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== Cardinality in math ==
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[[User:Troels Arvin|Troels Arvin]] ([[User talk:Troels Arvin|talk]]) 09:17, 29 January 2009 (UTC)
== Low cardinality and use of Index. ==
I am using SAP and one mandatory field in most of the tables that is MANDT. This is taken a s primary key or a part or a secondary index key and becomes a pre included field in all the queries. Even if an ABAPER does not write it so, till it comes as a result of translation by SAP. Typically a production system does not have many client or rather say a few clients only. So this is a very low cardianlity column in most of the table consisting millions of rows...
There is also a rule which says that the indexing a column of low cardinality type to be avoided..
and hence there is the confusion.
What is correct? Indexing or not in a low cardianlity column?
[[Special:Contributions/59.160.30.29|59.160.30.29]] ([[User talk:59.160.30.29|talk]]) 07:21, 25 March 2009 (UTC)Soumen(http://soumen.wordpress.com)
:OK, this is not what talk pages are for, but here it is anyway... Indexing a column of low cardinality makes sense when:
:*using bitmap indexes
:*the column in question is a part of a composite index. [[User:GregorB|GregorB]] ([[User talk:GregorB|talk]]) 19:32, 17 July 2009 (UTC)
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