Igor's Blog

26-Mar-2017
WebLogic package-name element classpath generator script
I wrote a post a few days ago about using Jersey 2.x as a shared library with WebLogic 12.1.2. In that post I suggested the following: In weblogic.xml the prefer-application-packages element needs to have entries added for ALL OF THE PACKAGES in the Jersey 2.x shared library JAR files. That means you need to go through every jar file in WEB-INF/lib for the shared library that was created with Maven and make sure the packages it defines are included in this element.
22-Mar-2017
Using Jersey 2.x as a shared library on WebLogic 12.1.2
WebLogic 12.1.2 may not be listed on Oracle Technology Network Downloads page but it is still being used. When it comes to RESTful services on WebLogic, 12.1.2 supports Jersey 1.13 so if you're looking to make use of Jersey 2.x features, there's some extra work to be done. With 12.1.3 you can go straight for Jersey 2.x but that's outside the scope of this article.
17-Oct-2016
Automatically insert a UUID value into a table with Oracle
There are different approaches to inserting a UUID into an Oracle Database table, ranging from Java to various ways of doing it in PL/SQL (as described here). Not many of these seemed appealing to me so I came up with my own approach using a trigger.
01-Oct-2016
Using Maven to create a super SQL file with the merge-maven-plugin
If you've ever worked on a PL/SQL project or any project with a good amount of database related work you probably have had to deal with multiple SQL files and their deployment across systems. This is exactly what I've come across recently. Even in the early stages of my PL/SQL project I had 11 separate SQL files that would need to be deployed to system and performance test environments, then propagated to production, production support, etc. To help with managing all this I decided that building a single 'super SQL' file would work best and I ended up using Maven to do it.
13-Jun-2016
MySQL always returning 0.999 for DECIMAL type fields
I've started to use the DECIMAL type in MySQL to store longitude/latitude coordinates recently and for some reason no matter what value I stored, when queried back I'd always get '0.999'. A little bit of investigation and I found the answer so lets see what was going wrong.
27-May-2016
How to get orapki without installing the full Fusion Middleware
I was asked recently if there was a way to get the orapki utility without having to install the entire Fusion Middleware. The answer is yes, sort of. So if you need access to this utility but for some reason are not able to use the one that comes with your application server, read on.
10-May-2016
Java Mission Control requires GTK but which version?
I've recently had one of the DBAs on a project ask me what GTK version is required to run Java Mission Control with JDK 7. I thought easy, the documentation should tell me this, but after searching for several hours I've come up with nothing, apart from 'GTK Libraries Required' as stated in the Oracle Java Mission Control 5.3 Certified System Configurations.
30-Mar-2016
Getting around the 'ORA-01840: input value not long enough for date format' error
An issue has been brought to my attention recently that was to do with the to_date function returning an ORA-01840 error for certain values. This prompted an investigation which ultimately proved that it was a data issue, however I decided to put together a workaround for future reference anyway.
30-Mar-2016
Example JAX-WS WebService built with Oracle WebLogic Maven plugin (wsgen)
In the past I've shown how to use Ant and the JWSC task to build a JAX-WS web service, well I've moved onto Maven now and started to use the Oracle WebLogic Maven plugin to build services. This is an example on how to build a JAX-WS web service using that plugin, specifically the wsgen goal.
20-Mar-2016
Returning compressed MTOM data with JAX-WS DataHandler
A while back I've shown an example MTOM/XOP enabled web service using DataHandler. Although MTOM is great for optimising the output of a web service, sometimes it's just better to compress these results before sending them.
16-Mar-2016
Oracle WebLogic Maven plugin fails on the JWSC goal for certain uses of unchecked generics
The Oracle Maven Plugin is great and provides very useful functionality like the ws-jwsc goal that compiles your JWS file into a deployable web service. However, in some situations I noticed that JWSC cannot handle unchecked generics. I did find a way to fix it so read on.
15-Mar-2016
Oracle Database XMLTable vs ExtractValue performance
I've been doing SQL optimisation for some of the services at work recently and saw that we've been using EXTRACTVALUE in a number of places. This is not bad in itself, however the Oracle 12c documentation states that EXTRACTVALUE is deprecated and should be replaced with XMLTABLE.
07-Mar-2016
Specifying a default namespace with XMLTABLE
I really like the Oracle XMLTABLE feature, which allows you to treat an XML string as if it were a real table. I've been using this feature quite a bit lately and had some difficulties initially around the default namespace so I thought I'd share my findings.
