dwh material
DESCRIPTION
DWH MaterialTRANSCRIPT
Automation of Candidate Extract and Load Process
DWH MaterialVersion 1.0REVISION HISTORY
The following table reflects all changes to this document.
DateAuthor / ContributorVersionReason for Change
01-Nov-20041.0Initial Document
14-Sep-20101.1Updated Document
Table of Contents
41Introduction
41.1Purpose
42ORACLE
42.1DEFINATIONS
5NORMALIZATION:
5First Normal Form:
5Second Normal Form:
5Third Normal Form:
6Boyce-Codd Normal Form:
6Fourth Normal Form:
6ORACLE SET OF STATEMENTS:
6Data Definition Language :(DDL)
6Data Manipulation Language (DML)
7Data Querying Language (DQL)
7Data Control Language (DCL)
7Transactional Control Language (TCL)
7Syntaxes:
9ORACLE JOINS:
10Equi Join/Inner Join:
10Non-Equi Join
10Self Join
11Natural Join
11Cross Join
11Outer Join
11Left Outer Join
12Right Outer Join
12Full Outer Join
12Whats the difference between View and Materialized View?
13View:
13Materialized View:
14Inline view:
19Indexes:
19Why hints Require?
22Explain Plan:
23Store Procedure:
24Packages:
24Triggers:
26Data files Overview:
272.2IMPORTANT QUERIES
303DWH CONCEPTS
30What is BI?
534ETL-INFORMATICA
534.1Informatica Overview
924.2Informatica Scenarios:
994.3Development Guidelines
1034.4Performance Tips
1054.5Unit Test Cases (UTP):
1085UNIX
Detailed Design Document1 Introduction
1.1 Purpose
The purpose of this document is to provide the detailed information about DWH Concepts and Informatica based on real-time training.2 ORACLE2.1 DEFINATIONSOrganizations can store data on various media and in different formats, such as a hard-copy document
in a filing cabinet or data stored in electronic spreadsheets or in databases.
A database is an organized collection of information.
To manage databases, you need database management systems (DBMS). A DBMS is a program that
stores, retrieves, and modifies data in the database on request. There are four main types of databases:
hierarchical, network, relational, and more recently object relational(ORDBMS).
NORMALIZATION:
Some Oracle databases were modeled according to the rules of normalization that were intended to eliminate redundancy.
Obviously, the rules of normalization are required to understand your relationships and functional dependencies
First Normal Form:
A row is in first normal form (1NF) if all underlying domains contain atomic values only.
Eliminate duplicative columns from the same table.
Create separate tables for each group of related data and identify each row with a unique column or set of columns (the primary key).
Second Normal Form:
An entity is in Second Normal Form (2NF) when it meets the requirement of being in First Normal Form (1NF) and additionally:
Does not have a composite primary key. Meaning that the primary key can not be subdivided into separate logical entities.
All the non-key columns are functionally dependent on the entire primary key.
A row is in second normal form if, and only if, it is in first normal form and every non-key attribute is fully dependent on the key.
2NF eliminates functional dependencies on a partial key by putting the fields in a separate table from those that are dependent on the whole key. An example is resolving many: many relationships using an intersecting entity.
Third Normal Form:
An entity is in Third Normal Form (3NF) when it meets the requirement of being in Second Normal Form (2NF) and additionally:
Functional dependencies on non-key fields are eliminated by putting them in a separate table. At this level, all non-key fields are dependent on the primary key.
A row is in third normal form if and only if it is in second normal form and if attributes that do not contribute to a description of the primary key are move into a separate table. An example is creating look-up tables.Boyce-Codd Normal Form:
Boyce Codd Normal Form (BCNF) is a further refinement of 3NF. In his later writings Codd refers to BCNF as 3NF. A row is in Boyce Codd normal form if, and only if, every determinant is a candidate key. Most entities in 3NF are already in BCNF.
Fourth Normal Form:
An entity is in Fourth Normal Form (4NF) when it meets the requirement of being in Third Normal Form (3NF) and additionally:
Has no multiple sets of multi-valued dependencies. In other words, 4NF states that no entity can have more than a single one-to-many relationship.
ORACLE SET OF STATEMENTS:
Data Definition Language :(DDL)
Create
Alter
Drop
Truncate
Data Manipulation Language (DML)
Insert
Update
Delete
Data Querying Language (DQL)
Select
Data Control Language (DCL)
Grant
Revoke
Transactional Control Language (TCL)
Commit
Rollback
Save point
Syntaxes:
CREATE OR REPLACE SYNONYM HZ_PARTIES FOR SCOTT.HZ_PARTIES
CREATE DATABASE LINK CAASEDW CONNECT TO ITO_ASA IDENTIFIED BY exact123 USING ' CAASEDW Materialized View syntax:
CREATE MATERIALIZED VIEW EBIBDRO.HWMD_MTH_ALL_METRICS_CURR_VIEW
REFRESH COMPLETESTART WITH sysdateNEXT TRUNC(SYSDATE+1)+ 4/24
WITH PRIMARY KEYAS
select * from HWMD_MTH_ALL_METRICS_CURR_VW;Another Method to refresh:
DBMS_MVIEW.REFRESH('MV_COMPLEX', 'C');Case Statement:
Select NAME,
(CASE
WHEN (CLASS_CODE = 'Subscription')
THEN ATTRIBUTE_CATEGORY
ELSE TASK_TYPE
END) TASK_TYPE,
CURRENCY_CODE
From EMPDecode()
Select empname,Decode(address,HYD,Hyderabad,
Bang, Bangalore, address) as address from emp;
Procedure:
CREATE OR REPLACE PROCEDURE Update_bal (
cust_id_IN In NUMBER,
amount_IN In NUMBER DEFAULT 1) AS
BEGIN
Update account_tbl Set amount= amount_IN where cust_id= cust_id_IN
End
Trigger:
CREATE OR REPLACE TRIGGER EMP_AUR AFTER/BEFORE UPDATE ON EMP REFERENCING
NEW AS NEW
OLD AS OLD
FOR EACH ROW
DECLARE
BEGIN
IF (:NEW.last_upd_tmst :OLD.last_upd_tmst) THEN
-- Insert into Control table record
Insert into table emp_w values('wrk',sysdate)
ELSE
-- Exec procedure
Exec update_sysdate()
END;
ORACLE JOINS:
Equi join
Non-equi join
Self join
Natural join
Cross join
Outer join
Left outer
Right outer
Full outer
Equi Join/Inner Join:
SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno=d.deptno;
USING CLAUSE
SQL> select empno,ename,job ,dname,loc from emp e join dept d using(deptno);
ON CLAUSE
SQL> select empno,ename,job,dname,loc from emp e join dept d on(e.deptno=d.deptno);
Non-Equi JoinA join which contains an operator other than = in the joins condition.
