Oracle Logbook

February 25, 2013

The best advance in Oracle database 12c

Filed under: Uncategorized — heliodias @ 8:11 pm

Adaptive execution plans.

This new feature, by itself will justify many upgrade around the globe.

Most of database operation are repetitions, and as everywhere always have a “bad execution plan” due to lack of precise statistics. And this used to go over and over.

But now the database will gonna behaviour better and better.

I can imagine improvements in more 90% on hardest operation.

Decreasing in CPU demands and memory.






February 14, 2013

How to measure IO performance inside Oracle Database

Filed under: Uncategorized — heliodias @ 8:36 pm

The challenge was to create a baseline from Oracle database viewpoint which allow us to spot after a storage migration if the performance changed.

I created a “magical number” called Whole Mbytes per seconds. Which is the total write and read of the whole database operations, including background processes, redos write and of course the foreground processes divided by the IO wait per second.

select total_mb/trunc(value/100) from v$sysstat,
(select trunc(sum(value)/1024/1024) total_mb from v$sysstat where name in
(‘physical read total bytes’,’physical write total bytes’))
where name=’user I/O wait time’;

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