02-Mar-2016
Howto: Force null values to be highlighted in SQLDeveloper query results
I've written previously about a neat highlighting feature that SQL Developer has in a post about navigational filtering. There is another feature that is just as handy that allows you to automatically highlight all (null) values in the query results. This of course makes it very easy to see nulls at a glance and definitely eases the task of examining results for specific patterns.
17-Feb-2016
When null == null isn't true and how to get around it
I've been writing some tricky SQL recently and came across an odd behaviour, at least I though it was odd at the time because I didn't read the documentation. I had two columns that represented a composite key, the first column was guaranteed to have a value and the second column could be null. Now I had to join this table to itself to get the results I needed and that required comparing this composite key. When I compared just the first column it worked fine, but as soon as I added the second column, the one that could have null values, nothing matched.
27-Jan-2016
Use SQLDeveloper navigational filtering to unclutter your workspace
SQL Developer is a great tool and it gets better with every version, well in version 4 I noticed that you can filter out what is displayed in the tree underneath a database when you have successfully connected. If you don't exactly know what I mean, this would probably be a familiar sight...
23-Jan-2016
How to redirect SQLDeveloper debug log to a file
I've come across an excellent article by Jeff Smith recently that describes how to enable debug mode in SQL Developer. This has been a useful source of information in my recent quest to solve some connectivity issues with certain databases, however it wasn't the final answer I was after.
20-Dec-2015
The correct way to bind variables with a LIKE clause in SQL and Java
I was a bit stumped by this one not long ago so here is an example of correctly binding a value to a LIKE clause inside a SQL statement with Java.
07-Dec-2015
Maven WebLogic Plugin and the Java 5 source code bug plus how to fix it
I've noted previously that the JWSC Ant Task fails to build Java sources above 1.5 source version due to a hardcoded "1.5" value in one of the Jar files. That was happening for the 12.1.2 version of the Ant task, it also appears to be a problem in the 12.1.2 Maven plugin as well as the 12.1.3 Maven plugin.
14-Jun-2015
Visualising Oracle database partition data distribution with gnuplot
We use partitioning in at least one of the databases at work, changing to partitioned tables has allowed us to keep the system running within our imposed SLAs. Recently I've started to wonder however, what happens when we start hammering individual partitions more than others. The data distribution would be skewed and the benefits of partitioning lost. I decided to put together a bit of SQL and then use gnuplot to show me how well our data is distributed.
15-May-2015
Fixing the 'weblogic.transaction.nonxa.NonXAException: IO Error: Connection reset' error
One day my web services were working fine, the next I started getting the 'weblogic.transaction.nonxa.NonXAException: IO Error: Connection reset' error every time I tried to run some code that queried the database. This struck me as odd because the same code worked on a different environment.
05-May-2015
Change the JRE used for SoapUI on OSX
I use SoapUI on a regular basis and today I wanted to change the JDK that it uses. I've noticed that by default the OS X installation of SoapUI 5.1.2 is using JRE 1.7. On my system, I've had the 1.8 JDK set as the default for quite some time, my ~/.profile file pointed to the 1.8 JDK bin directory for the PATH and the JAVA_HOME was set correctly, so it was puzzling to me why 1.7 was being picked up by SoapUI. I dug a little deeper and found the answer.
18-Mar-2015
SQLDeveloper bug not showing PL/SQL procedures that have no input parameters
We've updated some of our databases to 12c recently, at the same time I was working on an issue in some of the PL/SQL packages that I've built and running some tests on these. To my surprise when I tried to run my test PL/SQL procedure, SQL Developer was not showing in its run dialog.
18-Feb-2015
Workaround for JDeveloper 12c Refactor Rename bug
I use JDeveloper on an almost daily basis and when something as basic and fundamental to the product as the rename functionality breaks, it makes you want to tear your hair out. I'm talking about the Refactor Rename feature that has been broken since the 12c release. Luckily there is a workaround.
11-Dec-2014
error: ORA-29494: invalid state for run task when calling dbms_parallel_execute create_chunks_by_number_col()
I've been updating some of my previous PL/SQL scripts at work only to notice during my testing that I was getting the error: ORA-29494: invalid state for run task error when I tried to run certain tests. This had me stumped for a while because none of the functionality that was to do with chunking was changed. Turns out I was just doing something stupid, here's what happened.