Ex: SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno > d.deptno;
Self JoinJoining the table itself is called self join.
Ex1: SQL> select e1.empno,e2.ename ,e1.job,e2.deptno from emp e1,emp e2 where e1.mgr=e2.empno;
Ex2:
SELECT worker. employee_id, manager.last_name as manger name
FROM employees worker, employees manager
WHERE worker.manager_id = manager.employee_id ;
Natural JoinNatural join compares all the common columns.
Ex: SQL> select empno,ename,job,dname,loc from emp natural join dept;
Cross JoinThis will gives the cross product.
Ex: SQL> select empno,ename,job,dname,loc from emp cross join dept;
Outer JoinOuter join gives the non-matching records along with matching records.
Left Outer JoinThis will display the all matching records and the records which are in left hand side table those that are not in right hand side table.
Ex: SQL> select empno,ename,job,dname,loc from emp e left outer join dept d on(e.deptno=d.deptno);
Or
SQL> select empno,ename,job,dname,loc from emp e,dept d where
e.deptno=d.deptno(+);
Right Outer JoinThis will display the all matching records and the records which are in right hand side table those that are not in left hand side table.
Ex: SQL> select empno,ename,job,dname,loc from emp e right outer join dept d on(e.deptno=d.deptno);
Or
SQL> select empno,ename,job,dname,loc from emp e,dept d where e.deptno(+) = d.deptno;
Full Outer JoinThis will display the all matching records and the non-matching records from both tables.
Ex: SQL> select empno,ename,job,dname,loc from emp e full outer join dept d on(e.deptno=d.deptno);
OR
SQL> select p.part_id, s.supplier_name
2 from part p, supplier s
3 where p.supplier_id = s.supplier_id (+)
4 union
5 select p.part_id, s.supplier_name
6 from part p, supplier s
7 where p.supplier_id (+) = s.supplier_id;
Whats the difference between View and Materialized View?
View:
Why Use Views?
To restrict data access
To make complex queries easy
To provide data independence
A simple view is one that:
Derives data from only one table
Contains no functions or groups of data
Can perform DML operations through the view.
A complex view is one that:
Derives data from many tables
Contains functions or groups of data
Does not always allow DML operations through the view
A view has a logical existence but a materialized view has
a physical existence.Moreover a materialized view can be
Indexed, analysed and so on....that is all the things that
we can do with a table can also be done with a materialized
view.
We can keep aggregated data into materialized view. we can schedule the MV to refresh but table cant.MV can be created based on multiple tables.
Materialized View:
In DWH materialized views are very essential because in reporting side if we do aggregate calculations as per the business requirement report performance would be de graded. So to improve report performance rather than doing report calculations and joins at reporting side if we put same logic in the MV then we can directly select the data from MV without any joins and aggregations. We can also schedule MV (Materialize View).Inline view:
If we write a select statement in from clause that is nothing but inline view.
Ex:
Get dept wise max sal along with empname and emp no.
Select a.empname, a.empno, b.sal, b.deptno
From EMP a, (Select max (sal) sal, deptno from EMP group by deptno) b
Where
a.sal=b.sal and
a.deptno=b.deptno
What is the difference between view and materialized view?
ViewMaterialized view
A view has a logical existence. It does not contain data.A materialized view has a physical existence.
Its not a database object.It is a database object.
We cannot perform DML operation on view.We can perform DML operation on materialized view.
When we do select * from view it will fetch the data from base table.When we do select * from materialized view it will fetch the data from materialized view.
In view we cannot schedule to refresh.In materialized view we can schedule to refresh.
We can keep aggregated data into materialized view. Materialized view can be created based on multiple tables.
What is the Difference between Delete, Truncate and Drop?
DELETE
The DELETE command is used to remove rows from a table. A WHERE clause can be used to only remove some rows. If no WHERE condition is specified, all rows will be removed. After performing a DELETE operation you need to COMMIT or ROLLBACK the transaction to make the change permanent or to undo it.
TRUNCATE
TRUNCATE removes all rows from a table. The operation cannot be rolled back. As such, TRUCATE is faster and doesn't use as much undo space as a DELETE.
DROP
The DROP command removes a table from the database. All the tables' rows, indexes and privileges will also be removed. The operation cannot be rolled back.
Difference between Rowid and Rownum?ROWID
A globally unique identifier for a row in a database. It is created at the time the row is inserted into a table, and destroyed when it is removed from a table.'BBBBBBBB.RRRR.FFFF' where BBBBBBBB is the block number, RRRR is the slot(row) number, and FFFF is a file number.
ROWNUM
For each row returned by a query, the ROWNUM pseudo column returns a number indicating the order in which Oracle selects the row from a table or set of joined rows. The first row selected has a ROWNUM of 1, the second has 2, and so on.
You can use ROWNUM to limit the number of rows returned by a query, as in this example:
SELECT * FROM employees WHERE ROWNUM < 10;RowidRow-num
Rowid is an oracle internal id that is allocated every time a new record is inserted in a table. This ID is unique and cannot be changed by the user.Row-num is a row number returned by a select statement.
Rowid is permanent.Row-num is temporary.
Rowid is a globally unique identifier for a row in a database. It is created at the time the row is inserted into the table, and destroyed when it is removed from a table.The row-num pseudocoloumn returns a number indicating the order in which oracle selects the row from a table or set of joined rows.
