Tech Blog

I found that using php function, strip_tags, does not remove all the markup elements correctly from the subject content.  First of all, if an anchor link includes a line break, it will not be removed correctly.  Also, the style information is not properly removed as well.  In the following script, I also added in the regex to remove any content in between script tags, but that may or may not be necessary.

function strip_all_tags($content)
{
$content = preg_replace(’/\n/’,’ ‘,$content);
$content = preg_replace(’/<script.*<\/script>/U’,’ ‘,$content);
$content = preg_replace(’/<style.*<\/style>/U’,’ ‘,$content);
$content = strip_tags(strtolower($content));
return $content;
}

The function will remove all line breaks so strip_tags will not have problems with finding all markups.  Since strip_tags does not remove <style> tags, the new function will remove them using regex.

Tags: Coding, Open Source by frank
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Here is the continuation of the experiment done previously on Mysql on Windows vs Linux. After doing more analysis and observation, it appeared that the difference in speed for the benchmark tests were not related to Windows and Linux but were related to the processor. The previous test just happened to have AMD 64s on the Linux machines and Intel Xeon 32bits on Windows. We hypothesized that the increased throughput of the 64bit processors resulted in about half the time required to return the same query run on a 32bit machine.

View the previous results

So we decided to test the same query again on a Windows machine with an AMD 64 X2. This time the result for the query took 7.35 second, almost the same as the other AMD 64s running Linux.

One more test to run the query on a Windows Intel 64bit chip machine would better solidify our hypothesis.

Tags: Open Source, admin, benchmark, hardware, linux, mysql by frank
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I have a spider crawling the web written in PHP running constantly to insert and update data in a Mysql database.  Today, it kept stopping on a records with the error message, “Mysql server has gone away”.  It certainly did not time out as just starting the process again would result in this message immediately.  The script did not close out the connection to the DB as it had worked just fine for over a year.

Finally, I found that the problem was max_allowed_packet setting in my.cnf was too small.  It was set to 2MB and when Mysql receives a query larger than that, it assumes that something must have gone wrong and closes the connection.  I increased that parameter to 4MB and everything is working fine now.

Tags: Open Source, admin, mysql by frank
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I was working on optimizing a Mysql database today and accidentally stumbled upon a benchmarking exercise. The original Mysql database is hosted on a Windows Server 2003. I develop on a Mysql database server running on Ubuntu Linux. The Linux server ran the same query twice as fast as the Windows server without using caching or anything. I know that Linux does I/O caching on its own as well so I even tried running the query after a fresh reboot to rule out that factor. Then I got help from a colleague and started tweaking with the my.cnf/my.ini to make sure they were the same and each time, the results came back about the same. Mysql on Windows was consistently slower than Mysql on Linux.

Then we decided to load the database onto other servers for more data points on this Mysql performance test. We ran the same query returning 429 rows of data with 13 table joins and a couple of sub-queries. All queries were run on the command line client on the servers themselves to avoid network lag.  All servers are running Mysql 5.0.x.

Results

1. Ubuntu Linux: 0.70 seconds
2. CentOS: 0.78 seconds
3. Windows 2003 Server: 1.40 seconds
4. Windows 2003 Server: 1.42 seconds

Server hardware

1. Ubuntu Linux
AMD ATHLON 64 X2 4200+
2GB DDR400
200GB 7200RPM SATA/150

2. CentOS
Dual Opteron 240
2GB DDR ECC
120GB 7200RPM SATA/300

3. Windows 2003 Server
Dual Xeon
2GB DDR ECC
7200RPM PATA

4. Windows 2003 Server
2 Dual Xeon (4 CPUs)
8GB DDR ECC
3 73GB 10,000RPM SCSI in RAID 5

Tags: Open Source, System, benchmark, hardware, linux, mysql, server by frank
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I have been trying to benchmark the sql calls to mysql from an application without success. Even when I set the SELECT statement to SQL_NO_CACHE, the results seemed to be still cached. Apparently, Linux does its own caching of disk reads also. That was giving me incorrect benchmark results if I hit the same data twice.

For those using Linux kernel 2.6.16 or higher, you can clear Linux cache with the following command.
echo 3 > /proc/sys/vm/drop_caches

Unfortunately for me, I am stuck on 2.5.xx and will have to figure out another method.

Tags: Open Source, admin, linux, mysql by frank
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If you still think open source applications are just the wild west without any sort of structured support, think again. The Drupal Conference happening in Boston is an example of how organized open source has become. No longer are conventions just for Microsoft, IBM, Oracle, etc.

Tags: Open Source by frank
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The error comes up when trying to use file based session storage instead of database. Apparently, the configuration for what directory to store the session is not in the configuration files but in the database table “configuration”.

If you upgrade your php to version 5.2.1, the database session storage breaks. Therefore, I had to switch to file system based storage. But the catch was that I no longer could log into admin as the session could not start. The configuration.php files did not have this constant.

The way to fix this is to log into your database and update the session directory record.

