From e748808730502fdebcef466dafa10921dedc6e7f5f3d8c7cb765b1ed5b10213f Mon Sep 17 00:00:00 2001
From: Rijndael <rijndael@baldy.ga>
Date: Mon, 2 Nov 2026 21:19:45 +0000
Subject: [PATCH] dynamodb

---
 DynamoDB/ReadWriteUnits.md | 28 ++++++++++++++++++++++++++++
 DynamoDB/_DynamoDB.md      |  3 +++
 2 files changed, 31 insertions(+)
 create mode 100644 DynamoDB/ReadWriteUnits.md
 create mode 100644 DynamoDB/_DynamoDB.md

diff --git a/DynamoDB/ReadWriteUnits.md b/DynamoDB/ReadWriteUnits.md
new file mode 100644
index 0000000..b1149bb
--- /dev/null
+++ b/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.
+$$
+\begin{aligned}
+cr &= \text{consistent read} \\
+ecr &= \text{eventually consistent read} \\
+tr &= \text{transactional read} \\
+\ \\
+1\ RCU &= 4kb/cr/s \\
+\frac{1}{2}\ RCU &= 4kb/ecr/s \\
+2 RCU &= 4kb/tr/s
+\end{aligned}
+$$
diff --git a/DynamoDB/_DynamoDB.md b/DynamoDB/_DynamoDB.md
new file mode 100644
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+++ b/DynamoDB/_DynamoDB.md
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+# DynamoDB
+DynamoDB is a managed Key/Value NoSQL database.
+