avoid some allocations when opening a connection

[ErikEJ]

fixes #3363

[Copilot]

Pull Request Overview

This PR reduces runtime allocations by pre-building arrays of Azure SQL endpoint strings and refactoring the IsEndpoint helper to use these arrays instead of concatenating prefixes on each check.

• Introduces s_azureSqlServerOnDemandEndpoints for on-demand endpoints.
• Changes IsEndpoint to accept a string[] of endpoints.
• Updates calls in IsAzureSynapseOnDemandEndpoint and IsAzureSqlServerEndpoint to use the new arrays.

Comments suppressed due to low confidence (1)

src/Microsoft.Data.SqlClient/src/Microsoft/Data/Common/AdapterUtil.cs:781

• Add unit tests covering each value in s_azureSqlServerOnDemandEndpoints to verify that IsAzureSynapseOnDemandEndpoint correctly recognizes all intended on-demand endpoints.

internal static readonly string[] s_azureSqlServerOnDemandEndpoints = { ONDEMAND_PREFIX + AZURE_SQL,

[paulmedynski]

Great efficiency win. Just a couple of comments.

[ErikEJ]

@paulmedynski Comments addressed

[paulmedynski]

Looks great!

[ErikEJ]

Thanks @vonzshik !

@paulmedynski Possible to get CI running?

[paulmedynski]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.39%. Comparing base (6d2473d) to head (3953e73).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3364      +/-   ##
==========================================
- Coverage   65.10%   61.39%   -3.72%     
==========================================
  Files         300      294       -6     
  Lines       65376    65071     -305     
==========================================
- Hits        42565    39949    -2616     
- Misses      22811    25122    +2311     

Flag	Coverage Δ
addons	?
netcore	66.55% <100.00%> (-1.77%)	⬇️
netfx	59.66% <100.00%> (-6.68%)	⬇️

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[ErikEJ]

@cheenamalhotra @paulmedynski PR updated

[cheenamalhotra]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).

[Wraith2]

some of the failures look real:
https://sqlclientdrivers.visualstudio.com/public/_build/results?buildId=115962&view=logs&j=7d189a9a-61b9-5bcd-ada4-ec4f49fc1287&t=c8db3b6e-0f82-5968-8bc0-30e90fe1961e&l=343

[ErikEJ]

@Wraith2 Thanks, tests (and bugs) fixed.
@edwardneal PR updated

[ErikEJ]

@cheenamalhotra @paulmedynski Could you please help with CI?

[cheenamalhotra]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 2 pipeline(s).