Index redundance?

Hi,

  If a column is a leading column of a concantenated index (with other some columns), in what condidtion would it be a good idea to create another one column index on this column?

  The simple version of the quesiton is: is this one column index on this column redundant given that it is the leading conlumn of a concantenated index (so we can delete the one-column index)?

  The complex version of the question is, is there any case that makes the addtional index on this column useful, or effecient, or convenient? One consideration is maybe sometime using the one column index on this column is faster or whatever than using the concantenated index if it cover many columns?

  Wish to get an education here. I guess it makes more sense to have a separate single index on a column although this column is part of a concantenated index but not the leading columns of the index.

  Thanks in advance.

  Yu Received on Tue Feb 22 2000 - 17:03:02 CET