MacLochlainns Weblog

Working on my stuff today, and the Belkin Flip DVI KVM Switch (product discontinued as of 2012) went nuts. First, I lost the keyboard, and then video. After a couple fruitless minutes, I did the unthinkable and opted for the 7 second to oblivion restart while two VMWare instances were up and running. By the way, I disconnected the Belkin Flip DVI KVM Switch because that was the last straw. For those looking at the product, I’d advise against it because infrequently the device transmits haze or golden flashing pixels. Also, this wasn’t the first time the keyboard disconnected itself without rhyme or reason.

All my VMs were locked when I rebooted. It didn’t matter whether they were running or not when I did the forced shutdown. This is not the image you want to see when you’re short on time against a fixed deadline.

The fix was simple. You go to the directory where each VM is located and find if you have locked files. You can run this command to find them:

$ ls *.lck

If they’re locked you’ll see something this:

564df021-1de5-dec0-942a-37635b35361b.vmem.lck:
M00680.lck
 
Windows XP Professional 32-bit.vmdk.lck:
M25400.lck
 
Windows XP Professional 32-bit.vmx.lck:
M47433.lck

You need to delete all three files, I used this command:

$ rm -rf *.lck

When you restart VMWare Fusion, everything will be fine. Hope this helps a few folks.

I put up a contact page (@Contact Me) for two reasons. Too many folks wanted to ask something and could only do so through a comment. I would review the comment, email them, et cetera. Reason two is simpler, I should have done it from the outset.

There were a few gotchas beyond installing and securing your public and private keys. I figured that it might be helpful to note them here, especially if I have to troubleshoot it later. 😉

1. You need create a template, like contact.php script, which should include your contact form. You’ll also embed some reCAPTCHA PHP inside this file.

<?php
<form action="/wp-content/themes/<theme name>/contact_code.php" class="contact" method="post">
?>

<?php
  // Include the reCAPTCHA library, this assumes a relative directory.
  require_once('recaptchalib.php');
 
  // Get a key from http://recaptcha.net/api/getkey
  $publickey = "<your public key value goes here>";
 
  // The response from reCAPTCHA
  $resp = null;
  // The error code from reCAPTCHA, if any
  $error = null;
 
  echo recaptcha_get_html($publickey, $error);
?>

2. You need to put the following WordPress template stub at the beginning of your contact.php page.

<?php
  /*
    Template Name: contact
  */
?>

3. After you create and position the contact.php file in the /wp-content/themes/<theme_name>/ within the document root, you should create a new blog page. You don’t put any text in the page, rather you simply choose the contact.php from your list of templates. You also need a title for the page, I used @contact-me (the @ won’t be used in any reference in the URL), which is an alias to the page

4. You need to put the balance of your PHP code in a separate file, like contact_code.php and put the URL re-write and reCAPTCHA calls here.

<?php
  // Include the library for reCAPTCHA at the theme level in the file hierarchy.
  require_once('recaptchalib.php');
 
  // Put any form PHP here.
 
  // Declare your private key.
  $privatekey = "<put your private key here>";
 
  // Check whether there a reCAPTCHA response?
  if ($_POST["recaptcha_response_field"]) {
    $resp = recaptcha_check_answer($privatekey
                                  ,$_SERVER["REMOTE_ADDR"]
                                  ,$_POST["recaptcha_challenge_field"]
                                  ,$_POST["recaptcha_response_field"]);
    // Check for valid response.
    if ($resp->is_valid) {
      if(!$errors) {
        $to = '<email here>@<domain here>';
        $subject = $subject;
        $message = "From: ".$name."\nMessage: ".$message;
        $from = 'From:'.$email;
        mail($to,$subject,$message,$from);
 
        // Set the header to the document root when successful.
        header("Location: /");
      }
    }
    else {
      // Set the header to the virtual path for the contact page.
      header("Location: /contact-me/");
      $error = $resp->error;
    }
  }
?>

That’s about it. If I forgot something, you’ll let me know.

Somebody asked me to post some examples of Large Object syntax. I checked Chapter 9 of the Oracle Database SecureFiles and Large Object Developer’s Guide, and I agree an example or two would be helpful. I’ve provided CREATE and ALTER statements.

