I was examining a script with 'Display Estimated Execution Plan' and it made several recommendations for indexes to add to the database. I added them and the script did indeed run much faster. Now I'm looking at putting these into our standard form for inclusion into our regular upgrade scripts and I noticed what might be a redundancy:
CREATE NONCLUSTERED INDEX [TableA_ColA] ON [dbo].[TableA] ([ColA]) INCLUDE ([ColB]) GO CREATE NONCLUSTERED INDEX [TableA_ColB_ColA] ON [dbo].[TableA] ([ColB],[ColA]) GO
I can see from the documentation that there are some differences between the two indexes as far as space usage is concerned, but in this case
nvarchar(255), well under the 900 byte limit, so I'm not sure that the
INCLUDE in the first index is necessary.
So is this just an arbitrary result of the execution plan analyser? It seems to me if I have the second index the first one is redundant?