Can anyone please tell me the exac difference between cardinality and uniqueness?
I'm doing column analysis in Information analyzer, for a column the percentage of Cardinality and Uniqueness is different, but as per the definition of cardinality it represent "uniquness".
Please help me out..
Difference between cardinality and uniqueness
Difference between cardinality and uniqueness
IBM Certified - Information Server 8.1
Think of cardinality as the count of distinct values within the column.
For a field like transaction date you would expect a low number of distinct values.
If you had the values:
01-01-2009
01-01-2009
02-01-2009
02-01-2009
03-01-2009
You would expect a value of 3.
For a field, which is a primary key, you would expect a high number of distinct values.
Uniqueness count is the count of unique values.
For a field like transaction date you would expect a low number. You wouldn't expect to find many dates, which have occurred once.
If you had the values:
01-01-2009
01-01-2009
02-01-2009
02-01-2009
03-01-2009
You would expect a uniqueness count of 1.
For a field that is a key you would expect a high number. The uniqueness count should be the same value as the total actual row count.
For a field like transaction date you would expect a low number of distinct values.
If you had the values:
01-01-2009
01-01-2009
02-01-2009
02-01-2009
03-01-2009
You would expect a value of 3.
For a field, which is a primary key, you would expect a high number of distinct values.
Uniqueness count is the count of unique values.
For a field like transaction date you would expect a low number. You wouldn't expect to find many dates, which have occurred once.
If you had the values:
01-01-2009
01-01-2009
02-01-2009
02-01-2009
03-01-2009
You would expect a uniqueness count of 1.
For a field that is a key you would expect a high number. The uniqueness count should be the same value as the total actual row count.
Thanks Mr.Tcj for your reply..
As i have understand based on the transaction date example,
the cardinality is 3 since it's having the 3 distinct values--- 01-01-2009,
02-01-2009,03-01-2009.
But what about the uniqueness count for the given example?
As you've told uniqueness value is same as that of actual record count.
Then
Transation Date Uniqueness
01-01-2009 2
02-01-2009 2
03-01-2009 1
Total=2+2+1=5(Actual Record count)
Please correct me if i'm wrong..
As i have understand based on the transaction date example,
the cardinality is 3 since it's having the 3 distinct values--- 01-01-2009,
02-01-2009,03-01-2009.
But what about the uniqueness count for the given example?
As you've told uniqueness value is same as that of actual record count.
Then
Transation Date Uniqueness
01-01-2009 2
02-01-2009 2
03-01-2009 1
Total=2+2+1=5(Actual Record count)
Please correct me if i'm wrong..
IBM Certified - Information Server 8.1
The uniqueness count should be the same value as the total actual row count if you are doing a column analysis run on a primary key field.
For example:
1
2
3
4
5
6
7
8
The uniqueness count would be 8 as there are 8 records which only occur once.
The example I supplied the uniqueness count is 1.
There is only one date which occurs once. That is the date
03-01-2009.
Hope that clears that up.
For example:
1
2
3
4
5
6
7
8
The uniqueness count would be 8 as there are 8 records which only occur once.
The example I supplied the uniqueness count is 1.
There is only one date which occurs once. That is the date
03-01-2009.
Hope that clears that up.