通过创建 Secure Access Policies可以对vertica中的某一列数据进行加密：

CREATE ACCESS POLICY ON [schema][tablename]FOR COLUMN columnnameexpression[ENABLE/DISABLE];

例如：

CREATE ACCESS POLICY ON customers_tableFOR COLUMN SSNCASEWHEN ENABLED_ROLE('manager') THEN SSNWHEN ENABLED_ROLE('operator') THEN SUBSTR(SSN, 8, 4)ELSE NULLENDENABLE;

ALTER ACCESS POLICYALTER ACCESS POLICY ON tablename.. .FOR COLUMN columnname... expression... [ENABLE | DISABLE];... | FOR COLUMN columname...   COPY TO tablename;DROP ACCESS POLICYDROP ACCESS POLICY ON tablenameFOR COLUMN columnname;

如果表中存在策略的话，那么drop table 时会报错：