OraNA :: Oracle News Aggregator

Some time ago – actually a few years ago – I wrote a note about the hint /*+ gather_plan_statistics */ making some informal comments about the implementation and relevant hidden parameters. I’ve recently discovered a couple of notes from Alexander Anokhin describing the feature in far more detail and describing (more...)

Writing log records

The last post in this series introduced the problem briefly. You find that post here.

In this post I’ll talk about the changes made to make that writing of log records fast enough. There were 50 million records that was written. Each of them pretty much in its (more...)

Obligatory Melodrama

No matter how much time goes by I still remember it. The day my database was crippled beyond reckoning. That moment when I saw my hopes for a bright and shining future with my database spill through my fingers like so many cracker crumbs falling on a clean (more...)

Introduction

In my work among other things I tune and tweak solutions for EXADATA. Today I’ll write about a big improvement we achieved with a process that moves data from the operational tables to the ones where the history is stored.

This will not be a technical post. While I (more...)

Carlos Sierra:

Since lack of Histograms or freezing CBO Statistics do not guarantee Plan Stability, do not rely on these two myths. If what you are looking for is Plan Stability use then SQL Plan Management available since 11g or SQL Profiles available from 10g.

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© Eddie Awad's Blog (more...)

Dominic Brooks published a note recently about some very nasty SQL – originally thinking that it was displaying a run-time problem due to the extreme number of copies of the lnnvl() function the optimizer had produced. In fact it turned out to be a parse-time problem rather than a run-time problem, (more...)

Topic: This post is about the use of heat maps to investigate wait event latency in Oracle (and in particular I/O-related latency). This post also discusses a SQL*plus-based script/tool I have developed to help with this type of monitoring and performance drill-down (OraLatencyMap).

Context: Oracle (since version 11gR1) exposes (more...)

A new major release (version 3.0) of my XPLAN_ASH tool is available for download.

You can download the latest version here.

In addition to many changes to the way the information is presented and many other smaller changes to functionality there is one major new feature: XPLAN_ASH now also (more...)

Anyone who has used Kevin Closson’s “Silly Little Oracle Benchmark” will want to know about his significantly updated SLOB2.

This might be something very obvious for the reader but I had an interesting revelation recently when implementing parallel_degree_limit_p1 in a resource consumer group. My aim was to prevent users mapped to a resource consumer group from executing any query in parallel. The environment is fictional, but let’s assume that it is (more...)

Note: This post is about diagnosing real life scenario caused by  direct path decision change on 11.2.0.3 which already covered  by Tanel Poder on his awesome Optimizer statistics-driven direct path read decision for full table scans (_direct_read_decision_statistics_driven) post
If you already read and know how to (more...)

Here's part two!

I just got permission from The UK Oracle Users Group to reproduce my article series on optimising scans in Oracle. Part One is available here, Part Two will follow shortly after, and then Part Three will be a few weeks away, following its publication in the magazine. Enjoy!

In my adventures in Twitterland I’ve noticed a lot of people who are using WordPress blogs (this one included). Some use wordpress.com which gives them a free blog with minimal theme and plugin choices; however, they (more...)

The nmon (Nigel’s Monitor) tool was written initially for AIX to monitor system performance, but there are plenty of distributions available now so people can use it on a variety of operating systems these days, including flavours of Linux and even the recent Raspberry Pi (mini ARM based computer). It’s one of (more...)

Hierbij nog dank voor allen die aanwezig waren bij de weer gevulde, informatieve & gezellige avond tijdens “Hotsos Revisited 2013″. Wij presentatoren hebben genoten van het ambiance. Hier ook nog voor degenen die graag het nog een keer willen nalezen het presentatie materiaal van Toon, Jacco, Gerwin, Frits en mij… (more...)

AMIS is spending a lot of effort keeping our people up-to-date with the latest knowledge needed to help our customers the best way we can. Traditionally we also always try to share our knowledge with customers and others, via social media or conferences, and while abroad learning from others at the same time. It is …

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