Indexers and indexing modes in Magento

Indexers are one of the most important performance tools in Magento. They create specialized database tables that store optimized data, which makes executing database queries much faster.

Indexers are best thought of as simple lookup tables. When we break them down, these tables simply contain references to aggregate data from other tables. This makes them similar to the indexes in the back of a book; just look up the specific topic to get the exact page they are on.

How indexers improve performance

Without indexing, Magento would need to perform complex lookups with expensive...