使用python将clob插入oracle时,如何调用dbms_crypto.hash?

我在甲骨文中存储clobs。为了加快查找相同clob的速度,我想引入clob的散列值。到目前为止我试过的是

1. 插入clob
2. 根据存储的CLOB更新哈希值。

如何在一个操作中代替两个操作?

#!/usr/local/bin/python3
import cx_Oracle

con = cx_Oracle.connect('scott/tiger@localhost:1512/ORCLPDB1', encoding="UTF-8")
cursor = con.cursor()
cursor.execute("CREATE TABLE t (id NUMBER, script CLOB, script_hash RAW(32))")  

my_text = '$'*2**10

statement = "INSERT INTO t (id, script) VALUES (:my_id, :my_clob)"
cursor.execute(statement, (1, my_text))

statement = """
    UPDATE t 
       SET script_hash = DBMS_CRYPTO.HASH(script, 2) 
     WHERE id = :my_id"""
cursor.execute(statement, {'my_id': 1})

con.commit()    
con.close()

这不起作用:

statement = """
   INSERT INTO t (id, script, script_hash) 
   VALUES (:my_id, :my_clob, DBMS_CRYPTO.HASH(:my_clob, 2))"""
cursor.execute(statement, (2, my_text, my_text))

# cx_Oracle.DatabaseError: ORA-01465: invalid hex number

(Oracle 12.2使用Python和CX_Oracle 6.3)