October 2017

Best method for tuning sub-optimal execution plans

How do you determine if the Oracle SQL optimizer has created a sub-optimal execution plan? re-run statistics and see what happens? wait for Oracle to fin other execution plans? What if neither method is helping? Do you read the execution plan? What do you look at? Differences in actual vs estimated? How successful is that? Look for full table scans?  Do you look at the 10053 trace? How much time and effort does that take?  What do you look at in the 10053 trace. Do you have a systematic methodology  that works in almost all cases?

Well there is a method that is reliable and systematic. It’s laid out inDan Tow’s book SQL Tuning.

Oracle C functions annotations

Warning! This is a post about Oracle database internals for internals lovers and researchers. For normal, functional administration, this post serves no function. The post shows a little tool I created which consists of a small database I compiled with Oracle database C function names and a script to query it. The reason that keeping such a database makes sense in the first place, is because the Oracle C functions for the Oracle database are setup in an hierarchy based on the function name. This means you can deduct what part of the execution you are in by looking at the function name; for example ‘kslgetl’ means kernel service lock layer, get latch.

To use this, clone git repository at https://gitlab.com/FritsHoogland/ora_functions.git

nVision Performance Tuning: 1. nVision Performance Options

This blog post is part of a series that discusses how to get optimal performance from PeopleSoft nVision reporting as used in General Ledger.

At no point when defining a nVision report does the developer directly specify a SQL statement, all the SQL is generated by nVision from the report definition.  That also means that it is not possible to directly intervene and change the SQL statement, for example, to add an optimizer hint.

However, the way that the SQL is generated can be controlled via the nVision performance options. Setting this appropriately can make a significant difference to nVision performance, but the optimal settings will differ from system to system, from tree to tree and sometimes even report to report.

Linux for the SQL Server DBA- Part I

For the Oracle DBA, Linux is life.  When I was at Oracle, Linux projects were the easy part of my job, unlike the ones on Windows, AIX, HP-UX and at times, even Solaris.  You knew the Linux ones received the most love from development, had the most time towards patching and received attention if there was a bug.

Idle banter

When your car gets a flat tyre, it’s always handy to have a spare.  We do the same with the database Smile

Buzzword Bingo

Looking for that catchy title for your next presentation ?

I took the first word from the title of 1000 Oracle OpenWorld presentations, and looked for patterns Smile.  I omitted some obvious terms that are either products or definite/indefinite articles:

  • Oracle
  • Peoplesoft 
  • The
  • How 
  • OAUG
  • General
  • MySQL

And here is what we end up with:

OpenWorld 2017–grab ALL of the content

Some people use the session catalog to grab just the presentations that they either attended, or could not attend.

Other people want a download of every available presentation so they can peruse the entire catalog offline at a later date.

I am one of the latter people. Smile

So using some node, javascript, awk, sed, grep I managed to data-mine the catalog page to come up with a list of uploaded presentations in the form:


wget --no-check-certificate -O "SessionTitle".extension "https://static.rainfocus.com/full_path_to_presentation.extension"

which of course can then be run as a batch file to grab them all. Woo hoo !!!

How Much Availability is Enough

  

At Oracle OpenWorld 17, Larry Ellison announced “Oracle Autonomous Database Cloud” and “Oracle Autonomous Data Warehouse Cloud”.     Among other features, Oracle guarantees these databases will have an SLA of 99.995% or less than 30 minutes of “costly planned and unplanned downtime” a year.

For applications that require that level of availability, this sets a very high bar.  However, this sort of availability comes with a cost; and not all applications require this level of availability.   In this blog, I’ll offer some suggestions on how to determine the correct levels of availability for your applications, and suggest some ways you can obtain those levels, at significantly less cost and complexity.

In memoriam – 3

My father-in-law died a couple of weeks ago, aged 95. This is the story that he wrote for his children and grandchildren a few years ago describing his experiences as a Naval engineer on the aircraft carrier HMS Indefatigable during the second world war.