# Slow Reads Troubleshooting Ideas (A)
+ Determine the direction of investigation by phenomenon:
  + The overall response of the cluster is slow
    + Confirm the problem component TiDB, TiKV, or PD
  + A SQL statement is slow to respond
    + Slow Query Locates slow queries that continue to occur
    + TiDB Dashboard slow query target slow SQL statement

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TiDB Cluster itself is a complex distributed database system. It is divided into TiDB Server, PD Server and TiKV Server. Each component has different roles. When read request are slow, which component is the bottleneck that needs to be located, and which of the following situations occurs:

- The overall response of the cluster is slow
  - Need to further clarify where the slowness is, TiDB, TiKV or PD
- Only one SQL execution takes longer
  - Grafana shows that there is no obvious upward trend in TiDB Duration, but there is a persistent slow query phenomenon in Slow Query
  - TiDB Dashboard Slow Query Target Slow SQL