Imagine table like this one (id of the product and column with categories the product belongs to, separated by pipe):

You don't necessary know how many categories there could be, it differs for some types of products. Probably you want to have a table, where each product has all of its categories on different rows, so you're able to do more with it. Before you'll be begging some R/Python guy/girl to parse it for you, you can try to use this short SQL script:

SELECT
  "product_id"                    AS "object_id",
  trim("c".value :: VARCHAR(100)) AS "category"
FROM "categories",
    LATERAL flatten(input => split("categories", '|')) "c";

Voila:

Well, that was quick, right?

Enjoy!