During a trial run for my presentation at Oracle Open World "Oracle 12c for Developers", you can find the slides on slideshare. there was a question regarding "Temporal Validity".
What is Temporal Validity?
The documentation says it best:
Temporal Validity Support lets you associate one or more valid time dimensions with a table and have data be visible depending on its time-based validity, as determined by the start and end dates or time stamps of (more...)
In seinem Blog hat Jonathan Lewis
dieser Tage die Quizfrage gestellt, wieso es möglich ist, dass eine Query mit einer Einschränkung der Form:
where col1 between 1 and 3
durch eine Umwandlung der Bedingung in die folgende Form optimiert werden kann:
where col1 = 1 or col1 > 1 and col1 <= 3
Die Antwort lautet (natürlich): durch die Kombination mehrerer Zugriffsmöglichkeiten - im Beispiel, an das der Herr Lewis gedacht hatte, geht es um (more...)
Once you are able to show the xml version of the alert log as data in database table Alert_XML, it would be nice to checkout the errors with accompanying timestamps from within view Alert_XML_Errors. Like this, with the help of 2 types and a pipelined function.
su - oracle
. oraenv [ orcl ]
[oracle@localhost ~]$ sqlplus harry/*****
SQL> desc alert_xml
Name Null? Type
----------------------------------------- -------- ----------------------------
TEXT VARCHAR2(400 CHAR)
SQL> CREATE OR REPLACE (more...)
12c gave us two new features among others: DBMS_UTILITY.EXPAND_SQL_TEXT and temporal validity. DBMS_UTILITY.EXPAND_SQL_TEXT is advertised as a means to expand SQL text that is using views, but it is also very useful to see how Oracle internally rewrites some SQL queries. Here I'm going to use it to see how temporal validity queries are actually executed. All tests are done using 126.96.36.199 Enterprise Edition.
First I'll create a table for (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...)
By mapping an external table to some text file, you can view the file contents as if it were
data in a database table. External tables are available since Oracle 9i Database, and from Oracle
11gR2 Database on, it is even possible to do some inline preprocessing on the file.
The following example of this feature picks up on standard output of shell script “get_alert_xml.sh”.
It isn’t referencing any file, but take notice of (more...)
A quick post to let you know about the two presentations that I’ll be doing at Oracle Open World 2014.
Session ID: UGF4482
Session Title: “Getting Started with SQL Pattern Matching in Oracle Database 12c“
Venue / Room: Moscone South – 301
Date and Time: 9/28/14, 13:30 – 14:15
Session ID: CON4493
Session Title: “Regular Expressions (more...)
While preparing for my session at Oracle Open World on "Oracle 12c for Developers" I ran into a little remarkable thing.
When sorting a dataset, the sorting is always done last. That is what I was taught anyway. There is probably some obscure way to detect the exact execution plan, but personally I never bothered to go and investigate.
When I was created some test scripts I found there was a way to see that (more...)
A comparison of sucking data into a table over a db link using DBMS_PARALLEL_EXECUTE.
This particular example is based on something I needed to do in the real world, copying data from one database into another over a db link. Datapump is not available to me. Tables in question happen to be partitioned by a date-like number (boo!) hence some of the specific actions in the detail.
I think it’s a good example of (more...)
A couple of years ago I posted a simple example using PIVOT
, converting rows to columns with the classic example of figures by months.
Oracle 11g R1 also introduced the UNPIVOT
function, allowing columns to be converted into rows.
I've created an example that lists cities by row, but two attractions as two columns, with pairing attributes describing the reason for the attraction.
create table aus_attractions(id number, city varchar2(50)
, attraction1 varchar2(50)
A recent addition to my Oracle PL/SQL library is the book Oracle PL/SQL Performance Tuning Tips & Techniques by Michael Rosenblum and Dr. Paul Dorsey.
I agree with Steven Feuerstein’s review that “if you write PL/SQL or are responsible for tuning the PL/SQL code written by someone else, this book will give you a broader, deeper set of tools with which to achieve PL/SQL success”.
In the foreword of the book, Bryn Llewellyn writes:
Steven Feuerstein was dismayed when he found in a PL/SQL procedure a cursor FOR loop that contained an INSERT and an UPDATE statements.
That is a classic anti-pattern, a general pattern of coding that should be avoided. It should be avoided because the inserts and updates are changing the tables on a row-by-row basis, which maximizes the number of context switches (between SQL and PL/SQL) and consequently greatly slows the performance of the code. Fortunately, (more...)
In my previous blog post I gave some PL/SQL that performed the tokenising of a string. Check out this blog post here.
Thanks also to the people who sent me links examples of how to tokenise a string using the MODEL clause. Yes there are lots of examples of this out there on the interest.
While performing the various searches on the internet I did come across some examples of using Regular Expressions to extract (more...)
Some time ago I had some blog posts introducing some of the basic Statistical function available in Oracle. Here are the links to these.
Over the past while I've been working a lot with text strings. Some of these have been short in length like tweets from Twitter, or longer pieces of text like product reviews. Plus others of various lengths.
In all these scenarios I have to break up the data into individual works or Tokens.
The examples given below illustrate how you can take a string and break it into its individual tokens. In addition to tokenising (more...)
An occasional question in the forums relates to issues ordering a particular column. It's one of those things that will probably keep coming up, so it's worth having another reference out here on the web.
The basic example stems from the need to order data that might contain characters.
with data as
(select '1' vc from dual union all
select '11' vc from dual union all
select '2' vc from dual union all
select 'a' (more...)
Occasionally I'll want some form of report noting file sizes of blobs in a database.
The solution is relatively simple, and I thought I'd write it up here for a place to copy syntax each time.
APEX users also have a handy table to verify this against (apex_application_files). Well, a synonym/view that ultimately maps to the core table wwv_flow_file_objects$.
It contains a doc_size
column, which is no doubt evaluated at some point during upload of (more...)
Part 1—DON’T PANIC: Even experienced application developers may not understand EXPLAIN PLAN output. As the great Renaissance artist Leonardo da Vinci said in his dicourse on painting: “Those who are in love with practice without science are like the sailor who gets into a ship without rudder or compass, who is never certain where he […]