Magento 2 complained that I should set always_populate_raw_post_data  to -1. Changing the php.ini didn’t help. The solution was to add

php_value always_populate_raw_post_data -1

to my VirtualHost (directly after the AllowOverride of the DocumentRoot-directory config).

To use redis for caching in magento2 I added the following part in app/etc/env.php:

  'cache' => 
  array (
    'frontend' => 
    array (
      'default' => 
      array (
        'backend' => 'Cm_Cache_Backend_Redis',
        'backend_options' => 
        array (
          'server' => '127.0.0.1',
          'port' => '6379',
          'persistent' => '',
          'database' => '0',
          'force_standalone' => '0',
          'connect_retries' => '1',
          'read_timeout' => '10',
          'automatic_cleaning_factor' => '0',
          'compress_data' => '1',
          'compress_tags' => '1',
          'compress_threshold' => '20480',
          'compression_lib' => 'gzip',
        ),
      ),
      'page_cache' => 
      array (
        'backend' => 'Cm_Cache_Backend_Redis',
        'backend_options' => 
        array (
          'server' => '127.0.0.1',
          'port' => '6379',
          'persistent' => '',
          'database' => '1',
          'force_standalone' => '0',
          'connect_retries' => '1',
          'read_timeout' => '10',
          'automatic_cleaning_factor' => '0',
          'compress_data' => '0',
          'compress_tags' => '1',
          'compress_threshold' => '20480',
          'compression_lib' => 'gzip',
        ),
      ),
    ),
  ),

To Update massive amounts of data in magento without going directly into the database I found an interesting piece of code under http://www.mydons.com/writing-custom-magento-shell-script/:

<?php
require_once 'abstract.php';

/**
 * Mydons Inventoryupdate Shell Script
 *
 * @author     Mydons
 */
class Mydons_Shell_Inventory extends Mage_Shell_Abstract {

    /**
     * Run script
     *
     */
    public function run() {

        Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
        $file_handle = fopen("Inventory.csv", "r");

        while (!feof($file_handle)) {
            $line_of_text = fgetcsv($file_handle, 1024);
            $productSku = $line_of_text[0];
            $qty = $line_of_text[1]; 
            $product = Mage::getModel('catalog/product')
                 ->loadByAttribute('sku', $productSku);
            if ($Product) {
                $stockItem = Mage::getModel('cataloginventory/stock_item')
       ->loadByProduct($product);
                // Set Product Stock Data Here
                $stockItem->setData('is_in_stock', 1);
                $stockItem->setData('qty', $qty);
                $stockItem->save();
                echo "Updated Inventory for product " . $productSku . "\n";
            } else {
                echo "Product " . $productSku . " Doesnt Exist \n";
            }
        }
        fclose($file_handle);
    }

    /**
     * Retrieve Usage Help Message
     *
     */
    public function usageHelp() {
        return <<<USAGE
Usage:  php -f inventory.php -- [options]
        php -f inventory.php 


USAGE;
    }

}

$shell = new Mydons_Shell_Inventory();
$shell->run();

I adopted this file to simply print the sku of all products in the shop and count them:

<?php
require_once 'abstract.php';

/**
 * SkuPrinter
 *
 * @author manuel
 */
class Update extends Mage_Shell_Abstract {

    /**
     * Run script
     */
    public function run() {
        Mage::app()->setCurrentStore(Mage_Core_Model_App::ADMIN_STORE_ID);
        $collection = Mage::getResourceModel('catalog/product_collection');
        $i=0;
        foreach ($collection as $product) {
                echo $product->getSku() . "\n";
                $i++;
        }
        print "#products: $i\n";
    }

    /**
     * Retrieve Usage Help Message
     */
    public function usageHelp() {
        return <<<USAGE
Usage:  php -f update.php -- [options]
        php -f update.php
USAGE;
    }

}

$shell = new Update();
$shell->run();

These two examples show how to iterate over all products and how to get a specific product by sku. They have to be placed in ${magento_root}/shell

To speed up updates a bit magento provides the ability to update single fields instead of the whole product as in code snippet one:

$product->setAttributeCode($newValue)
$product->getResource()->saveAttribute($product, 'attribute_Code');

Of course the fastest way is to write SQL queries. Therefor please read into the magento EAV model.

to change the label on the checkout button from “Bestellung abschließen” to “Zahlungspflichtig bestellen” you just have to change the file app/locale/de_DE/Mage_Checkout.csv

Magento creates lots of files and database entries no one really needs. So here is how I tried to clean up the mess – based on this script from the magento site http://www.magentocommerce.com/wiki/groups/227/maintenance_script

First I logged in into the shell and executed the following in the magento directory:

rm -rf var/cache/* var/log/* var/report/* var/session/* 
  var/tmp/* media/import/*

After that I executed the following SQL queries:

truncate table dataflow_batch_export;
truncate table dataflow_batch_import;
truncate table log_customer;
truncate table log_quote;
truncate table log_summary;
truncate table log_summary_type;
truncate table log_url;
truncate table log_url_info;
truncate table log_visitor;
truncate table log_visitor_info;
truncate table log_visitor_online;
truncate table report_event;

If you rename or move the folder containing your magento installation or want to change the domain you won’t reach it anymore because the base_url is saved in the database and used for redirects. So connect to your database and change the URLs saved there:

The URLs are saved under core_config_data and can be retrieved by:

SELECT * FROM core_config_data WHERE path LIKE '%base_url';

Then just adapt the result and don’t forget to clean the cache.

This problem should be fixable by changing app/code/core/Mage/Eav/Model/Resource/Entity/Attribute/Option/Collection.php line 117. Just insert “main_table.” (without “) before option_id. The line shoul look like the following after that:

return $this->addFieldToFilter('main_table.option_id', array('in' => $optionId));