# The Cost of Indexing
+ Do NOT create unnecessary indexes in TiDB
+ Data modifications are slower in tables that have many indexes
  + Affected indexes must also be updated 
  + Negatively impacts the write-intensive workloads significantly
+ Indexes consume disk space
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While indexes can significantly enhance query performance, they can negatively impact data modification statements because they must be updated whenever the referenced rows change. Avoid creating indexes that are not utilized by your queries, and regularly audit your indexes when adding, modifying, or retiring queries.

Since each secondary index references the primary key index, which contains the table data, do not remove the `PRIMARY` index, even if you believe it is no longer being used.