Table storage basics in Azure - Step-by-Step Execution

Process Flow - Table storage basics

Create Storage Account

↓

Create Table in Storage

↓

Insert Entity (Row) into Table

↓

Query Entities by PartitionKey and RowKey

↓

Update or Delete Entity

↓

Access Data via SDK or REST API

This flow shows how you create a storage account, add a table, insert data rows called entities, query them, and update or delete as needed.

Execution Sample

Azure

Create table 'Customers'
Insert entity PartitionKey='USA', RowKey='001', Name='Alice'
Query entity PartitionKey='USA', RowKey='001'
Update entity PartitionKey='USA', RowKey='001', Name='Alice Smith'
Delete entity PartitionKey='USA', RowKey='001'

This sequence creates a table, adds a customer record, retrieves it, updates the name, then deletes the record.

Process Table

Step	Action	PartitionKey	RowKey	Name	Result
1	Create Table	-	-	-	Table 'Customers' created
2	Insert Entity	USA	001	Alice	Entity inserted
3	Query Entity	USA	001	-	Found entity with Name='Alice'
4	Update Entity	USA	001	Alice Smith	Entity updated
5	Query Entity	USA	001	-	Found entity with Name='Alice Smith'
6	Delete Entity	USA	001	-	Entity deleted
7	Query Entity	USA	001	-	No entity found

💡 Entity deleted at step 6, so query at step 7 finds no entity.

Status Tracker

Variable	Start	After Step 2	After Step 4	After Step 6
Table 'Customers'	Empty	Contains 1 entity	Contains 1 updated entity	Empty

Key Moments - 2 Insights

Why do we need both PartitionKey and RowKey to identify an entity?

PartitionKey groups entities for fast queries and scalability; RowKey uniquely identifies an entity within that partition. Together they form a unique key as shown in execution_table steps 3 and 4.

What happens if we query an entity after deleting it?

As shown in step 7, the query returns no entity because it was deleted at step 6.

Visual Quiz - 3 Questions

Look at the execution table, what is the Name of the entity after step 4?

A Alice Smith

B Alice

C No entity

D USA

💡 Hint

Check the 'Name' column in row for step 4 in execution_table.

At which step does the table become empty again?

A Step 2

B Step 4

C Step 6

D Step 7

💡 Hint

Look at variable_tracker after step 6 and execution_table step 6.

If we insert another entity with the same PartitionKey and RowKey as step 2, what happens?

A A new entity is added alongside the old one

B The old entity is overwritten

C An error occurs

D The table is deleted

💡 Hint

Table storage uses PartitionKey and RowKey as unique keys, so inserting same keys updates the entity.

Concept Snapshot

Azure Table Storage stores data as entities in tables.
Each entity has a PartitionKey and RowKey to uniquely identify it.
PartitionKey groups entities for fast queries and scalability.
RowKey uniquely identifies an entity within a partition.
You can insert, query, update, and delete entities.
Access is via SDKs or REST API.

Full Transcript

This lesson shows how Azure Table Storage works step-by-step. First, you create a storage account and then a table named 'Customers'. You insert an entity with PartitionKey 'USA' and RowKey '001' and name 'Alice'. When you query this entity, you find it by these keys. You can update the entity's name to 'Alice Smith' and confirm the update by querying again. Finally, you delete the entity and see that querying it returns no result. PartitionKey and RowKey together uniquely identify each entity, enabling fast and scalable access. This simple flow helps beginners understand how to store and manage data in Azure Table Storage.

Practice

1. What two keys uniquely identify a record in Azure Table Storage?

easy

A. StorageKey and DataKey

B. PrimaryKey and SecondaryKey

C. PartitionKey and RowKey

D. TableKey and RecordKey

Solution

1. Step 1: Understand Azure Table Storage keys

   Azure Table Storage uses two keys to uniquely identify each record: PartitionKey and RowKey.

2. Step 2: Confirm uniqueness of keys

   PartitionKey groups records, and RowKey uniquely identifies a record within that partition.

