We have a wide dataset that isn't very tall (say 250K rows, 90 columns). We will be providing users with an interface that allows them to generate arbitrary queries against this dataset. They can select any number of columns, rows; they can filter by, group by, sort by and aggregate by any columns they want.
This table is actually 'precomputed' from a set of relational tables; this precomputed tables is 90 columns wide and will be used solely for the users' queries. This big flat table will be produced just once a day.
Because we have no idea in advance what they will actually be doing these operations against, we were suggested to place an index on every column of the table.
My question is, would this have any adverse effects?
We would also want this 'methodology' to extend to future datasets that we provide similar functionality on; 1.7 million rows with 120 columns
For reference, we are using SQL Server 2008 R2.