Order of where and having:
SELECT column, group_function
FROM table
[WHERE condition]
[GROUP BY group_by_expression]
[HAVING group_condition]
[ORDER BY column];
The WHERE clause cannot be used to restrict groups. you use the
HAVING clause to restrict groups.
Differences between where clause and having clause
Where clauseHaving clause
Both where and having clause can be used to filter the data.
Where as in where clause it is not mandatory.But having clause we need to use it with the group by.
Where clause applies to the individual rows.Where as having clause is used to test some condition on the group rather than on individual rows.
Where clause is used to restrict rows.But having clause is used to restrict groups.
Restrict normal query by whereRestrict group by function by having
In where clause every record is filtered based on where.In having clause it is with aggregate records (group by functions).
MERGE Statement
You can use merge command to perform insert and update in a single command.
Ex: Merge into student1 s1
Using (select * from student2) s2
On (s1.no=s2.no)
When matched then
Update set marks = s2.marks
When not matched then
Insert (s1.no, s1.name, s1.marks) Values (s2.no, s2.name, s2.marks);
What is the difference between sub-query & co-related sub query?A sub query is executed once for the parent statement
whereas the correlated sub query is executed once for each
row of the parent query.
Sub Query:
Example:
Select deptno, ename, sal from emp a where sal in (select sal from Grade where sal_grade=A or sal_grade=B)
Co-Related Sun query:
Example:
Find all employees who earn more than the average salary in their department.
SELECT last-named, salary, department_id FROM employees A
WHERE salary > (SELECT AVG (salary)
FROM employees B WHERE B.department_id =A.department_id
Group by B.department_id)
EXISTS:
The EXISTS operator tests for existence of rows in
the results set of the subquery.
Select dname from dept where exists (select 1 from EMPwhere dept.deptno= emp.deptno);
Sub-queryCo-related sub-query
A sub-query is executed once for the parent QueryWhere as co-related sub-query is executed once for each row of the parent query.
Example:
Select * from emp where deptno in (select deptno from dept);Example:
Select a.* from emp e where sal >= (select avg(sal) from emp a where a.deptno=e.deptno group by a.deptno);
Indexes:
1. Bitmap indexes are most appropriate for columns having low distinct valuessuch as GENDER, MARITAL_STATUS, and RELATION. This assumption is not completely accurate, however. In reality, a bitmap index is always advisable for systems in which data is not frequently updated by many concurrent systems. In fact, as I'll demonstrate here, a bitmap index on a column with 100-percent unique values (a column candidate for primary key) is as efficient as a B-tree index.
2. When to Create an Index
3. You should create an index if:
4. A column contains a wide range of values5. A column contains a large number of null values6. One or more columns are frequently used together in a WHERE clause or a join condition7. The table is large and most queries are expected to retrieve less than 2 to 4 percent of the rows
8. By default if u create index that is nothing but b-tree index.
Why hints Require?It is a perfect valid question to ask why hints should be used. Oracle comes with an optimizer that promises to optimize a query's execution plan. When this optimizer is really doing a good job, no hints should be required at all.
Sometimes, however, the characteristics of the data in the database are changing rapidly, so that the optimizer (or more accuratly, its statistics) are out of date. In this case, a hint could help.
You should first get the explain plan of your SQL and determine what changes can be done to make the code operate without using hints if possible. However, hints such as ORDERED, LEADING, INDEX, FULL, and the various AJ and SJ hints can take a wild optimizer and give you optimal performance
Tables analyze and update Analyze Statement
The ANALYZE statement can be used to gather statistics for a specific table, index or cluster. The statistics can be computed exactly, or estimated based on a specific number of rows, or a percentage of rows:
ANALYZE TABLE employees COMPUTE STATISTICS;
ANALYZE TABLE employees ESTIMATE STATISTICS SAMPLE 15 PERCENT;
EXEC DBMS_STATS.gather_table_stats('SCOTT', 'EMPLOYEES');
Automatic Optimizer Statistics Collection
By default Oracle 10g automatically gathers optimizer statistics using a scheduled job called GATHER_STATS_JOB. By default this job runs within maintenance windows between 10 P.M. to 6 A.M. week nights and all day on weekends. The job calls the DBMS_STATS.GATHER_DATABASE_STATS_JOB_PROC internal procedure which gathers statistics for tables with either empty or stale statistics, similar to the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option. The main difference is that the internal job prioritizes the work such that tables most urgently requiring statistics updates are processed first.
Hint categories:
Hints can be categorized as follows:
ALL_ROWSOne of the hints that 'invokes' the Cost based optimizer ALL_ROWS is usually used for batch processing or data warehousing systems.
(/*+ ALL_ROWS */)
FIRST_ROWSOne of the hints that 'invokes' the Cost based optimizer FIRST_ROWS is usually used for OLTP systems.
(/*+ FIRST_ROWS */)
CHOOSEOne of the hints that 'invokes' the Cost based optimizer This hint lets the server choose (between ALL_ROWS and FIRST_ROWS, based on statistics gathered.
Hints for Join Orders,
Hints for Join Operations,
Hints for Parallel Execution, (/*+ parallel(a,4) */) specify degree either 2 or 4 or 16
Additional Hints
HASHHashes one table (full scan) and creates a hash index for that table. Then hashes other table and uses hash index to find corresponding records. Therefore not suitable for < or > join conditions.
/*+ use_hash */
Use Hint to force using index
SELECT /*+INDEX (TABLE_NAME INDEX_NAME) */ COL1,COL2 FROM TABLE_NAME
Select ( /*+ hash */ ) empno from
ORDERED-( This hint forces tables to be joined in the order specified. If you know table X has fewer rows, then ordering it first may speed execution in a join.
PARALLEL (table, instances)(This specifies the operation is to be done in parallel.
If index is not able to create then will go for /*+ parallel(table, 8)*/-----For select and update example---in where clase like st,not in ,>,< , then we will use.
Explain Plan:
Explain plan will tell us whether the query properly using indexes or not.whatis the cost of the table whether it is doing full table scan or not, based on these statistics we can tune the query.