Here’s a sample CREATE TABLE statement for a CLOB, BLOB, and BFILE:

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CREATE TABLE item
( item_id             NUMBER        CONSTRAINT pk_item    PRIMARY KEY
, item_barcode        VARCHAR2(20)  CONSTRAINT nn_item_1  NOT NULL
, item_type           NUMBER        CONSTRAINT nn_item_2  NOT NULL
, item_title          VARCHAR2(60)  CONSTRAINT nn_item_3  NOT NULL
, item_subtitle       VARCHAR2(60) 
, item_desc           CLOB          CONSTRAINT nn_item_4  NOT NULL
, item_blob           BLOB
, item_photo          BFILE
, item_rating         VARCHAR2(8)   CONSTRAINT nn_item_5  NOT NULL
, item_rating_agency  VARCHAR2(4)   CONSTRAINT nn_item_6  NOT NULL
, item_release_date   DATE          CONSTRAINT nn_item_7  NOT NULL
, created_by          NUMBER        CONSTRAINT nn_item_8  NOT NULL
, creation_date       DATE          CONSTRAINT nn_item_9  NOT NULL
, last_updated_by     NUMBER        CONSTRAINT nn_item_10 NOT NULL
, last_update_date    DATE          CONSTRAINT nn_item_11 NOT NULL
, CONSTRAINT fk_item_1                      FOREIGN KEY(item_type)
  REFERENCES common_lookup(common_lookup_id)
, CONSTRAINT fk_item_2                      FOREIGN KEY(created_by)
  REFERENCES system_user(system_user_id)
, CONSTRAINT fk_item_3                      FOREIGN KEY(last_updated_by)
  REFERENCES system_user(system_user_id))
  LOB (item_desc) STORE AS BASICFILE item_desc
  (TABLESPACE users ENABLE STORAGE IN ROW CHUNK 32768
   PCTVERSION 10 NOCACHE LOGGING
   STORAGE (INITIAL 1048576
            NEXT 1048576
            MINEXTENTS 1
            MAXEXTENTS 2147483645))  
, LOB (item_blob) STORE AS item_blob
  (TABLESPACE users ENABLE STORAGE IN ROW CHUNK 32768
   PCTVERSION 10 NOCACHE LOGGING
   STORAGE (INITIAL 1048576
            NEXT 1048576
            MINEXTENTS 1
            MAXEXTENTS 2147483645));

If you attempt to make the CHUNK size greater than 32,768, it will raise an ORA-22851: invalid CHUNK LOB storage option value error.

Here’s a sample ALTER TABLE statement that adds a new large object column to a table. You can’t modify an existing large object column. You raise an ORA-22859: invalid modification of columns error when you try it. If you need to make modifications, check this post form last year on re-organizing LOB indexes.

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ALTER TABLE item ADD (another CLOB)
LOB (another) STORE AS BASICFILE item_clob
(TABLESPACE users ENABLE STORAGE IN ROW CHUNK 32768
 PCTVERSION 10 NOCACHE LOGGING
 STORAGE (INITIAL 1048576
          NEXT 1048576
          MINEXTENTS 1
          MAXEXTENTS 2147483645));

This all makes sense, but hold on there’s a potential problem when you add a large object column to a table. I’m not sure it’s a bug but I’ll probably open a TAR on it later in the week (arghhhh! I once worked in Oracle Support. :-)). Anyway, here’s what I found:

If you drop and recreate the table, you can encounter an ORA-01430 error. It appears that the large object is really hanging out in the catalog. As soon as you try to re-add it, you get the error.

If you describe the table after recreating it, you’ll see the following:

SQL> DESCRIBE item
 Name                                      Null?    Type
 ----------------------------------------- -------- ---------------
 ITEM_ID                                   NOT NULL NUMBER
 ITEM_BARCODE                              NOT NULL VARCHAR2(20)
 ITEM_TYPE                                 NOT NULL NUMBER
 ITEM_TITLE                                NOT NULL VARCHAR2(60)
 ITEM_SUBTITLE                                      VARCHAR2(60)
 ITEM_DESC                                 NOT NULL CLOB
 ITEM_BLOB                                          BLOB
 ITEM_PHOTO                                         BINARY FILE LOB
 ITEM_RATING                               NOT NULL VARCHAR2(8)
 ITEM_RATING_AGENCY                        NOT NULL VARCHAR2(4)
 ITEM_RELEASE_DATE                         NOT NULL DATE
 CREATED_BY                                NOT NULL NUMBER
 CREATION_DATE                             NOT NULL DATE
 LAST_UPDATED_BY                           NOT NULL NUMBER
 LAST_UPDATE_DATE                          NOT NULL DATE

Also, if you run the following query with the DBMS_METADATA package, the column doesn’t exist in the table defintion:

SELECT dbms_metadata.get_ddl('TABLE','ITEM') FROM dual;

If try to run the ALTER statement to add the column that doesn’t appear to exist, you’ll get the following message in Oracle 11.1.0.7.0:

ALTER TABLE item ADD (another CLOB)
                      *
ERROR at line 1:
ORA-01430: COLUMN being added already EXISTS IN TABLE

If you rerun the DBMS_METADATA.GET_DDL query, it’ll be there in the table definition. Also, in its non-existence but existent state (ghost-state), there’s nothing in the DBA_LOB, or DBA_SEGMENT views. You can find a query to check large object segments and indexes here. My questions is where has it gone, why is it there, and did I do something wrong because this looks like basic functionality.

