Oracle Cloud Friendly – Red Samurai ADF Performance Audit

I have deployed our tool for ADF performance monitoring to Oracle Java Cloud service. It runs perfectly on the cloud, monitors slow performance and allows to analyse collected performance data. All data is stored in Oracle Database Cloud.

You can access performance monitoring dashboard using this address. Access will be available for a month or so, until my trial account will expire. You would need to use following login credentials - user: redsam, password (more...)

Complément : Analyse des performances sur du long terme

In-memory Aggregation

The title of this piece is the name given to a new feature in 12.1.0.2, and since I’ve recently blogged about a limitation of the in-memory option I thought I’d pick this feature as the next obvious thing to blog about. This is a bit of a non sequitur, though, as the feature seems to have nothing whatsoever to do with the in-memory option; instead it’s a cunning mechanism combining aspects of the star-transformation (but without the bitmap indexes), (more...)

LOB Length

It’s funny how you can make little savings in work all over the place in Oracle if you’re prepared to look a little closely at what’s going on. Here’s a quirky little example with LOBs and function calls that might just have some greater relevance in other situations. Here’s a little data set, and two queries that I might run against it:


create table tbl(
	c1      clob
)
lob (c1) store as c_lob(
	disable storage  (more...)

Scaling up Cardinality Estimates in 12.1.0.2

Topic: Counting the number of distinct values (NDV) for a table column has important applications in the database domain, ranging from query optimization to optimizing reports for large data warehouses. However the legacy SQL method of using SELECT COUNT (DISTINCT <COL>) can be very slow. This is a well known problem and Oracle 12.1.0.2 provides a new function APPROX_COUNT_DISTINCT implemented with a new-generation algorithm to address this issue by providing (more...)

Review: "WildFly Performance Tuning" by Arnold Johansson and Anders Welén

I've had the pleasure to review another book for Packt. This time it is the performance tuning guide for WildFly. Arnold Johansson and Anders Welén took a deeper look into what it takes to develop and run high performance applications on WildFly and collected a bunch of tips and tricks everybody should know.

Abstract
The hugely successful JBoss Application Server has been updated and is now called WildFly. This cutting edge technology provides a free (more...)

Oracle 12c Database In-Memory option generally available

On the 22nd of july, patchset 12.1.0.2 for Oracle 12c database was made generally available for Linux x86-64 and Solaris.

This patchset includes the eagerly awaited In-memory option which promises an application transparent performance boost by using column-format data storage in memory.

Database In – Memory uses an In-Memory column store (IM column store), which is a new component of the Oracle Database System Global Area (SGA), called the In-Memory Area. Data (more...)

Oracle Database 12.1.0.2.0 – Turning OFF the In-Memory Database option

So how to turn it the option off/disabled…As a privileged database user: > Just don’t set the INMEMORY_SIZE parameter to a non zero value…(the default...

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Being Right and Proving It

One of the great things about working in IT is that you can often win an argument simply by being right. Not because of who you are or because you are more eloquent than others, but because the facts support your position. Almost every IT person I have ever met respects facts.

In order to win arguments this way, you of course need some facts to work with. And that’s where too many people fail. (more...)

Oracle Database 12.1.0.2.0 – Native JSON Support (1)

Oracle Database 12.1.0.2 has now native support build-in for handling JSON (Javascript Object Notation) data. Oracle Database supports JSON natively with relational database features, including...

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That’s … Huge!

Recently I’ve noticed the occasional thread in Oracle newsgroups and lists asking about hugepages support in Linux, including ‘best practices’ for hugepages configuration. This information is out on that ‘world-wide web’ in various places; I’d rather put a lot of that information in this article to provide an easier way to get to it. I’ll cover what hugepages are, what they do, what they can’t do and how best to allocate them for your particular (more...)

Oracle Database 12.1.0.2.0 – New Features

The world around us is changing and new stuff in the Oracle database arena is nowadays released on patch level. Although not many new features...

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Exadata storage indexes and DML

Last week I’ve gotten a question on how storage indexes (SI) behave when the table for which the SI is holding data is changed. Based on logical reasoning, it can be two things: the SI is invalidated because the data it’s holding is changed, or the SI is updated to reflect the change. Think about this for yourself, and pick a choice. I would love to hear if you did choose the correct one.

First (more...)

New Version Of XPLAN_ASH Utility

A new version 4.1 of the XPLAN_ASH utility is available for download.

As usual the latest version can be downloaded here.

This version in particular supports now the new 12c "Adaptive" plan feature - previous versions don't cope very well with those if you don't add the "ADAPTIVE" formatting option manually.

Here are the notes from the change log:

- GV$SQL_MONITOR and GV$SQL_PLAN_MONITOR can now be customized in the
settings as table names in (more...)

B-tree and nulls

Today while I was scrolling my “WordPress reader” page I saw a post which reminds me to something I had fun before /and find it useful in many situations/: So if we have an index based on null column followed by not null column we can use it to filter the rows with null value. […]

FIRST_ROWS_n Optimizer Mode – What is Wrong with this Statement?

June 8, 2014 It has been nearly two years since I last wrote a review of an Oracle Database related book, although I have recently written reviews of two Microsoft Exchange Server 2013 books and a handful of security cameras in the last two years.  My copy of the second edition of the “Troubleshooting Oracle […]

Tab Navigation Performance in UI Shell and Multi Task Flow

I was investigating performance impact of navigating between tabs in UI Shell template. To compare, as alternative solution for UI Shell, I was using dynamic tabs with Multi Task Flow binding (Building Custom UI Shell with ADF 11g R2). When you switch between tabs in UI Shell, you could notice slight delay. This is normal delay (differently to browser tabs, where no delay), as there should be generated response from the server and (more...)

Unindexed foreign keys

Unindexed foreign keys can lead to bad database performance due to lock contention and full table scans performed on the child table. Here is a diagram which illustrate the situation: In this exemple Oracle needs to lock the entire employees table when the primary key of the departments table is modified, in addition to that [...]

The post Unindexed foreign keys appeared first on Oracle DBA Scripts and Articles (Montreal).

Simora: Alpha Testers Confirmed

It's been a while since I provided any public updates regarding Simora, our Oracle workload simulation product. It's finally time to unveil the status of Simora and our steps moving forwards. We have been working extensively on the Simora engine and infrastructure over the  last several months, with a view to transforming it into a […]

SQL Activity for the last hour

This script can be used to show the top 10 SQL activity for the last hour. It uses the v$active_session_history view to search top SQL by resource consumption. SQL Activity [crayon-5377b1876b186473467355/] Here is the result you can obtain: and the active sessions history graph for the same period:

The post SQL Activity for the last hour appeared first on Oracle DBA Scripts and Articles (Montreal).