SqlBulkCopy: Add hooks to enable retry strategies on batches

[jamescrowley]

If SqlBulkCopy encounters any kind of exception as it inserts rows into a table, it fails the entire job.

In some scenarios, certain errors might be appropriate to retry - for instance, a deadlock or timeout. While this might be unlikely when doing bulk inserts to a staging table, it is much more likely if the table is also shared by a web application, for instance.

For this reason, until now we've instead used Table Valued Parameters.

It would be helpful though if SqlBulkCopy gave us a mechanism to apply a retry strategy as appropriate.

If this isn't the appropriate place to post suggestions like this, let me know. If there was interest in the above, I would happily investigate the feasibility of this further.

[divega]

As recently announced in the .NET Blog, focus on new SqlClient features an improvements is moving to the new Microsoft.Data.SqlClient package. For this reason, we are moving this issue to the new repo at https://github.com/dotnet/SqlClient. We will still use https://github.com/dotnet/corefx to track issues on other providers like System.Data.Odbc and System.Data.OleDB, and general ADO.NET and .NET data access issues.