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September 2015

Hyper-threading: measure its impact during SLOB runs thanks to numactl and turbostat

Introduction

As you probably know, a single physical CPU core with hyper-threading appears as two logical CPUs to an operating system. 

While the operating system sees two CPUs for each core, the actual CPU hardware only has a single set of execution resources for each core.

Hyper-threading can help speed your system up, but it’s nowhere near as good as having additional cores.

Out of curiosity, I checked the impact of hyper-threading on the number of logical IO per second (LIOPS) during SLOB runs. The main idea is to compare:

Index Advanced Compression: Multi-Column Index Part II (Blow Out)

I previously discussed how Index Advanced Compression can automatically determine not only the correct number of columns to compress, but also the correct number of columns to compress within specific leaf blocks of the index. However, this doesn’t mean we can just order the columns within the index without due consideration from a “compression” perspective. As […]

OOW2015 Middleware Management

This posting covers the Middleware Management sessions at OOW2015. Note that these are middleware management via Enterprise Manager, as opposed to sessions specifically covering middleware features and functions. Also, I have not duplicated here sessions I have already documented under Oracle Management Cloud or Private Cloud / DBLM, so please visit those posts for sessions that fall under both categories. The following sessions fall under this category:

Oracle 12c SQL – TRUNCATE TABLE … CASCADE

Oracle 12c updates the TRUNCATE TABLE statement allowing the use of CASCADE to eliminate values in tables that are referentially connected.

This option is something that some shops were looking for from Oracle; it is possible that your shop will not find the need for this option.

 

Here is the syntax:

#0000ff;"> TRUNCATE TABLE ID_TEST1 CASCADE;

(other TRUNCATE TABLE options such as those for MATERIALIZED VIEWs and/or STORAGE may still be specified)

 

When using TRUNCATE TABLE with CASCADE:

  • Child table referential security must specify “ON DELETE CASCADE” or the statement will fail
  • If layers of tables are referentially connected and all specify “ON DELETE CASCADE” the system will CASCADE as directed

 

Here is some example code:

 

*** Setting up sample tables ***

OOW2015 Database Manageability

This posting covers the Database Manageability sessions at OOW2015. Note that these are database manageability via Enterprise Manager, as opposed to sessions specifically covering database features and functions. The following sessions fall under this category:

OOW2015 Private Cloud and DBLM

Yesterday I posted an entry on what was coming with OOW2015, specifically discussing the Oracle Management Cloud sessions. This post is similar but looking at one of the more “traditional” EM areas that my team is responsible for – Private Cloud and DBLM. The sessions that are of most interest here are:

Delphix Express : Free version of Delphix available

Delphix Express is available!

To get a copy of Delphix Express go to

and put “Express” for your title and I’ll send you the download info.

Delphix Express is a free version of Delphix

Delphix Express differs from Delphix enterprise in that it is limited to 25 GB of managed storage.

Online Training Ad: Oracle Database 12c – New Performance Features

On 10 December 2015 I’ll give an online training entitled Oracle Database 12c – New Performance Features. This short post provides key information about it.

Description

With every new release of Oracle Database, a number of features aimed at improving performance are introduced. It goes without saying that 12.1 is no exception to the rule. Notably, it introduces key improvements in three areas.

Forget-me-nots

Here’s a little note that I drafted (according to its date stamp) in January 2013 and then forgot to post. (Which adds a little irony to the title.)

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Here’s an object lesson in (a) looking at what’s in front of you, and (b) how hard it is to remember all the details.

I ran a script today [ED: i.e. some time early Jan 2013] that I’ve have no problems with in earlier versions of Oracle, but today I was running it against 11.2.0.3 for the first time, and hit a problem with autotrace:

Controlling Execution Plans Workshop

I did a workshop at ECO 2015 today. It was a lot of fun. I’ve done numerous presentations on SQL Profiles, SQL Patches and Baselines in the past, but this session was a no-slides, hands on demo of some of the scripts I use. I also showed some scripts that can be used to re-write SQL on the fly using a new feature of 12c called SQL Translation Framework. Here is a zip file that contains all the scripts and the Controlling Executions Plans presentation that I mentioned during the workshop.

Controlling Execution Plans Workshop Zip File

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