Index databases
In general, the fastest way to access data from a database is to use an index. Indexes increase the efficiency of finding a specific piece of data. Indexing provides an efficient and fast way to identify the data (rows) in a table.
Recommendations:
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Index every primary key and most foreign keys in the database.
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Always index audience ID fields.
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Index columns that are joined in queries.
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Index columns involved in ORDER BY and GROUP BY.
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Index columns that perform sorting operations, including UNION and DISTINCT.
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Consider indexing any attributes that are frequently referenced in SQL WHERE clauses.
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Use an index for both equality and range queries.
When you use indexing, keep the following guidelines in mind:
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Add indexes only when absolutely necessary. Indexes significantly impact INSERT, UPDATE, and DELETE performance, and they require storage.
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Avoid or remove redundant indexes. For example, two indexes that use the same or similar columns make query optimization more complicated and consume more storage.
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Carefully choose one clustered index for each table.
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Avoid indexing columns that consist of LONG character strings.
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