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ETL - Oracle Database Features and PL/SQL Techniques Boyan Boev CNsys

ETL - Oracle Database Features and PL/SQL Techniques Boyan Boev CNsys. BGOUG - 2005. Agenda ETL Concepts ETL Process Development - Recommendations Oracle Database Configuration PL/SQL Techniques Database Features Conclusion. BGOUG - 2005. What is ETL? ETL Elements ETL Purpose

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ETL - Oracle Database Features and PL/SQL Techniques Boyan Boev CNsys

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  1. ETL - Oracle Database Features and PL/SQL Techniques Boyan Boev CNsys BGOUG - 2005

  2. Agenda • ETL Concepts • ETL Process Development - Recommendations • Oracle Database Configuration • PL/SQL Techniques • Database Features • Conclusion BGOUG - 2005

  3. What is ETL? • ETL Elements • ETL Purpose • ETL as aPart of Business Intelligence Solution • Types of ETL • Using Tools • Custom PL/SQL Scripts BGOUG - 2005

  4. ETL – Extract, Transform and Load • Extract • Pull the Data From the Source • Transform • Convert the Input Format to the Target Format • Encode any Values • Load • Insert the Transformed Data to the Target Tables BGOUG - 2005

  5. Agenda • ETL Concepts • ETL Process Development - Recommendations • Oracle Database Configuration • PL/SQL Techniques • Database Features • Conclusion BGOUG - 2005

  6. Oracle databaseconfiguration • Don’t use ARCHIVE LOG Mode • Reduce the Amount of I/O Activity • Use NOLOGGING DML Statements ALTER TABLE … NOLOGGING; INSERT /*+ nologging*/ … • Change the stage schema data model • Indexes • Constraints • Triggers BGOUG - 2005

  7. Agenda • ETL Concepts • ETL Process Development - Recommendations • Oracle Database Configuration • PL/SQL Techniques • Database Features • Conclusion BGOUG - 2005

  8. ETL – recommendations • PL/SQL Techniques • Bulk Binding • Collection Types • Pipelined Table Functions • Package Variables • Native Compilation BGOUG - 2005

  9. PL/SQL – Binding • Types of Binds • IN-Binds • OUT-Binds • Bind Options • Single Row Binds • Bulk Binds BGOUG - 2005

  10. Single Row Binds • Cursor For Loop Example: FOR rec INexample_cursor( v_cust_id ) LOOP INSERT INTO cust_action_hist(…) VALUES( … ); END LOOP; END; / DECLARE CURSORexample_cursor( p_id_in NUMBER ) IS SELECT * FROM customer_action WHERE cust_id = p_id_in; v_cust_id NUMBER := 1681; BEGIN BGOUG - 2005

  11. Context Switching BGOUG - 2005

  12. Bulk Binding • IN-Binds • - An Array of Values is passed to SQL Engine • OUT-Binds • - SQL Engine populates a PL/SQL Bind Array • Context Switching once per Batch Instead of Once Per Row • Performance Increase to Up to 15 Times BGOUG - 2005

  13. Bulk Bind Operators • Bulk Collect • Specifying of the LIMIT clause • Be Careful to handle last batch OPEN cursor … LOOP FETCH cursor BULK COLLECT INTO … LIMIT 100; EXIT WHEN cursor%NOTFOUND; END LOOP; BGOUG - 2005

  14. Bulk Bind Operators • FORALL • Bulk DML Operator • Not Looping Construct • PL/SQL table is Referenced in the statement • Handling and Reporting Exceptions • VALUES OF, INDICES OF ( New in Oracle 10g ) FORALL i IN 1..20 INSERT INTO emp2 VALUES (enums(i), names(i), median(sals), ...); BGOUG - 2005

  15. Collection Types • Associative Arrays( PL/SQL Tables ) • PL/SQL type only - not a SQL Type • Easy to Use • Nested Tables • Shared Type BGOUG - 2005

  16. Associative Arrays( PL/SQL Tables ) • automatic element allocation • no need to initialize DECLARE TYPE EmpTabTyp IS TABLE OF employees%ROWTYPE INDEX BY PLS_INTEGER; emp_tab EmpTabTyp; BEGIN SELECT * BULK COLLECT INTO emp_tab FROM employees WHERE employee_id = 100; END; / BGOUG - 2005

  17. Nested Tables • PL/SQL • Example DECLARE TYPE nest_tab_t IS TABLE OF NUMBER; nt nest_tab_t := nest_tab_t(); BEGIN FOR i IN 1..100 LOOP nt.EXTEND; nt(i) := i; END LOOP; END; / BGOUG - 2005

  18. Nested Tables • Global • Example CREATE OR REPLACE TYPE email_demo_obj_t AS OBJECT ( email_id NUMBER, demo_code NUMBER, value VARCHAR2(30) ); /  CREATE OR REPLACE TYPE email_demo_nt_t AS TABLE OF email_demo_obj_t; / BGOUG - 2005

  19. Nested Tables • SQL-Defined Nested Tables • Sorted • Aggregated • Ised in Dynamic In-Lists • Joined with SQL Tables • Joined with other PL/SQL nested tables • Nested Tables Enable Table Functions • TABLE Operator • tell Oracle to treat the Variable like SQL Table • CAST Operator • Explicitly Tells Oracle the Data Type to be used to Handle the Operation - BGOUG - 2005

