Just stumbled over a blog post from Steven Feuerstein. He talks about not using DBMS_OUTPUT in our code directly but through a package that allows to turn it on/off and but the output in a table or as indented with DBMS_OUTPUT on screen. You may find Steven’s article here.
Today I rediscovered a feature of Oracle that is in since 10i. In 12c it was extended.
What is it all about? I am able to use dumps that where created with data pump as a file for external tables. But not enough I can also create an external table using CTAS (create table as select). Let’s see the simple steps to do so.
First I need a directory to write into. There are two options. First I grant the right as seen below to the user in need or I create the directory with the privileged user and grant the right to the directory to the user.
GRANT CREATE ANY DIRECTORY TO SCOTT;
As SCOTT I may now create the need directory. Oracle needs access to that directory.
CREATE OR REPLACE DIRECTORY ext_dir AS '/u01/userhome/oracle/ext_tables'; Directory EXT_DIR created.
Next I may create the external table with the data pump access driver. This is done with “TYPE ORACLE_DATAPUMP”.
CREATE TABLE ext_emp ORGANIZATION EXTERNAL ( TYPE ORACLE_DATAPUMP DEFAULT DIRECTORY ext_dir LOCATION ('ext_emp.dmp') ) AS SELECT * FROM emp; Table EXT_EMP created.
Now I can already access the external table
SELECT * FROM ext_emp; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ------ ---------- --------- ------ --------- ------ ------ ---------- 7369 SMITH CLERK 7902 17-DEC-80 800 20 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30 7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 7566 JONES MANAGER 7839 02-APR-81 2975 20 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 7782 CLARK MANAGER 7839 09-JUN-81 2450 10 7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7839 KING PRESIDENT 17-NOV-81 5000 10 7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30 7876 ADAMS CLERK 7788 23-MAY-87 1100 20 7900 JAMES CLERK 7698 03-DEC-81 950 30 7902 FORD ANALYST 7566 03-DEC-81 3000 20 7934 MILLER CLERK 7782 23-JAN-82 1300 10 14 rows selected.
The definition is the same as the table was.
DESC ext_emp Name Null? Type -------- ----- ------------ EMPNO NUMBER(4) ENAME VARCHAR2(10) JOB VARCHAR2(9) MGR NUMBER(4) HIREDATE DATE SAL NUMBER(7,2) COMM NUMBER(7,2) DEPTNO NUMBER(2)
Some additional thoughts:
- No change of data possible. Once created it is read only
- Parallel is possible
- Compression is possible but only with “Advanced Compression”
It is a simple way to use external tables. No need to think about the format. No need to think about conversions. It is all done for you. Isn’t this great.
For more information just visit:
Oracle External Table Documentation
Oracle External Table Documentation – Oracle Data Pump Access Driver
as always I like to know how things are progressing especially when they are running long. This is also the case with ROLLBACK.
Here is a statement that helped me:
SELECT s.username, s.sid, s.serial#, t.used_ublk, t.used_urec, rs.segment_name, r.rssize, r.status FROM v$transaction t, v$session s, v$rollstat r, dba_rollback_segs rs WHERE s.saddr = t.ses_addr AND t.xidusn = r.usn AND rs.segment_id = t.xidusn ORDER BY t.used_ublk DESC /
I am interested if there are better options.
My prefered language in Oracle Data Modeler is English.
If the language is not English here are the steps to change this:
Add the line following line to the file datamodeler.conf in the directory datamodeler\bin\. On a Mac it is in the OracleDataModeler-VersionNumer.app in the folder Contents\Resources\datamodeler\datamodeler\bin\
Restart Oracle Data Modeler.
Got the tip on the webpage:
Memosoup.com – change interface language
Cool must read
Analytic Views, in combination with Attribute Dimensions and Hierarchies, are very useful for ad-hoc queries in a Star Schema. But how about the performance of this Oracle 12.2 feature? I wanted to know it and analyzed the execution plans of some simple queries.
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Ein Kollege von mir hat ein tolles DWH Buch veröffentlicht. Schaut doch mal rein. Ich kann es nur empfehlen!
This is my speech at DOAG 2015.
I documented my 1. steps with Impala. Showing how to get data into Hadoop and Impala. And very important how to get it out again.