The explain plan process stores data in the PLAN_TABLE. This table can be located in the current schema or a shared schema and is created using in SQL*Plus as follows:
SQL> CONN sys/password AS SYSDBA
Connected
SQL> @$ORACLE_HOME/rdbms/admin/utlxplan.sql
SQL> GRANT ALL ON sys.plan_table TO public;
SQL> CREATE PUBLIC SYNONYM plan_table FOR sys.plan_table;
What is your tuning approach if SQL query taking long time? Or how do u tune SQL query?
If query taking long time then First will run the query in Explain Plan, The explain plan process stores data in the PLAN_TABLE.
it will give us execution plan of the query like whether the query is using the relevant indexes on the joining columns or indexes to support the query are missing.
If joining columns doesnt have index then it will do the full table scan if it is full table scan the cost will be more then will create the indexes on the joining columns and will run the query it should give better performance and also needs to analyze the tables if analyzation happened long back. The ANALYZE statement can be used to gather statistics for a specific table, index or cluster using
ANALYZE TABLE employees COMPUTE STATISTICS;
If still have performance issue then will use HINTS, hint is nothing but a clue. We can use hints like
ALL_ROWSOne of the hints that 'invokes' the Cost based optimizer ALL_ROWS is usually used for batch processing or data warehousing systems.
(/*+ ALL_ROWS */)
FIRST_ROWSOne of the hints that 'invokes' the Cost based optimizer FIRST_ROWS is usually used for OLTP systems.
(/*+ FIRST_ROWS */)
CHOOSEOne of the hints that 'invokes' the Cost based optimizer This hint lets the server choose (between ALL_ROWS and FIRST_ROWS, based on statistics gathered.
HASHHashes one table (full scan) and creates a hash index for that table. Then hashes other table and uses hash index to find corresponding records. Therefore not suitable for < or > join conditions.
/*+ use_hash */
Hints are most useful to optimize the query performance.
Store Procedure:
What are the differences between stored procedures and triggers?
Stored procedure normally used for performing tasksBut the Trigger normally used for tracing and auditing logs.
Stored procedures should be called explicitly by the user in order to executeBut the Trigger should be called implicitly based on the events defined in the table.
Stored Procedure can run independentlyBut the Trigger should be part of any DML events on the table.
Stored procedure can be executed from the TriggerBut the Trigger cannot be executed from the Stored procedures.
Stored Procedures can have parameters.But the Trigger cannot have any parameters.
Stored procedures are compiled collection of programs or SQL statements in the database.
Using stored procedure we can access and modify data present in many tables.
Also a stored procedure is not associated with any particular database object.
But triggers are event-driven special procedures which are attached to a specific database object say a table.
Stored procedures are not automatically run and they have to be called explicitly by the user. But triggers get executed when the particular event associated with the event gets fired.
Packages:Packages provide a method of encapsulating related procedures, functions, and associated cursors and variables together as a unit in the database.
package that contains several procedures and functions that process related to same transactions.
A package is a group of related procedures and functions, together with the cursors and variables they use,
Packages provide a method of encapsulating related procedures, functions, and associated cursors and variables together as a unit in the database.
Triggers:Oracle lets you define procedures called triggers that run implicitly when an INSERT, UPDATE, or DELETE statement is issued against the associated table
Triggers are similar to stored procedures. A trigger stored in the database can include SQL and PL/SQL
Types of Triggers
This section describes the different types of triggers:
Row Triggers and Statement Triggers
BEFORE and AFTER Triggers
INSTEAD OF Triggers
Triggers on System Events and User Events
Row Triggers
A row trigger is fired each time the table is affected by the triggering statement. For example, if an UPDATE statement updates multiple rows of a table, a row trigger is fired once for each row affected by the UPDATE statement. If a triggering statement affects no rows, a row trigger is not run.
BEFORE and AFTER Triggers
When defining a trigger, you can specify the trigger timing--whether the trigger action is to be run before or after the triggering statement. BEFORE and AFTER apply to both statement and row triggers.
BEFORE and AFTER triggers fired by DML statements can be defined only on tables, not on views.
Difference between Trigger and Procedure
TriggersStored Procedures
In trigger no need to execute manually. Triggers will be fired automatically.
Triggers that run implicitly when an INSERT, UPDATE, or DELETE statement is issued against the associated table.Where as in procedure we need to execute manually.
Differences between stored procedure and functions
Stored ProcedureFunctions
Stored procedure may or may not return values.Function should return at least one output parameter. Can return more than one parameter using OUT argument.
Stored procedure can be used to solve the business logic.Function can be used to calculations
Stored procedure is a pre-compiled statement.But function is not a pre-compiled statement.
Stored procedure accepts more than one argument.Whereas function does not accept arguments.
Stored procedures are mainly used to process the tasks.Functions are mainly used to compute values
Cannot be invoked from SQL statements. E.g. SELECTCan be invoked form SQL statements e.g. SELECT
Can affect the state of database using commit.Cannot affect the state of database.
Stored as a pseudo-code in database i.e. compiled form.Parsed and compiled at runtime.
Data files Overview:A tablespace in an Oracle database consists of one or more physical datafiles. A datafile can be associated with only one tablespace and only one database.
Table Space:
Oracle stores data logically in tablespaces and physically in datafiles associated with the corresponding tablespace.
A database is divided into one or more logical storage units called tablespaces. Tablespaces are divided into logical units of storage called segments.
