install-scriptmagento2migration
According to this dev doc (emphasis mine)
InstallData and InstallSchema scripts, which are executed on a clean (empty) database
UpgradeData and UpgradeSchema incremental scripts, which supplement an existing Magento database
Recurring scripts, which are executed each time you install or upgrade Magento
Does anyone know what feature this development document is talking about? As far as I recall, M2 only had InstallData, InstallSchema, UpgradeData and UpgradeSchema classes.
NB: don't forget that the admin store scope isn't set until dispatching is taking place and a controller extending Mage_Adminhtml_Controller_Action executes (see the adminhtml_controller_action_predispatch_start event and related observer in Mage_Adminhtml_Controller_Action::preDispatch()).
I'm curious about the business logic of having this 'feature'.
You aren't the only one; that said, we may never know unless Moshe or Dima wants to discuss.
Setup scripts execute early in application initialization. The design of this is probably due so that, by the time the rest of the stack is executed, the necessary migrations and other work would be "done" - meaning that the system was ready to use right away even when a module was being installed or upgraded. I'm wondering if the original architects initially ever thought there would be a need for a more initialized system. I'll conjecture that, whereas much of the code assumes that there is a store instance available, the _getDefaultStore() logic ensures that there is a store instance.
Full scope settings are available in 1.4.0.0 and up via data setup scripts.
You can't really upgrade from 1.9 to 2.0.
What you can do is migrate the installation from 1.9 to 2.0
You can find every detail you need in the official documentation here: http://devdocs.magento.com/guides/v2.0/migration/bk-migration-guide.html
Here's a workflow diagram that will give you a good idea of what to do:
Best Answer
Alan, first of all, I want to say thank you for your blog. I learned a lot of Magento thing using it. Thanks a lot.
About the Recurring.php:
These scripts are fired every time u run setup:upgrade cli command and the good example of how it can be used you can find in Magento\Indexer\Setup\Recurring class where Magento_Indexer module checks for newly defined indexers and adds them to indexer_state table.