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Overview of Data Management Services in Azure

Updated: April 9, 2014

The Azure Platform offers following data management services:

 

Data Management Service

Purpose

Azure Table service

Provides durable storage for structured data.

Azure Blob service

Provides durable storage for large binary objects such as video or audio.

Microsoft Azure SQL Database

Relational Database Management System.

These offerings are hosted in Azure data centers and are available to your applications whether they are running on-premises, hosted within an Azure data center, or hosted within a competing cloud service. The data storage offerings provide many benefits such as high availability, scalability, easy manageability, limitless storage, and security. See Azure Data Management topic for more details.

If you are running your application code in an Azure data center, then the virtual machine (VM) that is hosting your application exposes an additional storage option: Azure Drives. An Azure drive provides a durable drive that is backed by a page blob. In addition, you can also use local storage on the VM, which provides a temporary storage for an application instance.

Authors: Sreedhar Pelluru
Contributors: James Podgorski, Silvano Coriani
Reviewers: Christian Martinez, Steve Howard, Kun Cheng, Paolo Salvatori, Shawn Hernan

Azure Table Service

Table service offers a massively scalable non-relational structured storage in the cloud. It provides a non-relational key/property-bag collection useful for storing tabular data such as customer information, orders, news feeds, and game scores. If you have structured data that is currently stored in a SQL Server database or any other data store and does not require server-side computation such as joins, sorts, views, and sorted procedures, consider storing that data in Azure Tables. See Migrating Data to Azure Table Storage for more details.

Azure Blob Service

Blob service provides a way to store large amounts of unstructured, text or binary data, such as pictures, audio, and video files. If your application stores large binary objects in a SQL Server database or stores large amount of unstructured data on a file system, consider using the Azure Blob service. See Migrating Data to Azure Blob Storage for more details.

Azure SQL Database

Microsoft Azure SQL Database provides a Relational Database Management System based on SQL Server technology. Microsoft Azure SQL Database exposes a tabular data stream (TDS) interface, and Transact-SQL (T-SQL), so many of the tools and applications that work with SQL Server also work with Microsoft Azure SQL Database. Applications written using existing technologies such as ADO.NET and ODBC to communicate with SQL Server can be updated to access Microsoft Azure SQL Database with minimal code changes. Microsoft Azure SQL Database also provides standard SQL Server features such as stored procedures, views, multiple indexes, joins, and aggregations.

If your application uses a SQL Server database, you could easily migrate the database to a Microsoft Azure SQL Database. However, if the application uses SQL Server features that Microsoft Azure SQL Database does not support, you will need to modify the database solution design. See Migrating SQL Server Databases to Azure SQL Database section for the detailed information.

Azure SQL Database vs. Table Storage

The Table Storage stores structured data as Azure SQL Database does. Therefore, when migrating applications from on-premises to the Azure Platform, a common question that arises is whether to use Table Storage or Azure SQL Database.

The main difference between Azure SQL Database and Table Storage is that Azure SQL Database is a relational database management system that provides the data-processing capabilities through queries, transactions, and stored procedures that are executed on the server side. Whereas, Table Storage does not provide a relational data store or the data-processing capabilities that Azure SQL Database supports. Therefore, if your application stores and retrieves large data sets but does not require server-side data processing, the Azure Table is a better choice. If your application requires data-processing over large data sets, then Azure SQL Database is a better choice.

There are several other factors you need to consider before deciding between Azure SQL Database and Azure Table Storage. The following table compares features of Azure Table Storage with Azure SQL Database.

 

Comparison Criteria Table Storage Azure SQL Database

Maximum Entity Size

Entities in Table Storage are limited to 1 MB each with no more than 255 properties that include three required properties: PartitionKey, RowKey, Timestamp.

Rows can be up to 8 MB in size, and can contain 1024 columns.

Data Relationships

No. Table Storage does not provide any way to represent relationships between data.

Yes. Azure SQL Database allows you to define relationship between data stored in different tables by using foreign keys.

Server-side Processing

Table Storage supports basic operations such as insert, update, delete, and select. It does not support joins, stored procedures, triggers, or any processing on the storage engine side, such as SQL Database does.

Azure SQL Database provides standard SQL Server features such as stored procedures, views, multiple indexes, joins, and aggregations.

Transaction support

Limited. Table Storage supports transactions for entities in the same table and the same partition. Up to 100 operations are supported in a transaction. Table store supports optimistic concurrency.

See Entity Group Transactions for more details.

Yes. Azure SQL Database supports typical ACID transactions within the same database. Transactions are not supported across databases. Azure SQL Database also supports optimistic concurrency.

High Availability/Fault Tolerance

Yes. Tables stored on Azure are replicated to three locations within the same data center for resiliency against hardware failures.

Yes. Three copies of a Azure SQL Database are maintained within the data center you choose.

Geo replication

Yes. Azure tables are replicated between two geographically separated data centers on the same continent, to provide additional data durability in the case of a major disaster.

No. A Azure SQL Database is not replicated to other regions by default.

Maximum Data Size

100 TB for each storage account. A storage account (tables, blobs, and queues together) is allowed to store 100 TB of data. Therefore, maximum size of an Azure table is 100 TB.

150 GB for each database. For additional information on how to store larger databases, see Scaling Out Azure SQL Databases.

Management Protocol and Tools

REST over HTTPS. You can use Azure Storage Explorer from CodePlex or other third-party tools such as Cloud Storage Studio.

REST over HTTPS (or) TDS over SSL. You can use the or SQL Server Management Studio to manage a Azure SQL Database. These tools use TDS (Tabular Data Stream) protocol over an SSL (Secure Socket Layer) connection to access a Azure SQL Database.

Data Access

The data stored in the Table Storage can be accessed by using the HTTP(S) REST API or .NET Client Library for WCF Data Services. See How to Use the Table Storage.

Applications written using existing technologies such as ADO.NET and ODBC that communicate with SQL Server can be used to access Azure SQL Database with minimal code changes.

Azure SQL Database is accessible to applications that run in , on-premises or on non- cloud platforms.

Schema for a table

No fixed schema. Each entity (row) can have different properties. For example, you can store order information in one row and customer information in another row of the same table.

Fixed schema for the table once defined but can be altered at any time. All rows must adhere to the schema rules.

Supported Data Types

Byte array, Boolean, DateTime, Double, GUID, Int32, Int64, String

See SQL Database Supported Data Types.

Cost

See Azure Pricing Details.

See Azure Pricing Details.

Java API Support

Yes

Yes

Node.js API Support

Yes

No. Currently not supported.

Authentication

256-bit Symmetric Key is used to authenticate users.

SQL Authentication is used to authenticate users who access a Azure SQL Database instance.

Azure Platform Management Portal uses Windows Live ID to authenticate users.

Similarity with existing data stores used on-premises.

No.

Similar to SQL Server with some limitations.

Accessible from on-premise applications or applications hosted in non-Azure platforms

Yes

Yes

See Also

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