Control File:
A control file contains information about the associated database that is required for access by an instance, both at startup and during normal operation. Control file information can be modified only by Oracle; no database administrator or user can edit a control file.2.2 IMPORTANT QUERIES1. Get duplicate rows from the table:
Select empno, count (*) from EMP group by empno having count (*)>1;
2. Remove duplicates in the table:
Delete from EMP where rowid not in (select max (rowid) from EMP group by empno);
3. Below query transpose columns into rows.
NameNoAdd1Add2
abc100hydbang
xyz200Mysorepune
Select name, no, add1 from A
UNION
Select name, no, add2 from A;
4. Below query transpose rows into columns.
select
emp_id,
max(decode(row_id,0,address))as address1,
max(decode(row_id,1,address)) as address2,
max(decode(row_id,2,address)) as address3
from (select emp_id,address,mod(rownum,3) row_id from temp order by emp_id )
group by emp_id
Other query:
select
emp_id,
max(decode(rank_id,1,address)) as add1,
max(decode(rank_id,2,address)) as add2,
max(decode(rank_id,3,address))as add3
from
(select emp_id,address,rank() over (partition by emp_id order by emp_id,address )rank_id from temp )
group by
emp_id
5. Rank query:
Select empno, ename, sal, r from (select empno, ename, sal, rank () over (order by sal desc) r from EMP);
6. Dense rank query:
The DENSE_RANK function works acts like the RANK function except that it assigns consecutive ranks:
Select empno, ename, Sal, from (select empno, ename, sal, dense_rank () over (order by sal desc) r from emp);
7. Top 5 salaries by using rank:
Select empno, ename, sal,r from (select empno,ename,sal,dense_rank() over (order by sal desc) r from emp) where r=$$Pre_sess_max_upd (Mapping var)
3) In the expression assign max last_upd_date value to $$Pre_sess_max_upd(mapping var) using set max var
4) Because its var so it stores the max last upd_date value in the repository, in the next run our source qualifier query will fetch only the records updated or inseted after previous run.
Approach_2: Using parameter file
1 First need to create mapping parameter ($$Pre_sess_start_tmst )and assign initial value as old date (01/01/1940) in the parameterfile.
2 Then override source qualifier query to fetch only LAT_UPD_DATE >=$$Pre_sess_start_tmst (Mapping var)
3 Update mapping parameter($$Pre_sess_start_tmst) values in the parameter file using shell script or another mapping after first session get completed successfully
4 Because its mapping parameter so every time we need to update the value in the parameter file after comptetion of main session.
Approach_3: Using oracle Control tables
1 First we need to create two control tables cont_tbl_1 and cont_tbl_1 with structure of session_st_time,wf_name
2 Then insert one record in each table with session_st_time=1/1/1940 and workflow_name
3 create two store procedures one for update cont_tbl_1 with session st_time, set property of store procedure type as Source_pre_load .
4 In 2nd store procedure set property of store procedure type as Target _Post_load.this proc will update the session _st_time in Cont_tbl_2 from cnt_tbl_1.
5 Then override source qualifier query to fetch only LAT_UPD_DATE >=(Select session_st_time from cont_tbl_2 where workflow name=Actual work flow name.
SCD Type-II Effective-Date Approach
We have one of the dimension in current project called resource dimension. Here we are maintaining the history to keep track of SCD changes.
To maintain the history in slowly changing dimension or resource dimension. We followed SCD Type-II Effective-Date approach.
My resource dimension structure would be eff-start-date, eff-end-date, s.k and source columns.
Whenever I do a insert into dimension I would populate eff-start-date with sysdate, eff-end-date with future date and s.k as a sequence number.
If the record already present in my dimension but there is change in the source data. In that case what I need to do is
Update the previous record eff-end-date with sysdate and insert as a new record with source data.
Informatica design to implement SDC Type-II effective-date approach
Once you fetch the record from source qualifier. We will send it to lookup to find out whether the record is present in the target or not based on source primary key column.
Once we find the match in the lookup we are taking SCD column from lookup and source columns from SQ to expression transformation.
In lookup transformation we need to override the lookup override query to fetch Active records from the dimension while building the cache.
In expression transformation I can compare source with lookup return data.
If the source and target data is same then I can make a flag as S.
If the source and target data is different then I can make a flag as U.
If source data does not exists in the target that means lookup returns null value. I can flag it as I.
Based on the flag values in router I can route the data into insert and update flow.
If flag=I or U I will pass it to insert flow.
If flag=U I will pass this record to eff-date update flow
When we do insert we are passing the sequence value to s.k.
Whenever we do update we are updating the eff-end-date column based on lookup return s.k value.
Complex Mapping
We have one of the order file requirement. Requirement is every day in source system they will place filename with timestamp in informatica server.
We have to process the same date file through informatica.
Source file directory contain older than 30 days files with timestamps.
For this requirement if I hardcode the timestamp for source file name it will process the same file every day.
So what I did here is I created $InputFilename for source file name.
Then I am going to use the parameter file to supply the values to session variables ($InputFilename).
To update this parameter file I have created one more mapping.
This mapping will update the parameter file with appended timestamp to file name.
I make sure to run this parameter file update mapping before my actual mapping.
How to handle errors in informatica?
We have one of the source with numerator and denominator values we need to calculate num/deno
When populating to target.
If deno=0 I should not load this record into target table.
We need to send those records to flat file after completion of 1st session run. Shell script will check the file size.
If the file size is greater than zero then it will send email notification to source system POC (point of contact) along with deno zero record file and appropriate email subject and body.
If file size=($$INCREMENT_TS (Mapping var)
3) In the expression assign max last_upd_date value to ($$INCREMENT_TS (mapping var) using set max var
4) Because its var so it stores the max last upd_date value in the repository, in the next run our source qualifier query will fetch only the records updated or inseted after previous run.
Logic in the mapping variable is
Logic in the SQ is
In expression assign max last update date value to the variable using function set max variable.
Logic in the update strategy is below
Approach_2: Using parameter file
First need to create mapping parameter ($$LastUpdateDate Time )and assign initial value as old date (01/01/1940) in the parameterfile.
Then override source qualifier query to fetch only LAT_UPD_DATE >=($$LastUpdateDate Time (Mapping var)
Update mapping parameter($$LastUpdateDate Time) values in the parameter file using shell script or another mapping after first session get completed successfully
Because its mapping parameter so every time we need to update the value in the parameter file after comptetion of main session.