08-Sep-2014
WebLogic 'Unresolved reference to WseeJaxwsFileStore' error after extending a domain with ADF 12c
Recently after installing ADF 12c and extending my domain to support ADF applications, I could no longer start my managed server. The 'Unresolved reference to WseeJaxwsFileStore' error kept on coming up every time I'd try to start the server.
03-Sep-2014
Making ADF af:table emptyText appear with padding using some CSS
I've been doing a fair amount of ADF work recently and especially dealing with tables. What I found was that when a table contained no data, the emptyText string rendering is very ugly by default, so I got exploring. It turns out you can put HTML into this string and customise how it is rendered with some CSS.
26-Aug-2014
JDeveloper 11g to 12c ADF Application migration causes deployments to fail with a ClassNotFoundException
I've been porting an older ADF 11g application to ADF 12c and used JDeveloper to do the migration for me, after a bit of code tweaking I tried to deploy the app only to find that it was failing with the java.lang.ClassNotFoundException: org.apache.myfaces.trinidad.webapp.TrinidadConverterELTag error. It took some time to find the culprit, so I've decided to share the fix.
05-Aug-2014
Log request service times in Oracle Application Server 10gAS (10.1.3.x) with SSL enabled
Recently I was asked to investigate how long our web service requests were taking to process at the level of the application server. We had logging inside the web services for total elapsed time serving a request, but we wanted to see if there was any overhead within the app server. Our app server is 10gAS with Apache 1.3 as the web tier.
05-Aug-2014
Safari can't verify the identity of the website "login.oracle.com"
Looks like Oracle's VeriSign certificate has expired and hasn't been replaced. The Symantech SSL Toolbox is reporting the website as insecure. This means every time you want to login to Oracle Support, you will get an expired certificate error.
23-Jul-2014
NetBeans 7.1.2 does not work with JDK 8
I've recently installed the JDK 8 on my rMBP and all of a sudden NetBeans stopped working for me. I've dug into this a little further and tried several things, none of which worked, in the end I ended up forcing NetBeans to use JDK 7 and everything was working again.
20-Jun-2014
Use hightlights in SQLDeveloper to instantly see patterns in data
So I've been using SQLDeveloper like mad lately and have been finding some really neat features that it provides. One of the great time savers is its ability to create persistent highlights that you can use to instantly see the patterns in data. Great for debugging that ETL!
13-Jun-2014
The dbms_parallel_execute.create_chunks_by_rowid not creating enough chunks, bound by extents
This post is about an Oracle 11gR2 feature. I've been using the dbms_parallel_execute PL/SQL package to parallelise processing of large amounts of data and ran into some issues with chunking of my processing table. What I've noticed is that the number of chunks created seemed to be bound by the number of extents that the table was using, this was not ideal in my case, luckily there is a different solution to create as many chunks as you need.
11-Jun-2014
SQLDeveloper 4.0.2 on OS X with the Mac L&F rendering issues
I've updated my SQLDeveloper to 4.0.2 and to my surprise found a major rendering issue with this version. The whole window is using black as the background, including the toolbar. This means none of the text can be read and the whole application is essentially useless then.
20-May-2014
Tuning the SQL*Plus fetch size for better performance
I've been doing a fair amount of work with data extraction from a database to a flat file recently using SQL*Plus and have been looking at ways to speed up the process. This is where the arraysize setting comes in handy. This setting controls how many rows are fetched from the database in a single round trip. I did some testing with various sizes and found that tweaking this value can have huge performance improvements. This is what I found with the data I was extracting.
06-Jun-2013
ADF 10g Aligning a form Submit Button to the input fields
For a very simple task of aligning a button to the input fields on the rest of the form, in ADF 10g it is quite a painful process. It took me a bit of experimentation to get it working correctly, but here is the result.
04-Jun-2013
Stand alone CSF (Credential Store Framework) example
I've been trying to figure out the Oracle CSF 11g documentation over the last couple of days without getting very far. The documentation is a bit incomplete and has errors in it (referencing classes that do not exist for example). So since I had to implement this for the project I am on, I had no choice by to figure it out myself.
12-Feb-2013
Killing runaway SQL sessions in Oracle
I've been running a lot of SQL recently that would sometimes get 'stuck' due to the optimiser picking a plan with a full table scan. On a small database this may not be a problem, but when the database has billions of rows and a full table scan that pulls in 100Gb+ of data, the wait is long.

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WebLogic package-name element classpath generator script

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Workaround for Mobile Safari scrollTop() not updating during scroll

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