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Adabas Training
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Course Scope
Strengths of Adabas Inside Adabas Using Adabas Conclusion
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ADABAS - Strengths
Compression of DATA Performance Fault Tolerance High Availability
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ADABAS - Strengths
Compression of DATA– Why Data is compressed?
Saves lot of SpaceMany ADABAS files require only 50% to 60% of the space used for the raw data.Even with the addition of approximately 25% for the access structures stored in the Associator, ADABAS storage requirements are still less than those required for other DBMS
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ADABAS - Strengths
Compression of DATA– ADABAS records are internally stored in
compressed format.– ADABAS defines and executes compression at
field level.– During retrieval of data, ADABAS decompresses
the data.
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ADABAS - Strengths
Compression of DATAThere are 3 TYPES of compression1. Default Compression( also called Normal
Compression)
2. Null Suppression
3. Fixed Format
We can choose the type of compression for a field by setting the compression option in the file definition.
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ADABAS - Strengths
Compression of DATA
DB 252 File 3 - AUTOMOBILEST L DB Name F Leng S D Remarks- - ------------------------------ - ---- - - ----------- 1 AA COLOR A 3 N D 1 AB MAKE A 20 N D 1 AC MODEL A 20 N 1 AD LICENSE A 15 N 1 BA YEAR N 4.0 N 1 BB HORSEPOWER N 3.0 N 1 BC PRICE N 5.0 N 1 BD RECALLS N 5.0 N 1 S1 SP-MAKE-MODEL A 40 N S
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ADABAS - Strengths
Compression of DATA1. Default Compression:
Compresses the trailing blanks and leading zeroes.
An empty field is replaced by one-byte Empty Field Counter (EFC)
At the beginning of each field there is an one-byte field called Inclusive Length Byte (ILB) which stores the length of each fields (including one byte for ILB)
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ADABAS - Strengths
Compression of DATA– Example for Default Compression
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ADABAS - Strengths
Compression of DATA 2. Null Suppression : similar to Default Suppression BUT doesn’t allow zeros or blanks for Descriptor
defined with Null Suppression3. Fixed Format: no compression at all Doesn’t need one byte length indicator (ILB) Mostly used for one-byte fields.
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ADABAS - Strengths
Performance– Performance is the key factor of ADABAS, which
includes a number of features to enhance it.– For instance, a number of set-up parameters are
available for fine-tuning the database operating environment, and many of these can be modified while the database is active.
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ADABAS - Strengths
Fault Tolerance– ADABAS recovers automatically after an
abnormal database or system termination.– If a transaction was interrupted, ADABAS
automatically resets all changes of the uncompleted transaction so that the database is consistent.
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ADABAS - Strengths
High Availability– ADABAS is designed for operation 7 days a week
and 24 hours a day.– files can be loaded and unloaded, backed up and
restored, and system performance can be analyzed without interrupting the active database.
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Course Scope
Strengths of Adabas Inside Adabas Using Adabas Conclusion
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Inside ADABAS
ADABAS System
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Inside ADABAS
Overview of Adabas and Front-ends
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Inside ADABAS
Data Storage
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Inside ADABAS
Associators – Inverted List & Address converters
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Inside ADABAS
Adabas access technique
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Inside ADABAS
Example
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Inside ADABAS
Example
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Inside ADABAS
LogsPLOG – Protection Log
– records before- and after-images of records and other elements when changes are made to the database.
CLOG – Command Log– records each ADABAS command that is issued.
RLOG – Recovery Log– records additional info that the ADABAS Recovery Aid can
use for recovery
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Inside ADABAS
FDT – Field Definition Table
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Inside ADABAS
FDT Field options
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Inside ADABAS
ADABAS field types –> 4 field types
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Inside ADABAS
How ADABAS finds the data…
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Course Scope
Strengths of Adabas Inside AdabasUsing Adabas Conclusion
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Using ADABAS
READ Command FIND Command GET Command HISTOGRAM Command STORE UPDATE DELETE
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Using ADABAS
READ Command - 3 TYPES1. READ LOGICAL (READ BY)
2. READ BY ISN
3. READ PHYSICAL
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Using ADABAS
READ LOGICAL (READ BY) Following are the steps to process logical READ
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Using ADABAS
READ LOGICAL – Diagrammatic view
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Using ADABAS
READ BY ISN
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Using ADABAS
READ BY ISN - Diagrammatic View
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Using ADABAS
READ PHYSICAL
1. In Processing a physical READ, ADABAS goes directly to Data Storage and reads the records as they sit in the storage.
2. It does not goes thru an Inverted List
3. It does not goes thru the address converter
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Using ADABAS
READ PHYSICAL – Diagrammatic View
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Using ADABAS
FIND command1. When FIND command is issued, it first
builds an inverted list from the existing inverted list.
2. It stores the inverted list in the Work Area.3. From the newly built Inverted list, it
accesses the data storage thru the address converter.
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Using ADABAS
FIND command – Diagrammatic view
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Using ADABAS
GET command– Used to retrieve single record using the ISN.– But the Problem is that we have to know the ISN.– So Mostly we use GET when we need to access
a record which has been accessed shortly before.– So, When we access it for the first time, we store
the ISN. – Then when we need it again, we can use the ISN
and issue the GET command.
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Using ADABAS
GET command – Diagrammatic View
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Using ADABAS
HISTOGRAM Command
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Using ADABAS
HISTOGRAM Command
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Using ADABAS
HISTOGRAM – Diagrammatic View
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Using ADABAS
So far, we have seen ways to extract data from the ADABAS.
Now, we are going to see , how we are going to put data into the ADABAS.
For that, we use:1. STORE ( similar to INSERT in SQL)
2. UPDATE and
3. DELETE ( this one for removing data)
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Using ADABAS
STORE command
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Using ADABAS
UPDATE Command To update an Adabas record:
1. retrieve the Adabas record
2. ADABAS will “HOLD” the record, when it sees that we are retrieving for UPDATE
3. No other program can have access to the “HOLD” record, until it is released by the UPDATE.
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Using ADABAS
UPDATE Command
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Using ADABAS
DELETE Command
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Using ADABAS
DELETE Command - Example
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ADABAS to NATURAL Cross-reference
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ADABAS to NATURAL Cross-reference
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Course Scope
Strengths of Adabas Inside Adabas Using AdabasConclusion
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ADABAS - Q & A
Got any Questions?
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Helps Available
Following are the types of help available when are dealing with Natural-Adabas.
1. Issue HELP command on editor line
2. Issue ? on editor line
3. or mail me -> [email protected]
T H A N K Y O U !!!
