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What is Join index
Hi everyone ,Can u explain in detail what is a join index,with example.And what is its importance in teradata.
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rin23- Member Since May-2011 | May 12th, 2011
A join Index is a cross between a view and an index. It is like a view in that it is created using a query to specify the structure, composition and source of the contents. It is like an index in the way that it is used automatically by the database system to improve the performance of a query. Join indexes use the "classic" space-time trade off trading disk space for storage of the join index to get improved performance for queries. Unlike many other materialized view implementations, Teradata join indexes are updated immediately and automatically when changes are made to the base tables. There is never a concern that you might be using stale data when the system chooses to use a join index in the query plan. Also, Teradata uses its sophisticated coverage testing algorithm to minimize the cost associated with join index maintenance.?
rin23
- May 12th, 2011
A join Index is a cross between a view and an index. It is like a view in that it is created using a query to specify the structure, composition and source of the contents. It is like an index in the ...
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Informatica
I have 2 sources one is relational table with 7 ports
second is flat file with 8 ports.How can I get the combined output and I should not do any modifications to the source structure?priyank_divya
- Aug 3rd, 2012
Hi, I think we can obtain the results by using Joiner transformation. If the sources have no common columns, we can add one extra column with a value 1 in both the sources and then can join based on ...
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How to explain sales project in interview.
How to explain sales project in interview.could u tell me modules or dim table with some column names and facts how to move data from dim to facts.and give me what logic u implement in that projects
Lokesh M
- Jan 3rd, 2013
For explaining your sales project: You can follow these points and cover them based on your actual project. 1. Name of the Project 2. Name of the Client 3. Brief Description of the Client 4. Brief ...
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What are various types of Aggregation?
Various types of aggregation are SUM, AVG, COUNT, MAX, MIN, FIRST, LAST, MEDIAN, PERCENTILE, STDDEV, and VARIANCE.
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sithusithu
- Jan 19th, 2006
AVG COUNT FIRST LAST MAX MEDIAN MIN PERCENTILE STDDEV SUM VARIANCECheers,Sithu
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What is Load Manager?
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Answered by: Deb
- Jun 8th, 2005
I am providing the answer which I have taken it from Informatica 7.1.1 manual,
Ans: While running a Workflow,the PowerCenter Server uses the Load Manager process and the Data Transformation Manager Process (DTM) to run the workflow and carry out workflow tasks.When the PowerCenter Server runs a workflow, the Load Manager performs the following tasks:
1. Locks the workflow and reads workflow properties.
2. Reads the parameter file and expands workflow variables.
3. Creates the workflow log file.
4. Runs workflow tasks.
5. Distributes sessions to worker servers.
6. Starts the DTM to run sessions.
7. Runs sessions from master servers.
8. Sends post-session email if the DTM terminates abnormally.
When the PowerCenter Server runs a session, the DTM performs the following tasks:
1. Fetches session and mapping metadata from the repository.
2. Creates and expands session variables.
3. Creates the session log file.
4. Validates session code pages if data code page validation is enabled. Checks query
conversions if data code page validation is disabled.
5. Verifies connection object permissions.
6. Runs pre-session shell commands.
7. Runs pre-session stored procedures and SQL.
8. Creates and runs mapping, reader, writer, and transformation threads to extract,transform, and load data.
9. Runs post-session stored procedures and SQL.
10. Runs post-session shell commands.
11. Sends post-session email.raju4dw
- Aug 6th, 2010
Load Manager is responsible for dispatching the sessions and maintains Q of sessions based on first in and first out. Load Manager is also known as Master Processor (DTM) Data Transformation Manager.D...
Deb
- Jun 8th, 2005
I am providing the answer which I have taken it from Informatica 7.1.1 manual, Ans: While running a Workflow,the PowerCenter Server uses the Load Manager process and the Data Transformation...
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How many ways you can update a relational source definition ?
Two ways 1. Edit the definition 2. Reimport the defintion
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Sumithav29- Member Since Jun-2009 | Jun 12th, 2009
1. If you want to make minor changes to the source definition, you can edit the source definition (in source analyzer) then the Designer propagates the changes to all mappings using that source.
2. If the source changes are significant, re-import the source and giving replace option while re-importing will reflect the changes in all the mappings where the source is used.Sumithav29
- Jun 12th, 2009
1. If you want to make minor changes to the source definition, you can edit the source definition (in source analyzer) then the Designer propagates the changes to all mappings using that source.2. If ...
gazulas
- Jan 30th, 2006
in 2 ways we can do it 1) by reimport the source definition 2) by edit the source definition
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Which transformation you need while using the COBOL sources as source definitions?
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sithusithu- Member Since Dec-2005 | Jan 20th, 2006
Normalizer transformation.
Normalizer transformation which is used to normalize the data.Since COBOL sources are often consists of De-normalized data.sithusithu
- Jan 20th, 2006
Normalizer transformation. Normalizer transformation which is used to normalize the data.Since COBOL sources are often consists of De-normalized data.
