Metadata Discovery
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
The metadata discovery improvement in SQL Server 2012 (11.x) allows OLE DB Driver for SQL Server applications to ensure that column or parameter metadata returned from the execution of a query is identical to or compatible with the metadata format you specified before you executed the query. You will receive an error if the metadata returned after query execution is not compatible with the metadata format you specified before query execution.
In bcp and IBCPSession and IBCPSession2 interfaces, you can now specify a delayed read (delayed metadata discovery) to avoid metadata discovery for query out operations. This improves performance and eliminates metadata discovery failures.
If you develop an application using OLE DB Driver for SQL Server but connect to a server version earlier than SQL Server 2012 (11.x), metadata discovery functionality will correspond to the version of the server.
Remarks
The following OLE DB member functions have been enhanced in SQL Server 2012 (11.x) to provide improved metadata discovery:
IColumnsInfo::GetColumnInfo
IColumnsRowset::GetColumnsRowset
ICommandWithParameters::GetParameterInfo (see ICommandWithParameters for more information)
You will also see a performance improvement when specifying metadata format using IBCPSession::BCPSetBulkMode
The improved metadata discovery in OLE DB Driver for SQL Server is possible because of the addition of two stored procedures in SQL Server 2012 (11.x):
sp_describe_first_result_set
sp_describe_undeclared_parameters