CODEWITHSUNDEEP
azure-sql-database
Munchkin
Munchkin

Reputation: 4946

Difference between single and elastic SQL Database

I'm a little confused about these two types of databases. For my understanding, elastic databases are just a cluster of single databases, right? So if that's true, I don't get the different limitation on them, for example:

1) I choose Standard 800 elastic pool but it contains only two S1 single databases (20 DTU each) then I have a maximum of 40 DTU (=2*20DTU) and not 800 DTU?

2) Same scenario: With two S1 single databases i have 2*250GB = 500GB storage limit, but Standard 800 elastic pool offers 800GB storage limit - how much storage can I use?

3) I want to put three S3 single DBs (100 DTU and 250GB each = 300DTU and 750GB) together: So I can't choose a S-100 elastic DB because this one has a limit of 100eDTU and 100GB ?

Upvotes: 3

Views: 9927

Answers (1)

user5543454
user5543454

Reputation: 76

Yes, it's correct that an elastic pool is a shared pool of compute (i.e., DTU) and storage resources, but there are limits on individual databases within it.

In your examples:

Scenario 1. You can set the max DTU cap per databases to 20 DTUs, but one of the advantages of elastic pools is that this limit can be up to 100 DTUs for Standard pools. So with an 800 DTU Standard pool and two databases each database can peak up to 100 DTUs (S3 level of performance). In fact, with 800 DTUs, 8 databases could peak up to 100 DTUs simultaneously.

Scenario 2. With a Standard 800 DTU elastic pool offers, it's correct that 800 GB is the storage limit for the total storage across all databases within it. Because it's a Standard pool, the max storage per database is 250 GB. So, for example, three databases can use 250 GB each for a total of 750 GB, or 80 databases could each use 10 GB for a total of 800 GB. Etc.

Scenario 3. If all three databases each need to burst to 100 DTUs at the same time and each database needs to use 250 GB, then it's correct they wouldn't fit into the a 100 DTU pool.

Upvotes: 6

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