I am working on Magento Data Migration from 1.9 to 2.2. I customised some code and suppressed some of the possible errors of integrity constraints to execute the tool properly and get the data.

However, I can see some of the rows in catalog_product_entity_varchar are not fully migrated. In the same process of comparing no of rows, I found that some of the tables from source (1.9) database which are starting from m2_cl_ etc.

What are those tables? They all are blank? but Does they have any relations with missing rows and non-migrated data?

  • can you please let me know the git source or other source from where you get the 1.9 magento setup? As By default, there is no table starting from m2_cl_ . It can be talbe with some prefix. Can you please make sure about this?
    – Tejas Vyas
    Dec 28, 2017 at 6:39
  • I have downloaded 1.9 setup from this link. Dec 28, 2017 at 6:56

2 Answers 2


Tables starting from m2_cl are not default tables for Magento 1.9 version but they are created while using Magento data migration tool. They are basically deltalog tables.

More details can be found at this link http://devdocs.magento.com/guides/v2.0/migration/migration-tool-internal-spec.html

  • Thank you Tejas Vyas for sharing this information. Do you know why these deltatables has been created? I can see there is nothing in all such tables. I have suppressed volume check step to disable rollback if volume check failed. I am not clear on the use of delta tables. Dec 28, 2017 at 10:18

Those tables were created by data migration tool. And when you want to do only migrate:data option, it wouldn't be needed anymore.

But if you attempt to migrate:delta option which enables you to migrate only the changes made in Magento 1 since the last time you migrated data(data that customers added via storefront (created orders, reviews, changes in customer profiles, etc.) / all operations with orders in the Magento Admin panel ) on your migration tool, they are must be useful because those tables have the data that have changes since the last migration.

Those tables are composed of entity_id / operation / processed

  • Entity_id : Customer Entity id or Order Entity id
  • Operation : the operation of entity id (DELTE / UPDATE / INSERT)
  • processed : I don't know what it means exactly

After you run migrate:delta, you can see the truncated tables with prefix mc_cl because its data finish to reflect on new change on Magento2

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