Design a Blogging Platform

Why sometimes soft work over hard delete

• Recoverability, Archival, Audit
• Easy on the database engine (No tree re-balancing, but often depends on database internals)

Storing datetime in DB as:

• datetime object
  • serializing and deserializing is required
  • convenient
  • sub-optimal
  • heavy on size and index
• epoch integer
  • efficient
  • optimal
  • lightweight
  • comparisons are easy
  • Readability is an issue so conversion should be done
  • Only a limited range of date can be stored based on size of the integer
• custom format integer (eg. YYYYMMDD)
  • Readability and benefits of integer
  • There is no hard and fast rule, be flexible everything has it’s own trade-off

<aside> 💡 Read MySQL Datetime format from documentation

</aside>

Caching is anything that reduces response times by saving any heavy computation.

• Cache are not always RAM.
• Reduce Disk I/O or Network I/O or compute
• Cache are just glorified Hash Tables with some advanced data structures

Design Online Offline Indicator

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Failure detection in a distributed system

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Design Slack's Realtime Communication