# Overview Of Indexes
+ Index: Pointer to row records to speed up data retrieval 
  + Quickly find row records in a table
  + Avoid full table scan
  + Improve query performance
+ The following TiDB constraints provide indexes by default:
  + Primary Key
  + Unique key
+ Can also be created with the**CREATE INDEX** statement
+ `information_schema.tidb_indexes` 
  + Index name: `KEY_NAME`  
+ `SHOW INDEX FROM <table_name>;` Get the definition of an index
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