Re: want clarification from Oracle gurus regarding I/O

In article <8gh7go$o1m$1_at_nnrp1.deja.com>,   suresh_joshi_at_my-deja.com wrote:
> Hi, I want to know that how many i/o oracle will do to update 5 rows
 as
> result of the Update ... where ... ; statement.
> assume that the row has 10 column , the row being update is part of
> two indexes and oracle is using cost based optimzer and the blevel of
> the index is three and the db_block_size is 4k.
>

In Oracle Administrator's Guide (You can get docs on Oracle Technology Network) stated that:

1. Only 1 write operation is always done per transaction: redo record into redo log file during commit. Even this operation may be combined with other transactions if you have many transactions in the short period of time.
2. Oracle will update data in db block buffer cache for table, indexes and rollback segment blocks. But these blocks won't be written to disk until checkpoint or until server needs free buffers in cache.

That means that your question doesn't have practical sense. If you want to know average amount of db writes during many similar transactions, use V$SYSSTAT view and/or some monitor.

Alex Filonov.

> I appreciate if someone give me exactly what oracle do process the
> UPDATE request and how many i/o will happens because of that
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>

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Before you buy. Received on Fri May 26 2000 - 00:00:00 CDT