Dear admin please help serious osc error

I just know powweb.com opgrade the sql server
Cause my osc can not run
the error message below

Warning: session_start(): open(/tmp/sess_22de7f674b2722e7f3633702ae0512b1, O_RDWR) failed: Permission denied (13) in /www/g/gomail/htdocs/catalog/includes/functions/sessions.php on line 67

Dear Admin
please help

[stevel]

I would have expected to see this error weeks ago. In the two configure.php files, find the line near the bottom that reads:

PHP Code:

define('STORE_SESSIONS',''); 


and change it to

PHP Code:

define('STORE_SESSIONS','mysql'); 


BTW, if you do set the storage to mysql be sure to go back and add a multi-column index on the sesskey and expiry columns. This will use slightly more room on the disk but will greatly improve performance...especially if you have more than a few sessions in the table.

Bobby

[stevel]

Care to elaborate, Bobby? Or point to a discussion elsewhere?

The default installation has the sesskey as primary but this alone is not enough. Most of the session related queries also have a expiry check (as a simple garbage collection system). This will cause an entire table scan on each page request.

Let's say the store is somewhat active and gets 500 unique hits per hour. Further, let's say that the store admin has it configured to recreate sessions and also the other checks such as IP verification, user agent, etc. The sessions table could potentially get rather large and range from 12,000 to 6,000 rows depending on store configuration and also customer browser settings.

Hence, those entire table scans slow down the performance of the entire store even though they appear to be simple and fast executing. The problem is with that expiry!

I have tested this thoroughly on stores that range from $100 daily revenue to $10K daily revenue...the results are proven and the technique is simple.

Go into phpMyAdmin and select the sessions table. Next, add a multi-column index by using the "Create an index on ___ columns" option. The next screen will allow you to select which columns will be used. Don't worry about giving it a name...it'll use the columns as default when naming. The index type should be "INDEX".

Make sure the two columns chosen are first sesskey then next expiry. This is critical as MySQL uses left most prefixing when choosing which index to use!!

After creating the new multi-olumn index you may need to analyze the table. Either select this action from the menu available in phpMyAdmin or run this query:

PHP Code:

ANALYZE TABLE `sessions`; 


This will force MySQL to analyze the table and use the new index.

Does 1 set of queries determine overall page performance? No. However, if one were versed in all the optimization techniques from application_top.php to application_bottom.php the page parse time and MySQL time can be reduced by roughly 90%

Bobby

[stevel]

Thanks - I'll have to try that.