Automatically adjust the default ConnectRetryCount against OnDemand endpoints

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlConnection.cs

@@ -412,9 +412,15 @@ private void CacheConnectionStringProperties()
  if (connString != null)
  {
  _connectRetryCount = connString.ConnectRetryCount;
+ // For Azure Synapse ondemand connections, set _connectRetryCount to 5 instead of 1 to greatly improve recovery
+ // success rate. Note: Synapse should be detected first as it could be detected as a regular Azure SQL DB endpoint.
+ if (_connectRetryCount == 1 && ADP.IsAzureSynapseOnDemandEndpoint(connString.DataSource))
+ {
+ _connectRetryCount = 5;
+ }
  // For Azure SQL connection, set _connectRetryCount to 2 instead of 1 will greatly improve recovery
- //  success rate
- if (_connectRetryCount == 1 && ADP.IsAzureSqlServerEndpoint(connString.DataSource))
+ // success rate
+ else if (_connectRetryCount == 1 && ADP.IsAzureSqlServerEndpoint(connString.DataSource))
  {
  _connectRetryCount = 2;
  }

src/Microsoft.Data.SqlClient/netfx/src/Microsoft/Data/SqlClient/SqlConnection.cs

@@ -432,9 +432,15 @@ private void CacheConnectionStringProperties()
  if (connString != null)
  {
  _connectRetryCount = connString.ConnectRetryCount;
+ // For Azure Synapse ondemand connections, set _connectRetryCount to 5 instead of 1 to greatly improve recovery
+ // success rate. Note: Synapse should be detected first as it could be detected as a regular Azure SQL DB endpoint.
+ if (_connectRetryCount == 1 && ADP.IsAzureSynapseOnDemandEndpoint(connString.DataSource))
+ {
+ _connectRetryCount = 5;
+ }
  // For Azure SQL connection, set _connectRetryCount to 2 instead of 1 will greatly improve recovery
- //  success rate
- if (_connectRetryCount == 1 && ADP.IsAzureSqlServerEndpoint(connString.DataSource))
+ // success rate
+ else if (_connectRetryCount == 1 && ADP.IsAzureSqlServerEndpoint(connString.DataSource))
  {
  _connectRetryCount = 2;
  }

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

@@ -686,13 +686,26 @@ internal static Version GetAssemblyVersion()
  }
 
 
+ private const string ONDEMAND_PREFIX = "-ondemand";
+ private const string AZURE_SYNAPSE = "-ondemand.sql.azuresynapse.";
+
+ internal static bool IsAzureSynapseOnDemandEndpoint(string dataSource)
+ {
+ return IsEndpoint(dataSource, ONDEMAND_PREFIX) || dataSource.Contains(AZURE_SYNAPSE);
+ }
+
  internal static readonly string[] s_azureSqlServerEndpoints = { StringsHelper.GetString(Strings.AZURESQL_GenericEndpoint),
  StringsHelper.GetString(Strings.AZURESQL_GermanEndpoint),
  StringsHelper.GetString(Strings.AZURESQL_UsGovEndpoint),
  StringsHelper.GetString(Strings.AZURESQL_ChinaEndpoint)};
 
- // This method assumes dataSource parameter is in TCP connection string format.
  internal static bool IsAzureSqlServerEndpoint(string dataSource)
+ {
+ return IsEndpoint(dataSource, null);
+ }
+
+ // This method assumes dataSource parameter is in TCP connection string format.
+ private static bool IsEndpoint(string dataSource, string prefix)
  {
  int length = dataSource.Length;
  // remove server port
@@ -715,10 +728,10 @@ internal static bool IsAzureSqlServerEndpoint(string dataSource)
  length -= 1;
  }
 
- // check if servername end with any azure endpoints
+ // check if servername ends with any endpoints
  for (int index = 0; index < s_azureSqlServerEndpoints.Length; index++)
  {
- string endpoint = s_azureSqlServerEndpoints[index];
+ string endpoint = string.IsNullOrEmpty(prefix) ? s_azureSqlServerEndpoints[index] : prefix + s_azureSqlServerEndpoints[index];
  if (length > endpoint.Length)
  {
  if (string.Compare(dataSource, length - endpoint.Length, endpoint, 0, endpoint.Length, StringComparison.OrdinalIgnoreCase) == 0)

src/Microsoft.Data.SqlClient/tests/FunctionalTests/SqlConnectionTest.cs

@@ -6,6 +6,7 @@
 using System.Data;
 using System.Collections.Generic;
 using Xunit;
+using System.Reflection;
 
 namespace Microsoft.Data.SqlClient.Tests
 {
@@ -1031,5 +1032,34 @@ public void ConnectionString_IPAddressPreference_Invalid(string value)
  Assert.Contains("'ip address preference'", ex.Message, StringComparison.OrdinalIgnoreCase);
  Assert.Null(ex.ParamName);
  }
+
+ [Fact]
+ public void ConnectionRetryForNonAzureEndpoints()
+ {
+ SqlConnection cn = new SqlConnection("Data Source = someserver");
+ FieldInfo field = typeof(SqlConnection).GetField("_connectRetryCount", BindingFlags.Instance | BindingFlags.NonPublic);
+ Assert.NotNull(field.GetValue(cn));
+ Assert.Equal(1, (int)field.GetValue(cn));
+ }
+
+ [Fact]
+ public void ConnectionRetryForAzureDbEndpoints()
+ {
+ SqlConnection cn = new SqlConnection("Data Source = someserver.database.windows.net");
+ FieldInfo field = typeof(SqlConnection).GetField("_connectRetryCount", BindingFlags.Instance | BindingFlags.NonPublic);
+ Assert.NotNull(field.GetValue(cn));
+ Assert.Equal(2, (int)field.GetValue(cn));
+ }
+
+ [Theory]
+ [InlineData("myserver-ondemand.sql.azuresynapse.net")]
+ [InlineData("someserver-ondemand.database.windows.net")]
+ public void ConnectionRetryForAzureOnDemandEndpoints(string serverName)
+ {
+ SqlConnection cn = new SqlConnection($"Data Source = {serverName}");
+ FieldInfo field = typeof(SqlConnection).GetField("_connectRetryCount", BindingFlags.Instance | BindingFlags.NonPublic);
+ Assert.NotNull(field.GetValue(cn));
+ Assert.Equal(5, (int)field.GetValue(cn));
+ }
  }
 }