Magento save your thumb, small_image, and thumbnail in the catalog_product_entity_varchar table.
Since Magento uses the eav architecture, the thumbnail, small_image and large image are stored in catalog_product_entity_varchar with the link identifiers from the eav_attribute table.
In the catalog_product_entity_varchar table, entity_id represents the product identifier, and attribute_id represents the reference identifier from the attribute table.
Typically, the id 74 attribute is image , 75- small_image and 76- thumbnail . You can check the corresponding identifier in the eav_attribute table.
For example, if a product with entity_id 1,
If we check the value for the catalog_product_entity_varchar table, the value with respect to id 74 represents its image, 75 represents its small image, and 76 represents its thumbnail.
Hope this helps.
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