Strategies for Unlocking Knowledge Management in Microsoft 365 in the Copilot...
File Organization
1. FILES ORGANIZATION
PRESENTED BY :
KU MAN YI B031210161
MOHAMMAD SAFAR A/L SHARIFF MOHAMED B031210227
ADAM RIDHWAN BIN SUKIMAN B031210083
SOO BOON JIAN B031210199
MUHAMMAD ZULKHAIRI BIN ZAINI B031210140
3. THE PILE
A form of file organization where data are collected in
the same order they arrived
This organization simply accumulate mass of data and
save it
Each field is self-describing, includes a field name and a
value. Length of each field is determined as shown
Implicitly indicated by delimiters
Explicitly included as subfield or
Done by default for that particular field type
Records may have different fields and there is no visible
structure. Hence, record access is through exhaustive
search where all record or the entire file is examined
This type of file uses space efficiently and is updated
easily. However, retrieval of a single record could be
tedious
4. THE PILE ORGANIZATION
Variable-length records Delimiter
Delimiter
Delimiter
Delimiter
Delimiter
Delimiter
Variable-length records
Variable-length records
Variable-length records
Variable-length records
5. THE SEQUENTIAL FILE
Most common form of file structure
Fixed format are used for records and records are of the
same length
Field names and lengths are attributes of the file
One particular field (usually first field) is referred to as
the key field :-
Uniquely identifies the record
Records are stored in key sequence
Alphabetical order or numerical order depending on the key field
It is the simplest structure and easy to implement in any
device. However, in the worst case scenario, accessing
a single record takes a long time.
7. THE SEQUENTIAL FILE ORGANIZATION
To enable a sequential form of records, new
records are placed in a log file or transaction file.
Then, a batch update is performed to merge the log
file with the master file to produce a new file with
the correct key sequence
1 2 n-1 n
…
Record
Terminators
8. THE INDEXED SEQUENTIAL FILE
A file management system that allows records to be
accessed either sequentially (in the order they were
entered) or randomly (with an index)
A secondary set of hash tables known as indexes is
created that contains pointers to the main file
In indexed sequential file, records are organized in
sequence based on key fields
Each file has an index to support random search
Overflow file is added such as each record in
overflow file is located by following a pointer from
its predecessor record in main file
9. DESCRIPTION
As an example:-
Firstly, a single level of indexing is used. Hence, the
index is a simple sequential file.
Each record in the index file consists of:-
Key field(same as key field in the main file)
Pointer to the main file
To find a specific field, the index file is searched for
matching key values
Then, the pointer indicates the record having the
matching key values as depicted by figure below
This reduces the average search length
10.
11. There is an addition to the organization where each record in
the main file contains an additional field which is a pointer to
the overflow file
When a new record is added, it is added into the overflow file.
The record in main file which is immediately before the new
record in a logical sequence to be inserted is updated to
contain a pointer to the new record in the overflow file
However, if the record before the new record in logical
sequence is itself in the overflow file, then the pointer in that
record is updated
The processing of entire file sequentially involves processing
of records of main files sequentially until the pointer to the
overflow file is found, then accessing is continued in the
overflow file until a null pointer is encountered
Secondly, we visualize the organization using multiple levels
of indexes
The lowest level of index points to the main file, whereas the
index files sitting on the level above points to the index file
below it
Hence, the efficiency in access is greatly increased and
average length of search is greatly reduced as conveyed in
figure below
12.
13. THE INDEXED FILE
Uses multiple indexes for different key fields which
may be the subject of a search
Record accessibility are through their indexes
May contain an exhaustive index that contains one
entry for every record in the main file. The index
itself is organized in the sequential form for ease of
searching
May contain a partial index. It contains entries to
records where the desired field exists
14. THE INDEXED FILE ORGANIZATION
Primary file
Exhaustive PartialExhaustive
Index Attributes
Pointer
Indicator
15. THE DIRECT/HASHED FILE
This file management system that access directly any
block of a known address.
A key field is required for each record.
Uses hashing on the key value.
No concept of sequential ordering implemented.
Such examples are:-
Directories
Pricing table
Schedules
Name lists
It is used where rapid access is required, where fixed-
length records are used and where records are
accessed one-at-a-time.
The concept of hashing can be shown as below.
17. HASHING METHODS
Direct method
The key is the address
a key value might be between 1-100. The address of a certain
records will be the same as the key.
Subtraction method
Subtract certain amount of numbers from the key
a key value might start with 1001 and ends with 1100. A simple
hashing function could subtract 1000 from the key to determine
the address.
Modulo-division method
Key value is divided by the size of records.
the remainder becomes the address of the key.
Digit-extraction method
Selected digits are extracted from the key
As an example:- a field has 10 digits. The hashing function only
extracts the first 2 digits and the last digit and use them as
address.