I found out while writing my Esprinet importer for Magento.

I think that using Magento API is the cleanest way to do every import operation but importing something like 70.000 products was absolutely TOO SLOW so I had to look for something else…

Magmi (which is released under the ) does everything using SQL queries and it’s blazing fast! It also features a few really useful plugins, the one I like the most are:

• Category importer: you can type category names in CSV instead of category ids, really nice. It also creates parent categories if you use the “parent/child” syntax.
• Optimizer: runs some MySQL tables optimization before importing.
• Magento reindexer: updates all (or just some) Magento indexes, couldn’t live without it!

What I didn’t like?

• Using “/” for the category importer separator, I’ve a lot of categories with the “/” char in the name, so I hat to patch the plugin to use “->” instead of “/”. I think it could be better in any case but for the maximum flexibility it should be a part of the configuration options
• I couldn’t find any documentation about the CLI usage
• Using Magmi CLI it seems to me that the import progress file isn’t updated the right way

Anyway the Magmi team did a great job, hope it will continue to be maintained for future Magento releases.