Foreign Data Wrapper (FDW) to connect to a read-only secondary server on SQL Server

[aviadco11]

Issue report

I'm attempting to utilize Foreign Data Wrapper (FDW) to connect to a read-only secondary server on SQL Server. When connecting from a third-party tool, you can simply add the 'read-only' flag, for example, with SQLCMD:
sqlcmd -S "SQL01-AG1-list" -d WideWorldImporters-E -q "SELECT @@ServerName;" -Kreadonly
This can also be achieved using ODBC.
I try to explore if is it possible with tds_fdw ?

Operating system

LINUX / WINDOWS

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Version of tds_fdw

every version : tds_fdw

If you built the package from Git sources, also paste the output of running git log --source -n 1 on your git clone from a console

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Version of PostgreSQL

15.0 +

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Version of FreeTDS

How to get it will depend on your Operating System and how you installes FreeTDS

From a console:

• On RPM based systems: rpm -qa|grep freetds
• On Deb based systems: dpkg -l|grep freetds
• If you built your own binaries from source code, then go to the sources, and run: grep 'AC_INIT' configure.ac

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Logs

Please capture the logs when the error you are reporting is happening, as well as commands with their outputs if you are reporting a problem build or installing

For problems using tds_fdw on PostgreSQL how to do it will depend on your system, but if your PostgreSQL is installed on GNU/Linux, you will want to use tail -f with the log of the PostgreSQL cluster

For MSSQL you will need to use the SQL Server Audit Log

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Sentences, data structures, data

This will depend on the exact problem you are having and data privacy restrictions

However the more data you provide, the more likely we will be able to help

As a bare minimum, you should provide

• The SQL sentence that is failing
• The data structure on the PostgreSQL side and on the MSSQL side

Replace this with the SQL sentences, data structures, etc

[juliogonzalez]

Did you give it a try?

As the README.md file says:

The current version does not yet support JOIN push-down, or write operations.

So it should work, and if that secondary server on SQL Server is read-only, then IMHO there's no risk :-)