty blocks which will written by dbwr.

Best regards
Andreas Prusch

In article <6p5hn9$gh8$1_at_newssvr04-int.news.prodigy.com>,   "Duane Tiemann" <duanetiemann_at_prodigy.net> wrote:
> We have observed some file write activty by Oracle which we don't
> understand. We've replicated the situation on a test system as follows:
>
> We insert a few rows which have a long raw column with 64000 bytes in it.
> After waiting several minutes (in which the rows seem to be successfully
> logged and written to the database) we retrieve any value from one of the
> rows.
>
> The retrieval results in write activity to the table. This is documented by
> "select * from v$filestat" as well as AIX's iostat; The number of blocks
> written is the same as the number of database blocks included in all the
> rows inserted.
>
> Can anyone tell us why this write activity occurs?
>
> BTW, the 'extra' writing does not occur if we place 6K or less in the long
> raw column. It also does not occur on subsequent retievals -- only the
> first.
>
> More details:
>
> Oracle Version 7.3.3
> AIX Version 4.2.1
> Database block size 16384
>
> Thanks,
>
> Duane Tiemann
> Prodigy Services Co.
> duanetiemann_at_prodigy.net
>
>

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