Parameterfile:[GEHC_APO_DEV.WF:w_GEHC_APO_WEEKLY_HIST_LOAD.WT:wl_GEHC_APO_WEEKLY_HIST_BAAN.ST:s_m_GEHC_APO_BAAN_SALES_HIST_AUSTRI]
$DBConnection_Source=DMD2_GEMS_ETL
$DBConnection_Target=DMD2_GEMS_ETL
$$LastUpdateDate Time =01/01/1940
Updating parameter File
Logic in the expression
Main mapping
Sql override in SQ Transformation
Workflod Design
4.2 Informatica Scenarios:
1) How to populate 1st record to 1st target ,2nd record to 2nd target ,3rd record to 3rd target and 4th record to 1st target through informatica?
We can do using sequence generator by setting end value=3 and enable cycle option.then in the router take 3 goups
In 1st group specify condition as seq next value=1 pass those records to 1st target simillarly
In 2nd group specify condition as seq next value=2 pass those records to 2nd target
In 3rd group specify condition as seq next value=3 pass those records to 3rd target.
Since we have enabled cycle option after reaching end value sequence generator will start from 1,for the 4th record seq.next value is 1 so it will go to 1st target.
2) How to do Dymanic File generation in Informatica?
I want to generate the separate file for every State (as per state, it should generate file).It has to generate 2 flat files and name of the flat file is corresponding state name that is the requirement.
Below is my mapping.
Source (Table) -> SQ -> Target (FF)
Source:
StateTransactionCity
AP2HYD
AP1TPT
KA5BANG
KA7MYSORE
KA3HUBLI
This functionality was added in informatica 8.5 onwards earlier versions it was not there.
We can achieve it with use of transaction control and special "FileName" port in the target file .
In order to generate the target file names from the mapping, we should make use of the special "FileName" port in the target file. You can't create this special port from the usual New port button. There is a special button with label "F" on it to the right most corner of the target flat file when viewed in "Target Designer".
When you have different sets of input data with different target files created, use the same instance, but with a Transaction Control transformation which defines the boundary for the source sets.
in target flat file there is option in column tab i.e filename as column.when you click that one non editable column gets created in metadata of target.
in transaction control give condition as iif(flag=1,tc_commit_before,tc_continue_tranaction)
map the state column to target's filename column
ur mapping will be like this
source -> sq->expression-> transaction control-> target
run it ,separate files will be created by name of state3) How to concatenate row data through informatica?
Source:
EnameEmpNo
stev100
methew100
john101
tom101
Target:
EnameEmpNo
Stev methew100
John tom101
Approach1: Using Dynamic Lookup on Target table:
If record doent exit do insert in target .If it is already exist then get corresponding Ename vale from lookup and concat in expression with current Ename value then update the target Ename column using update strategy.
Approch2: Using Var port :
Sort the data in sq based on EmpNo column then Use expression to store previous record information using Var port after that use router to insert a record if it is first time if it is already inserted then update Ename with concat value of prev name and current name value then update in target.
4) How to send Unique (Distinct) records into One target and duplicates into another tatget?
Source:
EnameEmpNo
stev100
Stev100
john101
Mathew102
Output:
Target_1:
EnameEmpNo
Stev 100
John 101
Mathew102
Target_2:
EnameEmpNo
Stev 100
Approch 1: Using Dynamic Lookup on Target table:
If record doent exit do insert in target_1 .If it is already exist then send it to Target_2 using Router.
Approch2: Using Var port :
Sort the data in sq based on EmpNo column then Use expression to store previous record information using Var ports after that use router to route the data into targets if it is first time then sent it to first target if it is already inserted then send it to Tartget_2.
5) How to Process multiple flat files to single target table through informatica if all files are same structure?
We can process all flat files through one mapping and one session using list file.
First we need to create list file using unix script for all flat file the extension of the list file is .LST.
This list file it will have only flat file names.
At session level we need to set
source file directory as list file pathAnd source file name as list file nameAnd file type as indirect.
6) How to populate file name to target while loading multiple files using list file concept.
In informatica 8.6 by selecting Add currently processed flatfile name option in the properties tab of source definition after import source file defination in source analyzer.It will add new column as currently processed file name.we can map this column to target to populate filename.
7) If we want to run 2 workflow one after another(how to set the dependence between wfs)
If both workflow exists in same folder we can create 2 worklet rather than creating 2 workfolws.
Finally we can call these 2 worklets in one workflow.
There we can set the dependency.
If both workflows exists in different folders or repository then we cannot create worklet.
We can set the dependency between these two workflow using shell script is one approach.
The other approach is event wait and event rise.
If both workflow exists in different folrder or different rep then we can use below approaches.
1) Using shell script
As soon as first workflow get completes we are creating zero byte file (indicator file).
If indicator file is available in particular location. We will run second workflow.
If indicator file is not available we will wait for 5 minutes and again we will check for the indicator. Like this we will continue the loop for 5 times i.e 30 minutes.
After 30 minutes if the file does not exists we will send out email notification.
2) Event wait and Event rise approach
We can put event wait before actual session run in the workflow to wait a indicator file if file available then it will run the session other event wait it will wait for infinite time till the indicator file is available.
8) How to load cumulative salary in to target ?Solution:
Using var ports in expression we can load cumulative salary into target.
4.3 Development Guidelines
General Development Guidelines
The starting point of the development is the logical model created by the Data Architect. This logical model forms the foundation for metadata, which will be continuously be maintained throughout the Data Warehouse Development Life Cycle (DWDLC). The logical model is formed from the requirements of the project. At the completion of the logical model technical documentation defining the sources, targets, requisite business rule transformations, mappings and filters. This documentation serves as the basis for the creation of the Extraction, Transformation and Loading tools to actually manipulate the data from the applications sources into the Data Warehouse/Data Mart.
To start development on any data mart you should have the following things set up by the Informatica Load Administrator
Informatica Folder. The development team in consultation with the BI Support Group can decide a three-letter code for the project, which would be used to create the informatica folder as well as Unix directory structure.
Informatica Userids for the developers
Unix directory structure for the data mart.
A schema XXXLOAD on DWDEV database.
Transformation Specifications
Before developing the mappings you need to prepare the specifications document for the mappings you need to develop. A good template is placed in the templates folder You can use your own template as long as it has as much detail or more than that which is in this template.
