presentation (and book
), I have created a presentation called PL/SQL: The Good Parts
This is not intended as an introduction to PL/SQL, but rather an overview of features you should consider if you want to maximize your enjoyment of programming in the Oracle Database. Also, this is not an exhaustive list of all features, it's simply the ones I personally use frequently.
Note that unlike (more...)
I ran into a problem the other day when moving some code from one database to another (both XE 11g). The code in question needs to convert an XMLType to a CLOB to do some (hacky) string manipulation on it, and then turn it back to an XMLType.
Here's the original code: l_xml := apex_web_service.make_request(...);
-- little hack to remove bad empty namespace from result
l_clob := l_xml.getClobVal();
In looking for information on pivoting variable number of columns, I stumbled across a question I once managed to AskTom, many moons ago.https://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:7644594042547
Adrian Billington has an interesting lead into an XML solution with pivot, but would need more digging to finalise conversation of XML data for APEX to use.http://www.oracle-developer.net/display.php?id=506
Then I found Tom's answer using easy to understand dynamic SQL (properly asserted, no less)https://asktom. (more...)
Have you ever, like me, been silently finger-counting the number of characters in a table name, column name or procedure name that you are about to create in the Oracle Database, to make sure it is short enough? It appears those days will soon (?) be at an end...
The current limit on names (identifiers such as table names, column names, procedure names, parameter names, etc) in Oracle SQL and PL/SQL is 30 characters. (more...)
Recently I showed simple example how result_cache works with non-deterministic functions and observed strange behaviour: a function gets fired once in the normal query, but twice with the result_cache hint.
Moreover, only third and subsequent query executions return same cached results as second query execution.
I didn’t want to investigate such behavior, just because 1) we should not cache the results of non-deterministic functions and 2) it doesn’t matter if we use deterministic functions.
One of my pet-projects is LoggerUtil, which is a utility for Logger, which is an excellent logging tool for PL/SQL.
This post is not about Logger, but some dealings with Conditional Compilation.
With Conditional Compilation you can create a single code base to handle different functionalities depending on compiler flags.
The latest addition to LoggerUtil was a method to create a custom template. For this to work, LoggerUtil depends on a certain Logger Release (where (more...)
Virtual Columns are really cool. I like them a lot. If you've never heard of them, shame on you, learn about them.
In short: a Virtual Column is not a real column, it's an expression that looks like a column... more or less.
While using the Virtual Columns, we ran into a little oddity with them.
First of all let's start with the version of the database that I tested this on. Yes, I know (more...)
Since I have written about my pet project about a month ago, I have made some major changes to the functionality of it.
If you haven't read that blog about my pet project, here's the synopsis:
I love Logger to instrument my code, I just don't like to type in all the bits and pieces to register all the input arguments when I write a new procedure or function. To solve this problem I have (more...)
The article read most often on this blog is called "Splitting a Comma Delimited String, the RegExp way".
On this blog there are two articles about this technique, one is about splitting up a single string into multiple rows and the other is about multiple strings into multiple rows.
Links to both articles are included at the bottom of this article.
It seems like there is a need for functionality like that frequently. And just (more...)
Execution Plan Instability – What is the problem?
The Oracle Optimizer is a complex piece of software and with every release it becomes more complex.
In the beginning, the Optimizer was rule-based.
The Optimizer had a ranked list of heuristics used to optimize a query, picking the lowest ranked rule available.
This rule-based mode, whilst still in use with some internal Oracle dictionary queries, has been unsupported since version 10.1.
This means that (more...)
To refresh multiple Materialized Views you can use the DBMS_MVIEW package, with the procedure aptly named Refresh. One method is to provide a comma-separated list of Materialized View names, or you can use an DBMS_UTILITY.UNCL_ARRAY to achieve the same objective.
When using the latter method, I stumbled upon this oddity (which is not in the current documentation, or at least I couldn't find it).
The procedure that I initially wrote was the following:
Instrumentation of PL/SQL code is essential. My favourite tool to instrument PL/SQL is Logger.
Martin Giffy D'Souza wrote a few blogs on how to speed up development with Logger and I want to chime in with my own productivity booster.
What I have written is a PL/SQL package that will generate a Procedure or Function body with all the calls to Logger. This includes all the arguments, or at least the IN and IN/OUT arguments.
Recently someone asked me: "How did you do that? When I include an APEX page in a Page Group, the correct tab is automatically highlighted"
When I setup an application, I usually use Dimitri Gielis' method,
so instead of using "real tabs", I use a List and display that list as Tabs.
For each of the "Tabs", I also create Page Groups, just to keep things organized.
Each of the List Entries will have a (more...)
The PL/SQL Utility Library, codenamed "Alexandria", now has a new home at GitHub
. This will make it easier to collaborate on the project. If you want to contribute, just fork and submit a pull request.
The liibrary contains around 50 PL/SQL packages as well as a few types. There are no table dependencies, which reflects the general-purpose nature of the utilities. Jeffrey Kemp has a great guided tour of the library
which highlights some of (more...)
It seems impossible to raise an exception when handling no_data_needed.
create or replace function demo return sys.odciNumberList pipelined
exception when others then
dbms_output.put_line('in exception handler, sqlcode: ' || sqlcode);
firstname.lastname@example.org > select * from table(demo());
ORA-06501: PL/SQL: program error
ORA-06512: at "SOKRATES.DEMO", line 8
ORA-01476: divisor is equal to zero
no rows selected
in exception handler, sqlcode: -1476
If you want to be able to create contemporary high-performing PL/SQL code, welcome to my training event in NYC (hosted by NYOUG) on November 7, 2014:
I think, it is as important as ever to follow best practices for server-side development. There are lots of options that could get the job done "now", but very few that would survive for months/years. Also, there is a constant pressure from various "alternative" solutions to (more...)
My session on "Oracle 12c for Developers" is done.Afterwards someone asks the question:
What happens when you use DBMS_REDACT with a complete row update?
My guess was that it would place the redacted data in the column, but I haven't tried it, so here goes:
create table emp
,to_char (abs (dbms_random.random)) credit_card
(object_schema => 'A'
,object_name => 'EMP'
,policy_name => 'Hide Creditcard'
It seems to me that I talked about my most recent book everywhere except for my own blog... So, let me introduce you a one and only performance tuning book dedicated to PL/SQL
This book took me much longer to write than I initially anticipated - and to be fair, that's the reason for staying quiet at the blog. I just didn't have time/energy to write everywhere :-) Although, it was fun writing - (more...)
The EOUC (EMEA Oracle User Group Community) hosts a special session on sunday during Oracle Open World. This session contains twelve things about Oracle 12c. Each of these 12 things is hosted by a different speaker, so this means that each section is only five minutes long (Strictly guarded by Debra Lilley).
Thankfully I was chosen to be one of the speaker during this special session, very excited and also very scared. (more...)