Ravi Sir's Cards › AWS
Write sharding
This revision card explains Write sharding. A single hot writer key will not scale with more RCU alone. It describes append shard suffixes; fan-in on read or project to a GSI for aggregates. The how-to section notes estimate peak per PK , then pick shard count , then document fan-in. An example on the card is omar Haddad documents shard count next to the table name in the runbook.
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What this card says
Why do we need it?
A single hot writer key will not scale with more RCU alone.
What is it?
Append shard suffixes; fan-in on read or project to a GSI for aggregates.
write sharding
How to do it
Estimate peak per PK → pick shard count → document fan-in.
Example
Omar Haddad documents shard count next to the table name in the runbook.