While estimating the time required to develop mappings the thumb rule is as follows.
Simple Mapping 1 Person Day
Medium Complexity Mapping 3 Person Days
Complex Mapping 5 Person Days.
Usually the mapping for the fact table is most complex and should be allotted as much time for development as possible.
Data Loading from Flat Files
Its an accepted best practice to always load a flat file into a staging table before any transformations are done on the data in the flat file.
Always use LTRIM, RTRIM functions on string columns before loading data into a stage table.
You can also use UPPER function on string columns but before using it you need to ensure that the data is not case sensitive (e.g. ABC is different from Abc)
If you are loading data from a delimited file then make sure the delimiter is not a character which could appear in the data itself. Avoid using comma-separated files. Tilde (~) is a good delimiter to use.
Failure Notification
Once in production your sessions and batches need to send out notification when then fail to the Support team. You can do this by configuring email task in the session level.
Naming Conventions and usage of Transformations
Port Standards:
Input Ports It will be necessary to change the name of input ports for lookups, expression and filters where ports might have the same name. If ports do have the same name then will be defaulted to having a number after the name. Change this default to a prefix of in_. This will allow you to keep track of input ports through out your mappings.Prefixed with: IN_Variable Ports Variable ports that are created within an expression
Transformation should be prefixed with a v_. This will allow the developer to distinguish between input/output and variable ports. For more explanation of Variable Ports see the section VARIABLES.Prefixed with: V_Output Ports If organic data is created with a transformation that will be mapped to the target, make sure that it has the same name as the target port that it will be mapped to.
Prefixed with: O_Quick Reference
Object TypeSyntax
FolderXXX_
Mappingm_fXY_ZZZ__x.x
Sessions_fXY_ZZZ__x.x
Batchb_
Source Definition
Target Definition
AggregatorAGG_
ExpressionEXP_
FilterFLT_
JoinerJNR_
LookupLKP_
NormalizerNorm_
RankRNK_
RouterRTR_
Sequence GeneratorSEQ_
Source QualifierSQ_
Stored ProcedureSTP__
Update StrategyUPD__xxx
MappletMPP_
Input TransformationINP_
Output TranformationOUT_
Database ConnectionsXXX__
4.4 Performance Tips
What is Performance tuning in InformaticaThe aim of performance tuning is optimize session
performance so sessions run during the available load window
for the Informatica Server.
Increase the session performance by following.
The performance of the Informatica Server is related to
network connections. Data generally moves across a network
at less than 1 MB per second, whereas a local disk moves
data five to twenty times faster. Thus network connections
ofteny affect on session performance. So avoid work
connections.
1. Cache lookups if source table is under 500,000 rows and DONT cache for tables over 500,000 rows.
2. Reduce the number of transformations. Dont use an Expression Transformation to collect fields. Dont use an Update Transformation if only inserting. Insert mode is the default.
3. If a value is used in multiple ports, calculate the value once (in a variable) and reuse the result instead of recalculating it for multiple ports.
4. Reuse objects where possible.
5. Delete unused ports particularly in the Source Qualifier and Lookups.
6. Use Operators in expressions over the use of functions.
7. Avoid using Stored Procedures, and call them only once during the mapping if possible.
8. Remember to turn off Verbose logging after you have finished debugging.
9. Use default values where possible instead of using IIF (ISNULL(X),,) in Expression port.
10. When overriding the Lookup SQL, always ensure to put a valid Order By statement in the SQL. This will cause the database to perform the order rather than Informatica Server while building the Cache.
11. Improve session performance by using sorted data with the Joiner transformation. When the Joiner transformation is configured to use sorted data, the Informatica Server improves performance by minimizing disk input and output.
12. Improve session performance by using sorted input with the Aggregator Transformation since it reduces the amount of data cached during the session.
13. Improve session performance by using limited number of connected input/output or output ports to reduce the amount of data the Aggregator transformation stores in the data cache.
14. Use a Filter transformation prior to Aggregator transformation to reduce unnecessary aggregation.
15. Performing a join in a database is faster than performing join in the session. Also use the Source Qualifier to perform the join.
16. Define the source with less number of rows and master source in Joiner Transformations, since this reduces the search time and also the cache.
17. When using multiple conditions in a lookup conditions, specify the conditions with the equality operator first.
18. Improve session performance by caching small lookup tables.
19. If the lookup table is on the same database as the source table, instead of using a Lookup transformation, join the tables in the Source Qualifier Transformation itself if possible.
20. If the lookup table does not change between sessions, configure the Lookup transformation to use a persistent lookup cache. The Informatica Server saves and reuses cache files from session to session, eliminating the time required to read the lookup table.
21. Use :LKP reference qualifier in expressions only when calling unconnected Lookup Transformations.
22. Informatica Server generates an ORDER BY statement for a cached lookup that contains all lookup ports. By providing an override ORDER BY clause with fewer columns, session performance can be improved.
23. Eliminate unnecessary data type conversions from mappings.
24. Reduce the number of rows being cached by using the Lookup SQL Override option to add a WHERE clause to the default SQL statement.
4.5 Unit Test Cases (UTP):
QA Life Cycle consists of 5 types of
Testing regimens:
1. Unit Testing
2. Functional Testing
3. System Integration Testing
4. User Acceptance Testing
Unit testing: The testing, by development, of the application modules to verify each unit (module) itself meets the accepted user requirements and design and development standards
Functional Testing: The testing of all the applications modules individually to ensure the modules, as released from development to QA, work together as designed and meet the accepted user requirements and system standards
System Integration Testing: Testing of all of the application modules in the same environment, database instance, network and inter-related applications, as it would function in production. This includes security, volume and stress testing.
User Acceptance Testing(UAT): The testing of the entire application by the end-users ensuring the application functions as set forth in the system requirements documents and that the system meets the business needs.UTP Template:
Step
#DescriptionTest ConditionsExpected ResultsActual Results, Pass or Fail
(P or F)Tested By
SAP- CMS Interfaces
1Check for the total count of records in source tables that is fetched and the total records in the PRCHG table for a perticular session timestamp
SOURCE:
SELECT count(*) FROM XST_PRCHG_STG
TARGET:
Select count(*) from _PRCHG Both the source and target table load record count should match.
