The "certificate_identity" table existed in the original crt.sh database that ran out of 32-bit certificate IDs in late 2019 (see
https://groups.google.com/g/crtsh/c/DM8SI-qsE8E/m/J_ndSkroBgAJ). To avoid breaking anyone's applications that were using "certificate_identity", we kept one instance of the old DB lying around, which was connected to the new DB via postgres_fdw. "certificate_identity" became a view on the new DB that accessed the data from the old DB. The intention was to announce a deprecation date for "certificate_identity", but...oops...I never got around to it.
So this isn't the orderly deprecation I had intended, but...given that "certificate_identity" has not been getting any new data since late 2019, and given that it's been broken for several days, I'm not going to resurrect it now.
Instead, "certificate_identity" will now be a function-based view that raises an exception with the following message:
Sorry, the "certificate_identity" table has been superseded by a Full Text Search index on the "certificate" table.