# Placement Rules in SQL

+ Placement Rules in SQL is a feature that enables you to specify where data is stored in a TiKV cluster using SQL interfaces. 
+ Using Placement Rules in SQL, tables and partitions are scheduled to specific regions, data centers, racks, or hosts. This is useful for scenarios including optimizing a high availability strategy with lower cost, ensuring that local replicas of data are available for local stale reads, and adhering to data locality requirements.

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+ User scenarios examples:
  + Merge multiple databases of different applications to reduce the cost on database maintenance
  + Increase replica count for important data to improve the application availability and data reliability
  + Store new data into NVMe storage and store old data into SSDs to lower the cost on data archiving and storage
  + Schedule the leaders of hot-spot data to high-performance TiKV instances
  + Separate cold data to lower-cost storage mediums to improve cost efficiency
  + Support the physical isolation of computing resources between different users, which meets the isolation requirements of different users in a cluster, and the isolation requirements of CPU, I/O, memory, and other resources with different mixed loads