Oracle Magazine, July/August 2017
Database Developer and DBA ETL Another external table DDL risk example is the filename attribute In my example above the format of the filename emp 2016 01 01 dat suggests that this filename may need to be adjusted in the external table definition every day as a new employee file is generated with a fresh date stamp in the name But demanding a complete suite of checks and balances for such a small DDL change would be overkill MORE FLEXIBILITY WITH ORACLE DATABASE 12c RELEASE 2 Oracle Database 12c Release 2 recognizes that there are some modifications to external table definitions that can be considered a lower risk exercise than would be the case with more typical DDL changes to tables In Oracle Database 12c Release 2 without any DDL changes to the table some external table parameters can be modified directly within the execution of a query against that external table To solve the problem of my missing REJECT LIMIT clause for example I can add an EXTERNAL MODIFY clause directly to my SELECT statement ORACLE MAGAZINE JULY AUGUST 2017 98 SQL select from ext_ emp 2 external modify reject limit unlimited EMPNO ENAME JOB MGR HIREDATE SAL 7499 ALLEN SALESMAN 7698 20 FEB 81 1600 7521 WARD SALESMAN 7698 22 FEB 81 1250 7566 JONES MANAGER 7839 02 APR 81 2975
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