If you know the mystery or the existence of a bug, please post a comment.

It’s the end of our Spring term, and yes occasionally somebody can’t sign on to their Oracle instance because their event log is full. They get the following message on Winodws:

C:\>sqlplus / AS sysdba
 
SQL*Plus: Release 11.1.0.7.0 - Production ON Wed Jul 15 10:19:37 2009
 
Copyright (c) 1982, 2008, Oracle.  ALL rights reserved.
 
Enter password:
ERROR:
ORA-28056: Writing audit records TO Windows Event Log failed

The fix is simple, just delete your items from your Windows’ event log. 😉

I was playing around with some external table filtering examples, and I stumbled on a restriction that I’d previously missed. You can’t filter external data with SQL functions, like REGEXP_LIKE. Unfortunately, the limitation applies to equality and non-equality validation in combination with the AND and OR operators.

CREATE TABLE item_load
( item_title    VARCHAR2(60)
, item_subtitle VARCHAR2(60)
, release_date  DATE)
  ORGANIZATION EXTERNAL
  ( TYPE oracle_loader
    DEFAULT DIRECTORY upload_source
    ACCESS PARAMETERS
    ( RECORDS DELIMITED BY NEWLINE CHARACTERSET US7ASCII
      BADFILE     'UPLOAD_LOG':'item_load.bad'
      DISCARDFILE 'UPLOAD_LOG':'item_load.dis'
      LOGFILE     'UPLOAD_LOG':'item_load.log'
      LOAD WHEN (REGEXP_LIKE(item_title,'^Harry.'))
      FIELDS TERMINATED BY ','
      OPTIONALLY ENCLOSED BY "'"
      MISSING FIELD VALUES ARE NULL )
      LOCATION ('item_load.csv'))
REJECT LIMIT UNLIMITED;

It threw the following exception, which includes a new error message (at least for me), the KUP-01005. I suppose that basically means you can’t use function calls inside external table access parameters but I couldn’t find it in the documentation. Chapter 13 (the lucky number) in the Oracle Database Utilities 11g manual only provides examples of equality and non-equality.

Here’s the raise exception for those using external tables:

SQL> SELECT * FROM item_load;
SELECT * FROM item_load
              *
ERROR at line 1:
ORA-29913: error IN executing ODCIEXTTABLEOPEN callout
ORA-29400: DATA cartridge error
KUP-00554: error encountered while parsing access parameters
KUP-01005: syntax error: found "(": expecting one OF: "equal, notequal"
KUP-01007: at line 5 COLUMN 29

I couldn’t leave it alone, I tried the LIKE operator and a jackpot – another new error message:

KUP-01008: the bad identifier was: LIKE

It makes sense, it’s the 13th of July and two days before the new Harry Potter flick, therefore it must be Chapter 13 was calling to me. Hope this helps a few folks.

The fact that you could raise an ugly error when you query an external table always bothered me. I looked at Java stored procedures as the best solution initially. That was overkill. This afternoon, while writing about them for the new PL/SQL Workboook, it became clear. The fix is really easy.

If you know little to nothing about external tables, you can go read this earlier post. Likewise, if you don’t know about objects and object collection, you can refer to this post. Having provided you with the context, here’s an example that eliminates errors when querying an external table without an external file.

1. Create an external file, like this character table.

CREATE TABLE CHARACTER
( character_id NUMBER
, first_name VARCHAR2(20)
, last_name VARCHAR2(20))
  ORGANIZATION EXTERNAL
  ( TYPE oracle_loader
    DEFAULT DIRECTORY download
    ACCESS PARAMETERS
    ( RECORDS DELIMITED BY NEWLINE CHARACTERSET US7ASCII
      BADFILE     'DOWNLOAD':'character.bad'
      DISCARDFILE 'DOWNLOAD':'character.dis'
      LOGFILE     'DOWNLOAD':'character.log'
      FIELDS TERMINATED BY ','
      OPTIONALLY ENCLOSED BY "'"
      MISSING FIELD VALUES ARE NULL )
    LOCATION ('character.csv'))
REJECT LIMIT UNLIMITED;

