Magento - FK_CAT_CTGR_PRD_IDX_PRD_ID_CAT_PRD_ENTT_ENTT_ID foreign key constrait when trying to re-index Category Products

Question

The title says it all really - I'm getting an FK constraint failure when trying to re-index Category Products.

Full exception is:

There was a problem with reindexing process.SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails 
(`krcscouk`.`catalog_category_product_index`, CONSTRAINT `FK_CAT_CTGR_PRD_IDX_PRD_ID_CAT_PRD_ENTT_ENTT_ID` FOREIGN KEY (`product_id`) REFERENCES `catalog_product_entity` (`entity_id`) ON DELETE)

I've seen it happen on flat tables before, but never on Category Products, and I'm not sure which tables I'll need to look at to get it playing nicely.

Answer 1

The error has your answer: FK_CAT_CTGR_PRD_IDX_PRD_ID_CAT_PRD_ENTT_ENTT_ID

FK -> Foreign Key
CAT_CTGR_PRD_IDX -> Table Catalog_Category_Product_Index
PRD_ID -> Column Product_ID from the table above
CAT_PRD_ENTT -> Table Catalog_Product_Entity
ENTT_ID -> Column Entity_ID from the table above

So, your problem is that a foreign key from one of these tables to the other fails. Most likely, you have deleted a product and left something in the Catalog_Category_Product_Index. Run the following selects on your database:

SELECT * FROM catalog_category_product_index WHERE product_id NOT IN (SELECT entity_id FROM catalog_product_entity)

Delete those rows from your database and the index process should work.

Answer 2

1. Go to PhpMyAdmin and run this query:

   ALTER TABLE catalog_category_product_index DROP FOREIGN KEY FK_CAT_CTGR_PRD_IDX_PRD_ID_CAT_PRD_ENTT_ENTT_ID

2. Run Reindexing from Magento Admin Panel or from CLI;

3. After the reindexing is complete, run this query from PhpMyAdmin:

   DELETE FROM catalog_category_product_index WHERE product_id not in (select entity_id from catalog_product_entity); ALTER TABLE catalog_category_product_index ADD CONSTRAINT FK_CAT_CTGR_PRD_IDX_PRD_ID_CAT_PRD_ENTT_ENTT_ID FOREIGN KEY (product_id) REFERENCES catalog_product_entity (entity_id) ON DELETE CASCADE ON UPDATE CASCADE;