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sakuraime avatar image
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sakuraime asked sakuraime commented

Always-on DTC support

I am reading the following page
https://techcommunity.microsoft.com/t5/core-infrastructure-and-security/msdtc-supported-configurations/ba-p/371456

if I am choosing to use Local DTC . on SQL Server 2019 AAG, what's the difference between enabling 'Per Database dtc support' or not ?

And any further setting required on the Local DTC like in the following page ?

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Any other recommendation while doing the DTC logging ?

sql-server-general
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Cathyji-msft avatar image
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Cathyji-msft answered sakuraime commented

Hi @sakuraime,

You need to create the availability group using the WITH clause of DTC_SUPPORT = PER_DB when you want to create an availability group for distributed transactions.

SQL Server will use the local DTC out of the box by default.

Suggest you read the blog MSDTC Best Practices with an Availability Group to get the detail information.


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what's the difference between enabling DTC_SUPPORT = PER_DB or not ??

And any further setting required on the Local DTC like in the following page ? on the servers with AAG as well as the others SQL instances (which outside the aag ) .

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I just see the following limitation

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32 databases ? May I know if I have 2 AG groups and primary at the same replica (sql instance) at the same time , each AG has for example 20 Databases. is this situation hit this limitation ?

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As I read the passage, you would hit that limit if your transaction spans 33 databases or more.

If you really want to know what happens in that scenario you describe, you would have to set it up to test. But maybe you should first ask yourself, how likely it is that you will need a 33-database transactions that spans two AGs....

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