2. Create a user-defined object type that mirrors your external table defintion, like this:

CREATE OR REPLACE TYPE character_obj IS OBJECT
( character_id NUMBER
, first_name VARCHAR2(20)
, last_name VARCHAR2(20));
/

3. Create a user-defined collection of your object type, like

CREATE OR REPLACE TYPE character_obj_table IS TABLE OF character_obj;
/

4. Create a function that returns the user-defined collection of your object type, like

CREATE OR REPLACE FUNCTION character_source
RETURN character_obj_table IS
  c          NUMBER;
  collection CHARACTER_OBJ_TABLE := character_obj_table();
BEGIN
  FOR i IN (SELECT * FROM CHARACTER) LOOP
    collection.EXTEND;
    collection(c) := character_obj( i.character_id
                                  , i.first_name
                                  , i.last_name);
    c := c + 1;
  END LOOP;
  RETURN collection;
EXCEPTION
  WHEN OTHERS THEN
    RETURN collection;
END;
/

5. Query the function not the table, which returns no rows found when the file doesn’t physically exist, or the file contains no data. Lastly, the function returns the data when it is there.

SELECT * FROM TABLE(character_source);

Hope this helps those using external tables to avoid the typical error stack:

SELECT * FROM CHARACTER
*
ERROR at line 1:
ORA-29913: error IN executing ODCIEXTTABLEOPEN callout
ORA-29400: DATA cartridge error
KUP-04040: file CHARACTER.csv IN CHARACTER NOT found

I also wrote this older post about confirming it in the database catalog. If you any follow-up suggestions, please let me know.

While SQL Developer is a nice tool and free, Toad is still an awesome development platform, albeit for Windows. In fact, it was annoying to have to install the Microsoft .NET Framework before installing it. It is free for MySQL!

Since my students have to do all their work in Oracle and then port it to MySQL, I demonstrate Quest’s Toad for MySQL’s at the end of the term. I don’t want them to leverage the automatic ERD diagramming while they’re learning how to do it.

There’s only one real trick to making automatic ERD diagramming work. That trick requires that you write your loading scripts for the Inno DB and use referential integrity constraints. My sample Video Store scripts for my database class are updated for MySQL referential integrity.

Unlike the friendly CASCADE CONSTRAINTS clause you can use in Oracle, MySQL won’t let you create a re-runnable script with only DDL statements. Actually, the constraint comes from the InnoDB engine. You must issue a specialized InnoDB command before running your script:

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-- This enables dropping tables with foreign key dependencies.
-- It is specific to the InnoDB Engine.
SET FOREIGN_KEY_CHECKS = 0;

Primary keys are a bit different from Oracle and it appears you can’t name them, at least I couldn’t see how to do it. Here’s an example of primary and foreign key constraints in MySQL. The primary key is inline and the foreign key constraints are out of line. This example from the downloadable scripts uses self referencing foreign key constraints.

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CREATE TABLE system_user
( system_user_id              INT UNSIGNED PRIMARY KEY AUTO_INCREMENT
, system_user_name            CHAR(20)     NOT NULL
, system_user_group_id        INT UNSIGNED NOT NULL
, system_user_type            INT UNSIGNED NOT NULL
, first_name                  CHAR(20)
, middle_name                 CHAR(20)
, last_name                   CHAR(20)
, created_by                  INT UNSIGNED NOT NULL
, creation_date               DATE         NOT NULL
, last_updated_by             INT UNSIGNED NOT NULL
, last_update_date            DATE         NOT NULL
, KEY system_user_fk1 (created_by)
, CONSTRAINT system_user_fk1 FOREIGN KEY (created_by)
  REFERENCES system_user (system_user_id)
, KEY system_user_fk2 (last_updated_by)
, CONSTRAINT system_user_fk2 FOREIGN KEY (last_updated_by)
  REFERENCES system_user (system_user_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Once installed (instructions are here) and connected to the MySQL database, you simply click the ERD icon in the top panel and drag the tables onto the canvas. You’ll see something like this (by the way click on the image to see its full size):

Have fun with it. It’ll be interesting to see how Oracle positions MySQL when they own it. My hunch is that they’ll continue to sell it and provide it as an open source product.

Sometimes you chalk something up as straightforward because you’ve done it a while. I did that in a lab assignment recently. It asked my students to upload a large text file and image to the MySQL database, store them in a TEXT and MEDIUMBLOB column, and read them back out of the database, like this:

The trick was that I wanted them to read the file into a string and then load the string. There wasn’t a single code example to do this out there, except some that might exist behind an account and credit card payment. I put together a complete example like the Oracle LOB processing page. You can find it here in the MySQL LOB processing blog page. More or less, it shows you how to stream an image into a MySQL database in chunks (I chose 8 K chunks).

