DynamoDB Primary Key Concept

 

DynamoDB Primary Key Concept

DynamoDB এ primary key হলো table এর main identifier।
Primary key দুইভাবে হতে পারে:

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Option 1 — Simple Primary Key

1. Partition Key only

2. প্রতিটি item table এ unique Partition Key দ্বারা uniquely identified হয়

Example: Users table

Partition Key (user_id)	name	age
1	Ali	24
2	Sara	22

এখানে primary key = Partition Key = user_id

Sort Key নেই → এক Partition Key এ শুধু ১টি item allowed

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Option 2 — Composite Primary Key

1. Partition Key + Sort Key

2. এখন primary key = combination of Partition Key + Sort Key

3. একই Partition Key এর multiple items allowed, কিন্তু Sort Key different হতে হবে

Example: Orders table

Partition Key (user_id)	Sort Key (order_date)	item
1	20260101	Laptop
1	20260105	Mouse
2	20260102	Keyboard

Primary key uniqueness check করে (Partition Key + Sort Key) combination দিয়ে

Partition Key alone unique না → multiple items same user_id allowed

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2️⃣ Key Takeaway

Concept	DynamoDB
Partition Key	Main part of primary key, always required
Sort Key	Optional, second part of primary key (for composite key)
Primary Key	Either:
1️⃣ Partition Key only (Simple)
2️⃣ Partition Key + Sort Key (Composite)

💡 মনে রাখো: Partition Key alone defines data distribution / shard,
Sort Key defines ordering inside that partition

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Example 

Simple key table:

Primary Key = user_id
Partition Key only

Composite key table:

Primary Key = (user_id + order_date)
Partition Key = user_id
Sort Key = order_date

• Query efficiency depends on Partition Key

• Sort Key gives extra flexibility for multiple items per Partition Key

   

   

   

  tar mane primary key er 2 ta part ache primary key = partition key + short key (composite key)

   but main primary key hocche partition key