When and How Should Indexes Be Used to Enhance Database Performance?

DOs and DONTs for Enhancing Database Performance with Indexes

To optimize database performance, it's crucial to adhere to key principles while managing indexes. Here are some essential DOs and DONTs:

DOs:

• Create indexes for conditions frequently used in WHERE clauses. Indexes accelerate queries by quickly accessing data based on specified criteria.
• Use indexes for sorting, especially with limits. Indexes enable efficient sorting of results, significantly improving query performance when combined with limit clauses.
• Consider multicolumn indexes when multiple conditions or sorting criteria apply. By ordering columns in the index according to their usage, multicolumn indexes improve both filtering and sorting operations.
• Keep table statistics up-to-date. Accurate table statistics ensure that the optimizer can effectively utilize indexes.
• Use partial/expression indexes when appropriate. Partial indexes and expression indexes can significantly reduce index size while maintaining their effectiveness in specific scenarios, such as excluding specific values or applying expressions to columns.

DONTs:

• Avoid unnecessary indexes. Each index incurs additional write overhead, so it's essential to create indexes only when necessary.
• Index data used primarily for filtering. Indexes are primarily used for filtering data quickly. If a column is frequently used for retrieval rather than filtering, an index may not be beneficial.
• Create indexes on columns with high cardinality. Creating an index on a field with many unique values, known as high cardinality, can lead to excessive index fragmentation and performance degradation.
• Neglect table repartition. The table's repartition strategy can impact index effectiveness. If the index is not aligned with the physical distribution of data, a full table scan may be more efficient than an index scan.

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