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What is staging are why we need it
Mahendra Rajpoot
- Sep 17th, 2014
Staging area may be required if you have any of the following scenarios: Delta Loading: Your data is read incrementally from the source and you need an intermediate storage where incremental set of y...
MAHESH MANAM
- Aug 16th, 2012
It is a automated process of building a data warehouse which involves taking the data from disparate source systems, converting them into a consistent form that can be loaded into the warehouse and pe...
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Which source definition files are needed to provide support for Mainframes ?
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deepthi_97- Member Since Sep-2009 | Sep 23rd, 2009
Cobol files and we use normalizer transformation
Prabu
- Jun 22nd, 2007
The mainframe files are Used as VSAM files in Informatica by using the Normaliser transformation
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What is granularity in INFORMATICA? How should be the level of granularity for a fact table as well as for a dimension table?
P.Sivakumar
- Sep 12th, 2007
Granularity is a lowest level of information stored in databse that is called as granularity.
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Discuss the advantages & Disadvantages of star & snowflake schema?
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Answered by: swati
- Nov 5th, 2005
star schema consists of single fact table surrounded by some dimensional table.In snowflake schema the dimension tables are connected with some subdimension table.
In starflake dimensional ables r denormalized,in snowflake dimension tables r normalized.
star schema is used for report generation ,snowflake schema is used for cube.
The advantage of snowflake schema is that the normalized tables r easier to maintain.it also saves the storage space.
The disadvantage of snowflake schema is that it reduces the effectiveness of navigation across the tables due to large no of joins between them.
halgai
- Oct 8th, 2007
Snowflakes are an addition to the Kimball Dimensional system to enable that system to handle hierarchial data. When Kimball proposed the dimensional data warehouse it was not first recogonized t...
Richard
- Feb 2nd, 2006
It depends upon the clients which they are following, whether snowflake or star schema.
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What are the meta data of source you import while importing the relational source definition from database ?
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Answered by: srinvas vadlakonda
- Sep 28th, 2006
Source name
Database location
Column names
Datatypes
Key constraints
srikanth
- May 11th, 2022
Column names
Sumithav29
- Jun 12th, 2009
ODBC data source, username, owner name, password. Once the connection is established, select the table.
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What is the difference between Narmal load and Bulk load?
hanimi
- Apr 28th, 2011
Bulk load the dwh server bypass the data to the target, in that we have session performance improves.in normal load data moves the database log file.
Ray
- Mar 22nd, 2006
Also remember that not all databases support bulk loading. and bulk loading fails a session if your mapping has primary keys
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What is Data Transformation Manager?
After the load manager performs validations for the session, it creates the DTM process. The DTM process is the second process associated with the session run. The primary purpose of the DTM process is to create and manage threads that carry out the session tasks.· The DTM allocates process memory for the session and divide it into buffers. This is also known as buffer memory. It creates the main thread,...
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Goush- Member Since May-2007 | May 15th, 2007
When the workflow reaches a session, the Integration Service process starts
the DTM process. The DTM is the process associated with the session and it
performs the following tasks:
1. Retrieves and validates session information from the repository.
2. Performs pushdown optimization when the session is configured for
pushdown optimization.
3. Adds partitions to the session when the session is configured for dynamic
partitioning.
4. Forms partition groups when the session is configured to run on a grid.
5. Expands the service process variables, session, and mapping variables and
parameters.
6. Creates the session log.
7. Validates source and target code pages.
8. Verifies connection object permissions.
9. Runs pre-session shell commands, stored procedures and SQL.
10. Sends a request to start worker DTM processes on other nodes when the
session is configured to run on a grid.
11. Creates and runs mapping, reader, writer, and transformation threads to
extract, transform, and load data.
12. Runs post-session stored procedures, SQL, and shell commands
13. Sends post-session email.
jayapraveen
- Oct 4th, 2010
load manager creates the DTM(data transformation manager)in the work flow manager by the informatica server ,here DTM creates two threads 1.reader thread2.writer threadDTM reads the data from &nb...
chandrarekha
- Sep 6th, 2007
Load manager and DTM are the components of Informatica server. Load manager manages the load on the server by maintaining a queue of sessions and release the session based on first come and firs...
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What r the join types in joiner transformation?
Normal (Default) Master outer Detail outer Full outer
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How can I use multiple filter transformations? How do I pass dropped rows to next filter transformation to check the conditions?
Rajarao marisa
- May 31st, 2012
Ok its not good work environment by using multiple filter t/r usage Any way by using multiple filter we can load rejected rows also SD-->SQ-->fltr(condition(true)(eg:deptno=10)---->loaded into one tar...
srinuraj
- May 31st, 2010
You can use filter transformations to filter rows. Filter transformations passes rows to next transformation which rows met the condition. But it cannot pass rows which rows doesn't meet the condition...
Informatica Interview Questions
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