  20. Nested Tables • Global Nested tables – example: DECLARE eml_dmo_nt email_demo_nt_t := email_demo_nt_t();  BEGIN -- Some logic that populates the nested table … eml_dmo_nt.EXTEND(3); eml_dmo_nt(1) := email_demo_obj_t(45, 3, '23'); eml_dmo_nt(2) := email_demo_obj_t(22, 3, '41'); eml_dmo_nt(3) := email_demo_obj_t(18, 7, 'over_100k'); -- Process the data in assending order of email id. FOR r IN (SELECT * FROM TABLE(CAST(eml_dmo_nt AS email_demo_nt_t)) ORDER BY 1) LOOP dbms_output.put_line(r.email_id || ' ' || r.demo_id); END LOOP; END; / BGOUG - 2005

  21. Table Functions • Data is Buffered in the Local Variables During Function Execution • Pipelined Table Functions • SELECT * FROM plsql_function; BGOUG - 2005

  22. Pipelined Functions - example FUNCTION pipelined_demo( data SYS_REFCURSOR ) RETURN demo_nt_t PIPELINED IS CURSOR demo_cursor IS SELECT demo_obj_t(emp_id, value) FROM emp;  emp_nt demo_nt_t;  BEGIN OPEN email_demo_cur; LOOP EXIT WHEN email_demo_cur%NOTFOUND; FETCH email_demo_cur BULK COLLECT INTO eml_dmo_nt LIMIT 1000;   FOR i IN 1..eml_dmo_nt.COUNT LOOP /* Apply some business logic on the object here, and return a row. */ PIPE ROW (eml_dmo_nt(i)); END LOOP;  END LOOP; RETURN; END; BGOUG - 2005

  23. Package Variables • What are Package Variables • Globally Declared Variables in Package, outsideof a Procedure or Function Definition • Values set by Package Initialization Code • Enable Data Caching BGOUG - 2005

  24. Native Compilation • How it works? • PL/SQL First is Compiled Down To P-Code • C Source Code is Generated from P-Code • Native Compiler is invoked Creating a 'C' Shared Object Library • Subsequent Calls to PL/SQL Object are Run by the 'C' Library • NComp and Performance BGOUG - 2005

  25. Agenda • ETL Concepts • ETL Process Development - Recommendations • Oracle Database Configuration • PL/SQL Techniques • Database Features • Conclusion BGOUG - 2005

  26. ETL – recommendations • Database Featuresand Utilities • External Tables( 9i ) • Transportable Tablespaces • DML Exception Handling( 10g R2 ) • Regular Expressions Support( 10g R1 ) • SQL*Loader • Direct Path INSERT • Parallel DML Statements BGOUG - 2005

  27. Database Features • External tables • File can be Queried as if it is a Real Database Table Can Sort, Aggregate, Filter Rows, etc. • External File Can be Queried in Parallel • Oracle 9i - Read-Only using SQL*Loader Engine • Only read-only access to external files • Oracle 10g - Read-Write using Data Pump Engine • Can do read/write operations with external files • Transportable Tablespaces • Oracle 10g - transport across different platforms BGOUG - 2005

  28. Database Features • DML Exception Handling ( New in 10g R2 ) • Catch the Error and Move On: Error Logging Clause • Enabling: SQL> exec dbms_errlog.CREATE_ERROR_LOG ('ACCOUNTS','ERR_ACCOUNTS'); SQL> insert into accounts select * from accounts_ny log errors into err_accountsreject limit 200; SQL> select ORA_ERR_NUMBER$, ORA_ERR_MESG$, ACC_NO from err_accounts; BGOUG - 2005

  29. Database Features • Regular Expression Support ( New in 10g R1 ) • SQL*Loader • Direct Path Insert • SQL*Loader • CREATE TABLE AS SELECT … • INSERT /*+ APPEND*/ … SELECT • Parallel DML Statements BGOUG - 2005

  30. Agenda • ETL Concepts • ETL Process Development - Recommendations • Oracle Database Configuration • PL/SQL Techniques • Database Features • Conclusion BGOUG - 2005

  31. Example • create package with PIPELINED Function .... FUNCTION transform (new_data SYS_REFCURSOR) RETURN email_demo_nt_t PIPELINED PARALLEL_ENABLE ( PARTITION new_data BY ANY ) IS .... • Transformation is Just a Simple INSERT as SELECT • Elegant solution to Parallel , Transactional Co-Processing INSERT /*+ append nologging*/ INTO ... SELECT /*+ parallel(a,4)*/ FROM .. TABLE( CAST( package.pipe_func_name( select * from table_3 ) as TYPE ) a); BGOUG - 2005

  32. Conclusion • High Perofmance ETL Solution BGOUG - 2005

  33. Recommended Readings – Sites • http://www.oracle.com/technology//index.html • http://rittman.net • http://www.intelligententerprise.com/ • http://asktom.oracle.com • http://www.dbazine.com/datawarehouse • http://dbasupport.com/ BGOUG - 2005

  34. Recommended Readings – Books http://www.amazon.com/exec/obidos/tg/detail/-/0471200247/qid=1129731960/sr=2-1/ref=pd_bbs_b_2_1/104-9260048-7507956?v=glance&s=books BGOUG - 2005

  35. Recommended Readings – Books http://www.amazon.com/exec/obidos/tg/detail/-/0764567578/ref=pd_sim_b_1/104-9260048-7507956?%5Fencoding=UTF8&v=glance BGOUG - 2005

  36. Recommended Readings – Books http://www.amazon.com/exec/obidos/tg/detail/-/1555583350/qid=1129732390/sr=2-2/ref=pd_bbs_b_2_2/104-9260048-7507956?v=glance&s=books BGOUG - 2005

  37. Questions or Comments Boyan Boev b.boev@cnsys.com BGOUG - 2005

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