Adding indices after table creation
Indices are a general concept in computing. This book also has an index for faster lookup, which matches concepts to page numbers. An index takes up space; in the case of this book, a couple of pages. Database indices have the added disadvantage that they make inserts and updates slower because of the extra overhead of updating the index. Usually, primary and foreign keys automatically get an index, but this depends on the database implementation.
Adding indices should not be taken lightly, and this is best done after consulting database administrators. Alembic has features for index addition similar to the features that we saw in the Adding a table column to an existing table recipe.
Getting ready
Refer to the ...
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