“UPDATE configuration SET configuration_value=’/your/new/direcotory/’ WHERE configuration_title=’session directory’;”

System Specs:
php.5.2.1
zencart 1.3.5
apache 1.3.37
MySQL 5.0.45

Tags: E-commerce, Open Source, admin by frank
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Just encountered a problem that was painful to deal with while configuring SSL on apache for linux.  The httpd.conf had a tag, , before all the SSL configuration lines.  In order for any commands within and to be loaded on service start, you must use the -D attribute like this.

$ service httpd -D SSL -k start

Also, I found that restart does not always take new changes to my conf files.

$ service httpd -D SSL -k restart

Instead, use the stop then the start command to be sure.

$service httpd -D SSL -k stop
$service httpd -D SSL -k start

That was a source of much pain while working on this particular server.

Tags: Open Source, admin, apache, server, ssl by frank
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Configuration:

Linux
Apache 1.3
Mysql 5
PHP 5
Zencart 1.3.5
Chemo Ultimate URL for Zencart 1.3.5

Problem:

After installation, the error message
1054 Unknown column ‘c.parent_id’ in ‘on clause’
shows up on any page in the catalog.

Fix:

Make the following change to /include/classes/seo.url.php
Original:

SELECT c.categories_id as id, c.parent_id, cd.categories_name as cName, cd2.categories_name as pName
FROM “.TABLE_CATEGORIES.” c,
“.TABLE_CATEGORIES_DESCRIPTION.” cd
LEFT JOIN “.TABLE_CATEGORIES_DESCRIPTION.” cd2
ON c.parent_id=cd2.categories_id AND cd2.language_id=’”.(int)$this->languages_id.”‘
WHERE c.categories_id=cd.categories_id
AND cd.language_id=’”.(int)$this->languages_id.”‘”;

Change:

“SELECT c.categories_id as id, c.parent_id, cd.categories_name as cName, cd2.categories_name as pName
FROM
“.TABLE_CATEGORIES_DESCRIPTION.” cd,
“.TABLE_CATEGORIES.” c
LEFT JOIN “.TABLE_CATEGORIES_DESCRIPTION.” cd2
ON c.parent_id=cd2.categories_id AND cd2.language_id=’”.(int)$this->languages_id.”‘
WHERE c.categories_id=cd.categories_id
AND cd.language_id=’”.(int)$this->languages_id.”‘”;

Tags: Coding, E-commerce, Open Source, Software by frank
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This post is to help those who are using Zen Cart and are using new product types with Ultimate SEO URL package installed. There are a couple of things to change in order to make everything work together as it took me a couple of hours to figure out. I hope this will help others save these couple of hours of hair pulling.

Prerequisite:

Zen Cart installed
New product type added
Ultimate SEO URL package installed
Goal:

Have the URLs for the products using the new product type show URLs in this format.

http://www.domain.com/[product name]-p-[product id].html

Changes Required:

NOTE: [handler_name] is the new product type name added.

1. File - seo.url.php
   Original:
   $seo_pages = array(
   FILENAME_DEFAULT,
   FILENAME_PRODUCT_INFO,
   FILENAME_POPUP_IMAGE,
   FILENAME_PRODUCT_REVIEWS,
   FILENAME_PRODUCT_REVIEWS_INFO,
   );Result:
   $seo_pages = array(
   FILENAME_DEFAULT,
   FILENAME_PRODUCT_INFO,
   FILENAME_POPUP_IMAGE,
   FILENAME_PRODUCT_REVIEWS,
   FILENAME_PRODUCT_REVIEWS_INFO,
   FILENAME_[handler name]_INFO
   );
2. File - seo.url.php
   Original:
   $this->reg_anchors = array(
   ‘products_id’ => ‘-p-’,
   ‘cPath’ => ‘-c-’,
   ‘manufacturers_id’ => ‘-m-’,
   ‘pID’ => ‘-pi-’,
   ‘products_id_review’ => ‘-pr-’,
   ‘products_id_review_info’ => ‘-pri-’,Result:
   $this->reg_anchors = array(
   ‘products_id’ => ‘-p-’,
   ‘cPath’ => ‘-c-’,
   ‘manufacturers_id’ => ‘-m-’,
   ‘pID’ => ‘-pi-’,
   ‘products_id_review’ => ‘-pr-’,
   ‘products_id_review_info’ => ‘-pri-’,
   ‘[handler name]_id’ => ‘-pji-’,
   
3. File - seo.url.php -> function parse_parameters
   Find “case ‘products_id’:”
   Within this case statement, add the following.case ($page == FILENAME_[handler name]_INFO):
   $url = $this->make_url($page, $this->get_product_name($p2[1]), ‘[handler_name]_id’, $p2[1], ‘.html’, $separator);
   break;
4. File - [webroot]/includes/filenames.php
   Add the following definition.define(’FILENAME_[handler name]_INFO’, ‘[handler name]_info’);
5. File - [webroot]/.htaccess
   Add the following rewrite rule.RewriteRule ^(.*)-pji-(.*).html$ index\.php?main_page=[ handler_name]_info&products_id=$2&%{QUERY_STRING} [L]

Tags: Coding, E-commerce, Open Source by frank
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