# Calculating the `Safe Point`    

+ Calculating the `safepoint`
  + `Current time - GC life time`
    + `GC` life time: 10 minutes by default 
+ `v4.0:` `GC` blocks by **`min_start_ts`** of alive transactions (sessions) in the cluster
  + `Safe Point ≤ min_start_ts` among all sessions

+ `v4.0:` Service safepoints (explained later)
  + Registered by other components (`TiCDC`, `BR`, ...)
  + The minimum one blocks `GC`
  + `Safe Point ≤ min_service_safe_point`

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