In the new Service Tiers for Azure SQL Databases the term DTUs, Database Throughput Unit, plays an important role to know how much predictable performance you have in the different tiers. But what is it and how do it relate to Azure SQL Database Benchmarks (ASDB)?

Database Throughput Unit (ASDB)

It is many factors on a SQL Server that you need to count in when measuring its performance, including CPU and memory. One DTU describes the relative capacity of the performance and is a blended measure of CPU, memory, reads and writes. It means that if you compare 1 DTU with 2 DTU you get double performance in your database.

Here is the list of the service tiers and how many DTUs they have.

Each database server, where the databases are executed, has 1600 DTUs. It means that a server that has 5 Basic databases, 2 S1 datbases and 2 P2 databases consumes 865 DTUs.

Azure SQL Database Benchmark (ASDB)

This is a test suite that Microsoft has created to measure the real throughput of a DTU. It is here we get the real figures of how many transactions a database with a defined number of DTUs has. The description of this test suite can be found here. (It is very important to understand that this test suite probably is not the same as the database you have. Your database can have higher or lower performance that what this test suite result gives.

In the following table the transaction rate, which is the result of running ASDB, is displayed:

Service Tier/Performance Level

DTU

Benchmark Transaction Rate

Predictability

Basic 5 16,600 transactions per hour Good
Standard/S0 10 521 transactions per minute Better
Standard/S1 20 934 transactions per minute Better
Standard/S2 50 2,570 transactions per minute Better
Premium/P1 100 105 transactions per second Best
Premium/P2 200 228 transactions per second Best
Premium/P3 800 735 transactions per second Best