I agree that the data model is suspect. I'm trying to convert from Oracle to Postgres and changing table structures is not really an option for me. I tried casting the null, ... same problem. It does not like the undefined record type as David is saying. I will try his solution and let you know how it goes.
Interestingly a version of this:
CREATE INDEX TX_QSET_DIR_MAP_PRI_URI_TYP_UK
ON tx_question_set_dir_map
USING btree
(question_set2tx_question_set ,uri_type,
(CASE WHEN uri_type = 201900 THEN null::varchar(100)
ELSE question_set_dir_map_key END);
Worked for me. Try it if you are still interested.
Just do proper casting of null (it was varchar(100) in my case).
Regards,
Igor Neyman
Of course, missed “)” at the end:
CREATE INDEX TX_QSET_DIR_MAP_PRI_URI_TYP_UK
ON tx_question_set_dir_map
USING btree
(question_set2tx_question_set ,uri_type,
(CASE WHEN uri_type = 201900 THEN null::varchar(100)
ELSE question_set_dir_map_key END));
Regards,
Igor