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Unique ID

Auto increment​

  • Hard to scale
  • Do not go up with time across multiple servers

UUID​

  • Non-numeric
  • Do not go up with time
  • 128-bits long

Flickr Ticket server​

  • Centralize auto increment ID in a single database server, called a Ticket Server

Twitter snowflake​

  • Each millisecond, single machine can generate up to 40964096 (2122^{12}) records

Materials​

  • Clock synchronization: Network Time Protocol

  • Snowflake section length tunning