3. Final Answer:

   PartitionKey and RowKey -> Option C

4. Quick Check:

   Unique record ID = PartitionKey + RowKey [OK]

Hint: Remember: PartitionKey groups, RowKey identifies [OK]

Common Mistakes:

• Confusing PartitionKey with PrimaryKey
• Thinking TableKey is a valid key
• Assuming only one key is needed

2. Which of the following is the correct way to create a table client in Azure SDK for Table Storage?

easy

A. TableClient = new TableServiceClient(tableName).GetTableClient(connectionString);

B. TableClient = new TableClient(tableName, connectionString);

C. TableClient = new TableServiceClient(tableName).GetClient(connectionString);

D. TableClient = new TableClient(connectionString, tableName);

Solution

1. Step 1: Review Azure Table Storage SDK syntax

   The correct constructor for TableClient requires connection string first, then table name.

2. Step 2: Match syntax to options

   TableClient = new TableClient(connectionString, tableName); matches the correct syntax: new TableClient(connectionString, tableName); others mix order or use wrong classes.

3. Final Answer:

   TableClient = new TableClient(connectionString, tableName); -> Option D

4. Quick Check:

   Constructor order: connectionString, tableName [OK]

Hint: Connection string always comes before table name [OK]

Common Mistakes:

• Swapping connection string and table name order
• Using TableServiceClient instead of TableClient
• Calling non-existent methods like GetClient

3. Given this code snippet, what will be the output?

var entity = new TableEntity("users", "user1") { { "Name", "Alice" }, { "Age", 30 } };
Console.WriteLine(entity.PartitionKey + ", " + entity.RowKey + ", " + entity["Name"]);

medium

A. user1, users, Alice

B. users, user1, Alice

C. users, user1, 30

D. user1, users, 30

Solution

1. Step 1: Identify PartitionKey and RowKey values

   PartitionKey is "users" and RowKey is "user1" as set in the constructor.

2. Step 2: Access the "Name" property value

   The "Name" property is set to "Alice", so entity["Name"] returns "Alice".

3. Final Answer:

   users, user1, Alice -> Option B

4. Quick Check:

   PartitionKey, RowKey, Name = users, user1, Alice [OK]

Hint: PartitionKey first, RowKey second, then properties [OK]

Common Mistakes:

• Mixing PartitionKey and RowKey order
• Printing Age instead of Name
• Confusing property access syntax

4. You try to insert an entity with the same PartitionKey and RowKey twice. What will happen?

medium

A. An error occurs because keys must be unique.

B. The table creates a duplicate record with a new key.

C. The second insert overwrites the first entity silently.

D. The insert is ignored without error.

Solution

1. Step 1: Understand uniqueness constraint in Table Storage

   PartitionKey and RowKey together uniquely identify an entity; duplicates are not allowed.

2. Step 2: Behavior on duplicate insert

   Trying to insert an entity with existing keys causes an error, preventing duplicates.

3. Final Answer:

   An error occurs because keys must be unique. -> Option A

4. Quick Check:

   Duplicate keys cause error, no silent overwrite [OK]

Hint: Duplicate keys cause error, not overwrite [OK]

Common Mistakes:

• Assuming silent overwrite happens
• Thinking duplicates are allowed
• Believing insert is ignored silently

5. You want to design a scalable Azure Table Storage schema for a large user database. Which approach best supports fast lookups and scalability?

hard

A. Use PartitionKey as user country and RowKey as user ID

B. Use PartitionKey as user ID and RowKey as timestamp

C. Use a single PartitionKey for all users and RowKey as user ID

D. Use random GUIDs for both PartitionKey and RowKey

Solution

1. Step 1: Understand partitioning for scalability

   PartitionKey groups data to distribute load; grouping by country balances partitions.

2. Step 2: Use RowKey for unique identification

   RowKey as user ID uniquely identifies users within each country partition.

3. Step 3: Evaluate other options

   Single partition causes bottleneck; random GUIDs reduce query efficiency; user ID as PartitionKey fragments data poorly.

4. Final Answer:

   Use PartitionKey as user country and RowKey as user ID -> Option A

5. Quick Check:

   Partition by country, RowKey unique ID = scalable [OK]

Hint: PartitionKey groups data logically for scalability [OK]

Common Mistakes:

• Using single partition for all data
• Random keys hurting query performance
• Misusing RowKey as partitioning key