Indexing a table

hi
if searching and updating a large database is required in realtime then indexing increases the performance a lot. I had doubt regarding the order of columns in which indexing needs to be done 1). when a compound index is t be created then what should be the order of the fields in the index. The common field which is same for a large no of rows should be the first column to be included in index or should be the last.

2). while operating on views does the index of the tables which are constituting the view are used as it is , and shoul a separate index needs to be created on the columns appearing tin the where clause of the view independently even though a composite index exists over the where clause of the view creation sql + the where clause of the query from the view.

e.g. create view a as select b.x,c.y,c.z,c.xx

     from tableb b, tablec c,
     where b.x=c.y;
 

a query is made as "select * from a where xx="some value";

existing index on c.y + c.xx

should a new index over only c.xx and only c.y and only b.x is is required

any suggestions in this regard will be very useful thanks Received on Tue Jul 25 2000 - 10:19:10 CDT