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March 2015

Oracle Database In-Memory Test Drive Workshop: Canberra 28 April 2015

I’ll be running a free Oracle Database In-Memory Test Drive Workshop locally here in Canberra on Tuesday, 28th April 2015. Just bring a laptop with at least 8G of RAM and I’ll supply a VirtualBox image with the Oracle Database 12c In-Memory environment. Together we’ll go through a number of hands-on labs that cover: Configuring the Product Easily […]

Sqlplus is my second home, part 8: Embedding multiple sqlplus arguments into one variable

I’ve updated some of my ASH scripts to use these 4 arguments in a standard way:

  1. What ASH columns to display (and aggregate by)
  2. Which ASH rows to use for the report (filter)
  3. Time range start
  4. Time range end

So this means whenever I run ashtop (or dashtop) for example, I need to type in all 4 parameters. The example below would show top SQL_IDs only for user SOE sessions from last hour of ASH samples:

Video Tutorial: XPLAN_ASH Active Session History - Part 4

#333333; font-family: Verdana, Arial, sans-serif; font-size: 13px; line-height: 16.8999996185303px;">The next part of the video tutorial explaining the XPLAN_ASH Active Session History functionality continuing the actual walk-through of the script output.
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#333333; font-family: Verdana, Arial, sans-serif; font-size: 13px; line-height: 16.8999996185303px;" />#333333; font-family: Verdana, Arial, sans-serif; font-size: 13px; line-height: 16.8999996185303px;">More parts to follow.
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In-memory – can you REALLY drop those indexes ?

Its not a hard sell to convince anyone that a whopping huge great chunk of compressed column-based memory is going to assist with those analytic-style queries.  The In-memory option seems a natural fit, especially for those people where the bottleneck in their infrastructure is the capacity to consume data from storage.

What perhaps a more interesting area of investigation is the claim that In-memory will also be of benefit in OLTP systems, where (to paraphrase many presenters at OpenWorld 2014), we wont be needing all those indexes on transactional tables.

So I thought I’d have an initial play around in that space, and see what happens.

We’ll start with a simple test bed – a transactional table "T", being a child of parent table "PAR",  with a few indexes representing those "additional" OLTP indexes.

ANSI expansion

Here’s a quirky little bug that appeared on the OTN database forum in the last 24 hours which (in 12c, at least) produces an issue which I can best demonstrate with the following cut-n-paste:

ASH

There was a little conversation on Oracle-L about ASH (active session history) recently which I thought worth highlighting – partly because it raised a detail that I had got wrong until Tim Gorman corrected me a few years ago.

Once every second the dynamic performance view v$active_session_history copies information about active sessions from v$session. (There are a couple of exceptions to the this rule – for example if a session has called dbms_lock.sleep() it will appear in v$session as state = ‘ACTIVE’, but it will not be recorded in v$active_session_history.) Each of these snapshots is referred to as a “sample” and may hold zero, one, or many rows.

PowerPoint 2013 Always Starts Minimized

This post has nothing to do with Oracle or Enterprise Manager at all, so if that’s all you’re interested in you can stop reading now. :)

Yesterday I ran into the situation where PowerPoint would only open minimized on the task bar and nothing I could do would get it to budge from there. The only way I could get PowerPoint to start and be displayed on any monitor was to start it in safe mode. [As an aside, to start PowerPoint (or indeed any Office product) in Safe Mode you just need to hold down the Control key while double-clicking either the PowerPoint program or any PowerPoint document.] After starting PowerPoint successfully in Safe Mode, I could see PowerPoint on my screen, but when I closed it down and tried to restart in normal mode, it would always start minimized.

Who Plans The Content of UKOUG Tech15?

<..Who are the Tech15 committee and my role
….submitting an abstract..>

When you go to a conference like UKOUG Tech15 there are hundreds of talks given over several days and a dozen or so streams. Who decides what is presented and how do they decide?

12c MView refresh

Some time ago I wrote a blog note describing a hack for refreshing a large materialized view with minimum overhead by taking advantage of a single-partition partitioned table. This note describes how Oracle 12c now gives you an official way of doing something similar – the “out of place” refresh.

I’ll start by creating a matieralized view and creating a couple of indexes on the resulting underlying table; then show you three different calls to refresh the view. The materialized view is based on all_objects so it can’t be made available for query rewrite (ORA-30354: Query rewrite not allowed on SYS relations) , and I haven’t created any materialized view logs so there’s no question of fast refreshes – but all I intend to do here is show you the relative impact of a complete refresh.

Try Oracle 12c VM with Delphix download


9104210308_a63b5ae5c4_z
 photo by #212124;" title="Go to Jose Maria Cuellar's photostream" href="https://www.flickr.com/photos/cuellar/" data-track="attributionNameClick" data-rapid_p="67">Jose Maria Cuellar (CC 2.0)

Thanks to Leighton Nelson who pointed out  that :

Oracle has a pre-installed Linux VM with 12c

Delphix as well has a pre-installed   trial version