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Oracle CPU Time

There are 3 kinds of CPU in the Oracle stats.

  1. Oracle CPU used
  2. System CPU used
  3. Oracle demand for CPU

Starting in 10g Oracle records both the CPU used by the instance as well as the load on the system in v$sysmetric. This is awesome as we can see how busy the system is and how much of the CPU Oracle is responsible for:

Where to begin with Oracle and SQL

Seeing more and more questions on “where do I start with Oracle if I want to be a DBA?”  My perspective is a bit off since I’ve been surrounded by Oracle for over 20 years.  I hardly remember what it was like to start with Oracle and starting with Oracle now in 2013 is quite different than starting with Oracle in 1990.

Here is my list and everything on this list is excellent. I’m sure I missed a few good ones, but maybe people can add them in the comments.

Start with Oracle Docs, they are free and good!

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Death of the Storage Array

When I wrote this article for The Register in October 2010, there was a torrent of naysayers and witch hunters spewing their opinions in the comments section. I don't have a problem with that, I was only expressing an opinion myself, after all. I don't actually own a time machine and so any of my […]

Death of the Storage Array

When I wrote this article for The Register in October 2010, there was a torrent of naysayers and witch hunters spewing their opinions in the comments section. I don't have a problem with that, I was only expressing an opinion myself, after all. I don't actually own a time machine and so any of my […]

12c Join Views

There are a couple of posts on the blog describing problems with updateable join views or, to be more precise, join views which were key-preserved but which the optimizer did not recognize as key-preserved. Both scenarios are addressed in 12c:

Oracle 12c: XMLIndex Support for Hash Partitioning

XMLIndex support for Hash Partitioning is now also supported in Oracle 12c. In Oracle 11 there was already support for RANGE and LIST partitioning, but not yet for HASH partitioning. Some examples for the later two: LIST Partitioning on XMLType -- -- Create partitioned LIST partitioned XMLType table --   DROP TABLE list_part_xml PURGE;  

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Oracle 12c: PGA_AGGREGATE_LIMIT

There is a new default in town. Mark my words, you will encounter the following during your 12c life-cycle… From the Oracle 12c Reference manual PGA_AGGREGATE_LIMIT: PGA_AGGREGATE_LIMIT PGA_AGGREGATE_LIMIT specifies a limit on the aggregate PGA memory consumed by the instance. There is no difference in behavior between PGA_AGGREGATE_LIMIT being explicitly set or being set to

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TIMESTAMP WITH TIME ZONE Aggregation

The TIMESTAMP WITH TIME ZONE data type that got introduced a long time ago is known for some oddities, for example Tony Hasler has a nice summary of some of them here.Here is another oddity that shows up when trying to aggregate on such a data type. Have a look at the following simple example:


create table t
as
select
rownum as id
, date '2000-01-01' + rownum - 1 as some_date
, cast(date '2000-01-01' + rownum - 1 as timestamp) as some_timestamp
, cast(date '2000-01-01' + rownum - 1 as timestamp with local time zone) as some_timestamp_with_local_tz
, cast(date '2000-01-01' + rownum - 1 as timestamp with time zone) as some_timestamp_with_timezone
from
dual
connect by