Perhaps your experience is different from mine but JSON string columns are very common in ClickHouse. A common schema idiom is to put the JSON in a string and then selectively materialize commonly queried properties into regular table columns. You can index the column with a bloom filter index to do needle-in-a-haystack searches on the entire row's data. Bloom filters are tricky to parameterize correctly but I have seen this approach used to good effect in very large applications.