Prevent column validation exceptions caused by Oracle CLOB/NCLOB columns used for JSON

[nj1973]

Test case

Oracle:

CREATE TABLE dvt_test.tab_json
(
  id VARCHAR2(10) NOT NULL PRIMARY KEY
, col_json1 CLOB
, col_json2 CLOB
);
ALTER TABLE dvt_test.tab_json ADD CONSTRAINT tab_json_chk1 CHECK (col_json1 IS JSON) ENABLE;
ALTER TABLE dvt_test.tab_json ADD CONSTRAINT tab_json_chk2 CHECK (col_json2 IS JSON) ENABLE;
INSERT INTO dvt_test.tab_json VALUES (1,'{"a": 1}','{"a": 1}');
COMMIT;

PostgreSQL:

CREATE TABLE dvt_test.tab_json
(
  id varchar(10) NOT NULL PRIMARY KEY
, col_json1 json
, col_json2 jsonb
);
INSERT INTO dvt_test.tab_json VALUES (1,'{"a": 1}','{"a": 1}');

Column validation
DVT command Oracle vs PostgreSQL:

$ data-validation validate column -sc ora_local -tc pg_local -tbls="dvt_test.tab_json" --count '*' --sum '*' --min '*' --max '*' --avg '*' --std '*' --filter-status fail
...
sqlalchemy.exc.ProgrammingError: (psycopg2.errors.UndefinedFunction) function length(json) does not exist
LINE 2: ..._json2 AS col_json2, length(t1.id) AS length__id, length(t1....
                                                             ^
HINT:  No function matches the given name and argument types. You might need to add explicit type casts.

The problem is that Oracle stores JSON data in a CLOB.

Row validation
DVT command Oracle vs PostgreSQL:

$ data-validation validate row -sc ora_local -tc pg_local -tbls="dvt_test.tab_json" -pk=id --hash=col_json1,col_json2
...
  File "/usr/local/google/home/neiljohnson/github/professional-services-data-validator/.venv/lib/python3.11/site-packages/sqlalchemy/engine/default.py", line 736, in do_execute
    cursor.execute(statement, parameters)
cx_Oracle.DatabaseError: ORA-00932: inconsistent datatypes: expected CLOB got CHAR

[nj1973]

We should add the test columns above to the dvt_ora2pg_types integration test.

[nj1973]

I feel this issue needs to be split into two.

1. Prevent Oracle CLOB/NCLOB from generating exceptions when used in a normal context. This is the higher priority part to prevent command failures.
2. Look at general JSON support and tests across all validation types. Including spotting Oracle CLOB/NCLOB used for JSON data. This is lower priority feature request.

I will complete item 1 on this issue now, I've opened #1338 for item 2 above.