Learning is not a spectator sport

Complete listing of posts

  • NVL vs COALESCE

    NVL vs COALESCE

    Jonathan Lewis just published a blog post about NVL and COALESCE and the optimizer costings for each. There is also perhaps a significant difference between NVL and COALESCE in that the former seems to have an in-built optimization for handling bind variables and nulls.  Consider an application where users optionally pass in search criteria and Read more

  • NULL’s vs NOT NULL’s and Performance

    NULL’s vs NOT NULL’s and Performance

    When it comes to giving the cost based optimiser the best possible chance to make the “right” decisions, many DBA’s are diligent in keeping statistics up to date, using histograms where appropriate, creating more indexes (or removing surplus indexes). However one often neglected area is that the the null-ness of columns also impacts the optimiser Read more

  • Getting started…adding an account to use

    Getting started…adding an account to use

    If you’ve read my previous post about getting started with the Oracle database, then hopefully you now have your very own database installed and running, and you have a explored a little with the sample schemas using SQL Developer.  Perhaps now you want to venture out into your own database development, and for that, you Read more

  • Those pesky LONG columns

    Those pesky LONG columns

    There was a time, many moons ago when CLOB, BLOB and BFILE did not exist as data types. So if you had anything longer than a few kilobytes of data to store, you had to use a LONG or a LONG RAW.  But those data types came with all sorts of restrictions and frustrations, and Read more

  • Identity columns in 12c … just a sequence ?

    This question came to me over Twitter, so I thought I’d whip out a quick post on it   Yes, we do implement the IDENTITY column via a sequence.  (Digression – I think this is a smart thing to do.  After all, we’ve had sequences for 20 years, so we know how they work, they Read more

  • Subtle changes in XML, 11g vs 12c

    Subtle changes in XML, 11g vs 12c

    An AskTOM reader brought this to our attention.  It is unlikely to cause you any issues, but perhaps is good to know when it comes times to upgrade from 11g to 12c. If you are taking an user defined object type and transposing that to XML, you will see a slightly different handling of NULLs Read more

  • Dealing with IP addresses

    Kris Rice made mention on Twitter about the free (but limited lifetime) IP address to Country mappings that you can get from Maxmind. If you ever need to deal with IP addresses, you might find the following utility package I wrote a while back useful.  It lets you convert from the string representation of an Read more

  • Brand new year ? Brand new to installing Oracle ?

    Brand new year ? Brand new to installing Oracle ?

    If you’ve stumbled across this blog trying to get started with a local installation of Oracle database for some personal development, then firstly, welcome! Secondly, it can be a little daunting to get up to speed, so here’s a little video that will walk though the process of download, installing and getting up and running Read more

  • Clone a table

    Clone a table

    Sometimes doing a CREATE TABLE AS SELECT is all we need to copy the data from an existing table.  But what if we want more than that ?  What if we really want to clone that table to match the original as closely as possible.  We had a question along these lines on AskTOM today.  Read more

  • Licensed for Advanced Compression? Don’t forget the network

    Licensed for Advanced Compression? Don’t forget the network

    We often think of Advanced Compression being exclusively about compressing data “at rest”, ie, on some sort of storage device.  And don’t get me wrong, if we consider just that part of Advanced Compression, that still covers a myriad of opportunities that could yield benefits for your databases and database applications: Heat maps Automatic Data Read more

  • It’s not about ego … it’s about knowledge

    It’s not about ego … it’s about knowledge

    Take a quick look at this blog post by Jonathan Lewis https://jonathanlewis.wordpress.com/2017/12/30/nvarchar2/ Anyone that has been working with Oracle for any length of time probably knows that Jonathan has a great depth of knowledge in the Oracle database, and is a regular blogger.  But this post is a good example to inspire anyone that is Read more

  • 2017–what grabbed your attention

    2017–what grabbed your attention

    Here are the blog posts that you hit on most this year.  Thanks for supporting the blog, and always, there will be more content next year ! ORA-14758: Last partition … cannot be dropped EXCHANGE PARTITION those pesky columns Pluggable database and restricted sessions Active and Inactive Sessions 12c install on Windows Problematic SQL ? Read more