Re: Why does a SELECT query needs REDO?

Jining Han wrote:
> In a 10.1.0.4 2-node RAC on HP-UX Itanuim, I have a database running
> which doesn't seem to have any DML activities. Now I run a long
> running SQL query (with SUM, GROUP BY), and the AUTOTRACE stats looks
> like this:
>
> Statistics
> ----------------------------------------------------------
> 482 recursive calls
> 3 db block gets
> 3932472 consistent gets
> 3831470 physical reads
> 7749080 redo size
> 2486 bytes sent via SQL*Net to client
> 686 bytes received via SQL*Net from client
> 1 SQL*Net roundtrips to/from client
> 9 sorts (memory)
> 0 sorts (disk)
> 0 rows processed
>
> I am wondering why there's 7749080 redo size (physical read, I assume)
> involved.

Google around on "delayed block cleanout" this question has been addressed all over the oracle universe Received on Thu Feb 09 2006 - 11:23:20 CST