Magento – catalog_product_flat is not taking new attributes

If you look in Mage/Catalog/etc/config.xml you will find this line:

<add_filterable_attributes>0</add_filterable_attributes>

This means that the filterable attributes are not added to the flat tables by default.
If you change that value to 1, you should see the filterable attributes in the flat tables.

You can change it for test purposes directly in the core file, but don't leave it like that if you decide that you need it.

In order to change it the proper way, build your own module that does it.
You will need 2 files for that.

app/etc/modules/[Namespace]_[Module].xml - the declaration file

<?xml version="1.0"?>
<config>
    <modules>
        <[Namespace]_[Module]>
            <codePool>local</codePool>
            <active>true</active>
            <depends>
                <Mage_Catalog /> <!-- must depend on the catalog module so its config is loaded after the config of the catalog -->
            </depends>
        </[Namespace]_[Module]>
    </modules>
</config>

app/code/local/[Namespace]/[Module]/etc/config.xml - the configuration file where youo override the config setting

<?xml version="1.0"?>
<config>
    <modules>
        <[Namespace]_[Module]>
            <version>1.0.0</version>
        </[Namespace]_[Module]>
    </modules>
    <global>
        <catalog>
            <product>
                <flat>
                    <add_filterable_attributes>1</add_filterable_attributes> <!-- this should override the default setting -->
                </flat>
            </product>
        </catalog>
    </global>
</config>

Clear the cache and reindex. You should see the result in the flat tables.

Let me give you some explanation about the code that converts the column definition:

    $definition = trim($column['type']);
    if (!preg_match('/([^(]*)(\\((.*)\\))?/', $definition, $matches)) {
        throw Mage::exception(
            'Mage_Core',
            Mage::helper('core')->__("Wrong old style column type definition: {$definition}.")
        );
    }

So basically the preg_match method will give you an array in the $matches variable based on the column definition (stored in $definition).

Example of columns definition usually looks like this:

• int
• varchar(100)
• decimal(12,4)

Those column definitions will respectively give you the following result in the $matches array:

• array('int','int')
• array('varchar(100)','varchar','(100)','100')
• array('decimal(12,4)','decimal','(12,4)','12,4')

Then you've got the $proposedLength variable:

$proposedLength = (isset($matches[3]) && strlen($matches[3])) ? $matches[3] : null;

It is basically equal to the 4th entry in the $matches array if this one is set.

So in your case the value of the $proposeLength should be 12,5.

My suggestion:

Add the following code right after the $proposedLength variable declaration:

Mage::log($column);
Mage::log($matches);
Mage::log($proposedLength);

Try again and check your var/log/system.log file to ensure that the code behaves like it should.