dynamodb

DynamoDB/ReadWriteUnits.md

@@ -0,0 +1,28 @@
+# Read / Write Capacity Units
+This is for [[_DynamoDB|DynamoDB]].
+
+## Writing
+Math goes sort of like this:
+$$
+\begin{aligned}
+w &= \text{write} \\
+tw &= \text{transactional write} \\
+\ \\
+1\ WCU &= 1\ kb/w/s \\
+2\ WCU &= 1\ kb/tw/s \\
+\end{aligned}
+$$
+Take away is that a 1KB write is 1WCU. And a 1KB [transactional]{.underline} write is 2WCU.
+## Reading
+The math for reading is a little bit more convoluted, because the reads are divided by 4KB blocks.
+$$
+\begin{aligned}
+cr &= \text{consistent read} \\
+ecr &= \text{eventually consistent read} \\
+tr &= \text{transactional read} \\
+\ \\
+1\ RCU &= 4kb/cr/s \\
+\frac{1}{2}\ RCU &= 4kb/ecr/s \\
+2 RCU &= 4kb/tr/s
+\end{aligned}
+$$

DynamoDB/_DynamoDB.md

@@ -0,0 +1,3 @@
+# DynamoDB
+DynamoDB is a managed Key/Value NoSQL database.
+