Programming Guide for Azure Storage Tables

This guide provides essential information and best practices for interacting with Azure Storage Tables using various programming models.

Understanding Table Entities

Azure Storage Tables store data as entities. An entity is a set of properties, similar to a row in a database table. Each entity must have two system properties:

• PartitionKey: Used for partitioning the table. Entities with the same PartitionKey are guaranteed to be co-located.
• RowKey: Uniquely identifies an entity within a partition.

All other properties are user-defined and can be of various data types, including String, DateTime, Boolean, GUID, Double, Int32, Int64, and Binary. There is no schema enforcement at the table level, allowing for flexible data structures.

Key Operations

The primary operations you'll perform on Azure Storage Tables include:

• Creating Tables: You can create new tables to store your data.
• Inserting Entities: Add new data records to a table. You can insert single entities or batch multiple inserts.
• Querying Entities: Retrieve data from tables based on specified criteria. This includes filtering, sorting, and selecting specific properties.
• Updating Entities: Modify existing data records.
• Deleting Entities: Remove data records from a table.
• Batch Operations: Group multiple operations (inserts, updates, deletes) into a single request for efficiency.

Using the Azure Storage SDKs

The Azure Storage SDKs offer convenient and type-safe ways to interact with Storage Tables from your applications. Libraries are available for .NET, Java, Python, Node.js, and Go.

Example: Inserting an Entity (C# SDK)

using Azure.Data.Tables;

// Replace with your actual connection string
string connectionString = "YOUR_AZURE_STORAGE_CONNECTION_STRING";
string tableName = "MyEntityTable";

TableClient tableClient = new TableClient(connectionString, tableName);

// Create the table if it doesn't exist
tableClient.CreateIfNotExists();

// Define the entity
var entity = new TableEntity("PartitionA", "Row1")
{
    { "FirstName", "Jane" },
    { "LastName", "Doe" },
    { "Age", 30 },
    { "IsActive", true }
};

// Insert the entity
tableClient.AddEntity(entity);

Console.WriteLine("Entity inserted successfully.");
            

Example: Querying Entities (Python SDK)

from azure.data.tables import TableServiceClient

# Replace with your actual connection string
connection_string = "YOUR_AZURE_STORAGE_CONNECTION_STRING"
table_name = "MyEntityTable"

table_service_client = TableServiceClient.from_connection_string(connection_string)
table_client = table_service_client.get_table_client(table_name=table_name)

# Query for entities in PartitionA where Age is greater than 25
filter = "PartitionKey eq 'PartitionA' and Age gt 25"
for entity in table_client.query_entities(filter=filter):
    print(f"Found Entity: {entity['RowKey']}, Name: {entity['FirstName']} {entity['LastName']}, Age: {entity['Age']}")
            

Understanding OData Filter Syntax

When querying tables, you use an OData filter expression to specify criteria. Common operators include:

• Comparison: eq (equals), ne (not equals), gt (greater than), ge (greater than or equal to), lt (less than), le (less than or equal to)
• Logical: and, or, not
• Arithmetic: add, sub, mul, div, mod
• String functions: startswith, endswith, substringof, length, tolower, toupper

For detailed syntax, refer to the Azure Storage REST API documentation.

Batch Operations

Batch operations allow you to group multiple entity operations (insert, update, delete) into a single HTTP request. This is highly recommended for improving performance and reducing the number of network round trips.

Performance Considerations

• PartitionKey Design: Distribute your data evenly across partitions to avoid hot spots.
• Query Efficiency: Filter queries as much as possible on PartitionKey and RowKey. Use $select to retrieve only the properties you need.
• Batching: Use batch operations for multiple entity modifications.
• Select Properties: Avoid selecting all properties if you only need a few.

Next Steps

Explore the following resources to deepen your understanding:

• Azure Storage Tables REST API Reference
• Querying Azure Storage Tables
• Optimizing Azure Storage Table Performance