Time to resurrect blogging!

Sorry for staying quiet for some time, but for some good reasons. Some of these reasons will be explained in later posts, but for now I would like to share the story I wrote upon request of Steven Feuerstein, who asked to tell how PL/SQL impacted our life. Here is my story:

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I started to work with databases already in college, but more from the data modelling/business analysis angle. When I moved to (more...)

★ Database as a Storage (DBaaS) vs. Thick Database

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:

The (more...)

Avoid UTL_FILE_DIR Security Weakness – Use Oracle Directories Instead

Integrigy:

The UTL_FILE database package is used to read from and write to operating system directories and files. By default, PUBLIC is granted execute permission on UTL_FILE. Therefore, any database account may read from and write to files in the directories specified in the UTL_FILE_DIR database initialization parameter [...] Security considerations with UTL_FILE can be mitigated by removing all directories from UTL_FILE_DIR and using the Directory functionality instead.


© Eddie Awad's Blog, (more...)

New in Oracle 12c: Querying an Associative Array in PL/SQL Programs

I was aware that up to Oracle 11g, a PL/SQL program wasn’t allowed use an associative array in a SQL statement. This is what happens when I try to do it.

SQL> drop table test_array purge;

Table dropped.

SQL> create table test_array as
  2  select level num_col from dual
  3  connect by level <= 10;

Table created.

SQL> select * from test_array;

   NUM_COL
----------
         1
         2
         3
         4
         5
         6
         7
         8
         9
        10                                                                      

10  (more...)

Are You Using BULK COLLECT and FORALL for Bulk Processing Yet?

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...)

The APEX_JSON package: Generating JSON from PL/SQL

In my previous blog post, I took a look at the new APEX_JSON package that ships with Apex 5.0 and its capabilities for parsing JSON.

In this blog post, I am going to look at how the APEX_JSON package can be used to generate JSON from data in your database using PL/SQL.

There are multiple ways of creating JSON output using the APEX_JSON package. There are several overloaded write() procedures which can output (more...)

Some things to share…

I have been awfully quiet on my blog lately. I think that is because I have been busy with other things, like my garden and stuff like that. There are some ‘techie’ thing I have done in the meantime, though,

Tech14-Ive_SubmittedI have submitted a couple of abstracts for Tech14. Hope at least one of them gets selected. I really like presenting and if it is in a different country, that is just a plus. That (more...)

PL/SQL oddity

sokrates@12.1 > create procedure p is begin null; end this_does_not_compile;
  2  /

Warning: Procedure created with compilation errors.

sokrates@12.1 > show errors
Errors for PROCEDURE P:

LINE/COL ERROR
-------- -----------------------------------------------------------------
1/32	 PLS-00113: END identifier 'THIS_DOES_NOT_COMPILE' must match 'P'
	 at line 1, column 11

sokrates@12.1 > REM expexted
sokrates@12.1 > create function f return number is begin return null; end this_does_not_compile;
  2  /

Warning: Function created with compilation errors.

sokrates@12.1 >  (more...)

PL/SQL vs SQL

plsql_logoThere is a ‘rule’, I think it was created by Tom Kyte, stating: If you can do it in SQL, do it in SQL. I came across some code the other day that makes perfect sense to do then you are running an Oracle 10g (or earlier) instance. I rewrote the code to use only the EMP and DEPT tables to protect the suspects and maybe innocent.

The function defined is something like this:

PL/SQL, UTL_HTTP and Digest Authentication

For the first time in what seems like ages, I've actually put together a piece of code worth sharing. It's not that I haven't been working, but just that it has all been very 'in-house' specific.

However I had a recent requirement to use a web service that makes use of Digest Authentication. If you have look at the UTL_HTTP SET_AUTHENTICATION subprogram, it only addresses Basic authentication (and, apparently, Amazon S3 which looks intriguing).

In (more...)

Readable Code for Modify_Snapshot_Settings

It annoyed me slightly that when I googled modify_snapshot_settings just now and all of the examples used huge numbers for the retention with (at best) a brief comment saying what the number meant. Here is a better example with slightly more readable code. Hope a few people down the road (more...)

Oracle 12c OFFSET…FETCH.. bug?

Working on the chapter that covers best ways of manipulating with object collection. Of course, if you talk about pagination of the rowset, it is very tempting to test Oracle 12c new feature - OFFSET…FETCH.

Unfortunately, immediately got an issue. It seems to me that passing a variable to FETCH (more...)

Dynamic SQL and RESULT_CACHE

Over the weekend one of my friends asked me for a clarification on RESULT_CACHE - a really interesting functionality that allows Oracle to cache in SGA results of PL/SQL function calls.

The point of confusion was the fact that between 11gR1 and 11gR2 Oracle development team significantly re-thought this feature (more...)

Performance tuning. Spending time is NOT OK (if you do not know exactly why)

Yet another performance tuning story, similar to one that happened about a month ago. Just to keep it short:

  • once upon a time there was a very time-consuming module.
  • eventually we were forced to take much closer look - WHY is it so time-consuming
  • we found in our own (more...)

Oracle Internals. Digging out PL/SQL fine-grain dependencies

After a couple of requests at IOUG Collab'13 I decided to resurrect a pretty old topic that I've participated in 2008 (since in 5 years there was no changes on that front :-) ).

As we all know, starting version 11g Oracle tracks PL/SQL dependencies in much more granular way (more...)

Oracle Dynamic SQL: generic search – crazy case

For the Friday evening I decided to dig out my example from the most recent of my published books (Expert PL/SQL Practices, APress, 2011) - it was a very fun project to work with: first, to come with with the idea of such multi-author book, second, to write a chapter focused on Dynamic SQL.

As one of the examples I decided to illustrate how XMLType can be used as both a collection of (more...)

Oracle Dynamic SQL: generic search – REF CURSOR

This post is a continuation of a topic, I've raised previously - dynamic implementation of generic searches. As  I mentioned in that post, there are circumstances, when it is much more convenient to return a pointer to a row-set instead of that row-set. Or in terms of Oracle - REF CURSOR (more...)

Oracle Dynamic SQL: generic search – simple case

It is a very common problem - how do you implement generic search over the table? By generic search I mean that users are provided with tons of different options that could be used in all possible permutations.

It leads to a standard problem - how do you make sure (more...)

Fun with CHAR

I'm busy deriving file layouts from PL/SQL. Probably close to 100 file definitions...each of them slightly different, each of them defined in the code. Fun!

There are a mixture of types too, fixed width, csv, etc. Thankfully, I've read enough of the code now that it's relatively easy to (more...)

dbms_output.put_line

I've been scratching my eyes out lately trying to reverse engineer some lots of PL/SQL.

One thing I've seen a lot of is calls to dbms_output.put_line. Fortunately, I've seen some dbms_application_info.set_module and other system calls too. But back to that first one.

1. When I used dbms_output, (more...)