# Distributed Data and Computation · checkpoint worksheet

## 1 · Bottleneck

Workflow:  
Data size / rows:  
Elapsed time:  
Plan or system clue:  
Simplest plausible fix:

## 2 · Map / shuffle / reduce

Partition key:  
Map output:  
Shuffle key:  
Reduce output:  
Likely skew:  
Why PostgreSQL is or is not already sufficient:

## 3 · Scale recommendation

Choose: one database / object-storage partitions / distributed compute  
Evidence:  
Acceptance threshold:  
New failure mode introduced:  
Trigger to reconsider: