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Asked: 2026-05-24T08:46:56+00:00

In Oracle 10g, does it matter what order create index and alter table comes

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In Oracle 10g, does it matter what order create index and alter table comes in?

Say i have a query Q with a where clause on column C in table T. Now i perform one of the following scenarios:

  1. I create index I(C) and then add columns X,Y,Z.
  2. Add columns X,Y,Z then create index I(C).

Q is ‘select * from T where C = whatever’

Between 1 and 2 will there be a significant difference in performance of Q on table T when T contains a very large number of rows?

I personally make it a practice to do #2 but others seem to have a different opinion.

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  1. Editorial Team

    It makes no difference if you add columns to a table before or after creating an index. The optimizer should pick the same plan for the query and the execution time should be unchanged.

    Depending on the physical storage parameters of the table, it is possible that adding the additional columns and populating them with data may force quite a bit of row migration to take place. That row migration will generate changes to the indexes on the table. If the index exists when you are populating the three new columns with data, it is possible that populating the data in X, Y, and Z will take a bit longer because of the additional index maintenance.

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