Should be same as the expected
PassStev
2Check for all the target columns whether they are getting populated correctly with source data.
select PRCHG_ID,
PRCHG_DESC,
DEPT_NBR,
EVNT_CTG_CDE,
PRCHG_TYP_CDE,
PRCHG_ST_CDE,
from T_PRCHG
MINUS
select PRCHG_ID,
PRCHG_DESC,
DEPT_NBR,
EVNT_CTG_CDE,
PRCHG_TYP_CDE,
PRCHG_ST_CDE,
from PRCHGBoth the source and target table record values should return zero records
Should be same as the expected
PassStev
3Check for Insert strategy to load records into target table.
Identify a one record from the source which is not in target table. Then run the sessionIt should insert a record into target table with source dataShould be same as the expected
PassStev
4Check for Update strategy to load records into target table.
Identify a one Record from the source which is already present in the target table with different PRCHG_ST_CDE or PRCHG_TYP_CDE values Then run the sessionIt should update record into target table with source data for that existing record
Should be same as the expected
PassStev
5 UNIX
How strong you are in UNIX?
1) I have Unix shell scripting knowledge whatever informatica required like
If we want to run workflows in Unix using PMCMD.
Below is the script to run workflow using Unix.
cd /pmar/informatica/pc/pmserver/
/pmar/informatica/pc/pmserver/pmcmd startworkflow -u $INFA_USER -p $INFA_PASSWD -s $INFA_SERVER:$INFA_PORT -f $INFA_FOLDER -wait $1 >> $LOG_PATH/$LOG_FILE
2) And if we suppose to process flat files using informatica but those files were exists in remote server then we have to write script to get ftp into informatica server before start process those files.
3) And also file watch mean that if indicator file available in the specified location then we need to start our informatica jobs otherwise will send email notification using
Mail X command saying that previous jobs didnt completed successfully something like that.
4) Using shell script update parameter file with session start time and end time.
This kind of scripting knowledge I do have. If any new UNIX requirement comes then I can Google and get the solution implement the same.
Basic Commands:
Cat file1 (cat is the command to create none zero byte file)cat file1 file2 > all -----it will combined (it will create file if it doesnt exit)cat file1 >> file2---it will append to file 2
> will redirect output from standard out (screen) to file or printer or whatever you like.
>> Filename will append at the end of a file called filename.
< will redirect input to a process or command.
How to create zero byte file?Touch filename (touch is the command to create zero byte file)
how to find all processes that are running
ps -A
Crontab command. Crontab command is used to schedule jobs. You must have permission to run this command by Unix Administrator. Jobs are scheduled in five numbers, as follows.
Minutes (0-59) Hour (0-23) Day of month (1-31) month(1-12) Day of week (0-6) (0 is Sunday)
so for example you want to schedule a job which runs from script named backup jobs in /usr/local/bin directory on sunday (day 0) at 11.25 (22:25) on 15th of month. The entry in crontab file will be. * represents all values.
25 22 15 * 0 /usr/local/bin/backup_jobs
The * here tells system to run this each month. Syntax is crontab file So a create a file with the scheduled jobs as above and then typecrontab filename .This will scheduled the jobs.
Below cmd gives total no of users logged in at this time.
who | wc -l
echo "are total number of people logged in at this time."
Below cmd will display only directories
$ ls -l | grep '^d'
Pipes:
The pipe symbol "|" is used to direct the output of one command to the input
of another.
Moving, renaming, and copying files:
Cp file1 file2 copy a file
mv file1 newname move or rename a file
mv file1 ~/AAA/ move file1 into sub-directory AAA in your home directory.
rm file1 [file2 ...] remove or delete a file
To display hidden files
ls a
Viewing and editing files:cat filename Dump a file to the screen in ascii.
More file name to view the file content
head filename Show the first few lines of a file.
head -5 filename Show the first 5 lines of a file.
tail filename Show the last few lines of a file.
Tail -7 filename Show the last 7 lines of a file.
Searching for files :
find commandfind -name aaa.txt Finds all the files named aaa.txt in the current directory or
any subdirectory tree.
Sed (The usual sed command for global string search and replace is this)
If you want to replace 'foo' with the string 'bar' globally in a file.$ sed -e 's/foo/bar/g' myfile.txt
find / -name vimrc Find all the files named 'vimrc' anywhere on the system.
find /usr/local/games -name "*xpilot*"
Find all files whose names contain the string 'xpilot' which
exist within the '/usr/local/games' directory tree.
You can find out what shell you are using by the command:
echo $SHELL
If file exists then send email with attachment.
if [[ -f $your_file ]]; thenuuencode $your_file $your_file|mailx -s "$your_file exists..." your_email_addressfi
Below line is the first line of the script
#!/usr/bin/sh
Or
#!/bin/ksh
What does #! /bin/sh mean in a shell script?
It actually tells the script to which interpreter to refer. As you know, bash shell has some specific functions that other shell does not have and vice-versa. Same way is for perl, python and other languages.It's to tell your shell what shell to you in executing the following statements in your shell script.
Interactive HistoryA feature of bash and tcsh (and sometimes others) you can use
the up-arrow keys to access your previous commands, edit
them, and re-execute them.
Basics of the vi editor Opening a file
Vi filename
Creating text
Edit modes: These keys enter editing modes and type in the text
of your document.
i Insert before current cursor position
I Insert at beginning of current line
a Insert (append) after current cursor position
A Append to end of line
r Replace 1 character
R Replace mode
Terminate insertion or overwrite mode
Deletion of text
x Delete single character
dd Delete current line and put in buffer
:w Write the current file.
:w new.file Write the file to the name 'new.file'.
:w! existing.file Overwrite an existing file with the file currently being edited.
:wq Write the file and quit.
:q Quit.
:q! Quit with no changes. Page 50 of 99DWH Training -9739096158