The general tricks to upload a string require you enclose to enclose them with the addslashes() function before assigning a binary stream to a variable, then stripslashes() function by segment before you load it to the database. You really don’t need to do that. It’s a myth. The binary stream doesn’t require that extra handling. In fact, you can corrupt certain images when you use the addslashes() and stripslashes() functions; they should be avoided in this context.

You should do it in streams (at least when they’re larger than 1 MB), I chose the procedural mysqli to demonstrate it because there wasn’t an example that I or my students could find on the web. Just for information, some laptops don’t have the resources to accommodate LARGEBLOB datatypes on the Windows OS. The BLOB or MEDIUMBLOB should work fine, especially for this little example.

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    // Declare a PL/SQL execution command.
    $sql = "UPDATE item SET item_blob = ? WHERE item_id =  ?";
 
    // Prepare statement and link it to a connection.
    if (mysqli_stmt_prepare($stmt,$sql)) {
      mysqli_stmt_bind_param($stmt,"bi",$item_blob,$id);
 
      $start = 0;
      $chunk = 8192;
      while ($start < strlen($item_blob)) {
        mysqli_send_long_data($stmt,0,substr($item_blob,$start,$chunk));
        $start += $chunk;
      }

You can find the code in that blog page referenced. Hope it helps some folks.

I just wanted to see how Zend Server Community Edition might be broken. Performing a full feature install on Windows x64, I confirmed that Zend Server’s Java Bridge depends on the 32-bit JRE (common sense prevails). Installing it against the JRE 64-bit jvm.dll did raised an exception but none of the instructions address the problem.

It’s one of those simplifying assumptions – everybody knows 32-bit software works with 32-bit software. Anybody running on Windows XP x64 should know that they may need a JDK 64-bit and both a JRE 64-bit and JRE 32-bit for some applications. For those who don’t know this, like my students and other newbies, when you run Windows XP the 64-bit stuff goes in the C:\Program Files directory and the 32-bit stuff goes in the C:\Program Files (x86) directory. This lets you develop 32-bit or 64-bit Java applications on the same 64-bit machine.

Another tidbit of interest, don’t choose a full install if you’ve already installed MySQL. The Zend Community Server isn’t smart enough to alter the configuration to another port, and their my.ini points to a 3306 listener port. This causes the MySQL_ZendServer51 service to fail. It also doesn’t uninstall well. If you don’t want to clean the Windows Registry, don’t choose to install a second MySQL.

As an FYI, the Zend installation of MySQL doesn’t put a password on the root account. Don’t forget to add one after the install if you go down the full product road. This has the Zend Server Community Edition installation instructions.

I saw a post in the OTN forum that asked a simple question and had no simple example as an answer, so I thought it would be nice to provide one. Basically, somebody wanted to know how to call into a stored procedure and return a value with more or less one pass-by-value and another pass-by-reference variable.

This defines a simple echo procedure, which takes a message and returns a formatted message:

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CREATE OR REPLACE PROCEDURE echo
( message IN     VARCHAR2
, reply      OUT VARCHAR2 ) IS
BEGIN
  reply := 'Message ['||message||'] received.';
END;
/

The following PHP calls the procedure and returns the value. It uses the required connection syntax for the Zend Server Community Edition.

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<?php
  // Attempt to connect to your database.
  $c = @oci_connect("student", "student", "localhost/xe");
  if (!$c) {
    print "Sorry! The connection to the database failed. Please try again later.";
    die();
  }
  else {
    // Initialize incoming message whether or not parameter sent.
    $msg_in = (isset($_GET['msg'])) ? $_GET['msg'] : "Cat got your keyboard?";
 
    // Set the call statement, like a SQL statement.
    $sql = "BEGIN echo(:a,:b); END;";
 
    // Prepare the statement and bind the two strings.
    $stmt = oci_parse($c,$sql);
 
    // Bind local variables into PHP statement, you need to size OUT only variables.
    oci_bind_by_name($stmt, ":a", $msg_in);
    oci_bind_by_name($stmt, ":b", $msg_out, 80, SQLT_CHR);
 
    // Execute it and print success or failure message.
    if (oci_execute($stmt)) {
      print $msg_out;
    }
    else {
      print "Sorry, I can't do that Dave...";
    }
    // Free resources.
    oci_free_statement($stmt);
    oci_close($c);
  }
?>

You can then test it with or without a parameter, like this example with a parameter:

http://localhost/message_reply.php?msg="Sample message"

I put a link in the forum to this, and I hope it helps a few folks.