DVA-02-Notes/Study/DynamoDB/ReadWriteUnits.md

Read / Write Capacity Units

This is for _DynamoDB.

The general formula for $CU$s is

\begin{aligned}
rHz =& \frac{kCU / m}{ceil(nKB/bKB)} \\\ \\
kCU =& ceil(nKB / bKB) \times rHz \times m \\\ \\
\text{where:} \\
nKB =& \text{ input size in KB} \\
bKB =& \text{ operation block size: 1KB for Writes and 4KB for Reads} \\
rHz =& \text{ request rate} \\
m =& \text{ modifier: } \\
&0.5\text{ for eventually consistent operations, } \\ 
&1\text{ for normal operations, } \\
&2\text{ for transactional operations}
\end{aligned}

See Read and Write Units - Set 3 for some examples.