fix(csharp/src/Drivers/Apache/Hive2): Remove unnecessary CloseOperation in Statement.Dispose when query is metadata query

[jackyhu-db]

Motivation

When the client calls HiveServer2Statement to execute metadata query (e.g. GetCatalogsAsync, GetSchemasAsync), it won't set _directResults, which leads to a unnecessary thrift call (CloseOperation) in its HiveServer2Statement.Dispose, this is because it will make a blocking call CloseOperation if _directResults=null (see code here), it introduces 100ms-200ms latency for every metadata call/query

Change

Set HiveServer2Statement._directResults from resp.DirectResult in every metadata API in HiveServer2Statement, thus thrift CloseOperation won't be called in Dispose if metadata query/option returns a successful DirectResult.

Testing

• All the E2E testing on Databricks driver
• PGPerf.exe and saw 200-300ms performance improvement for every query scenario with Databricks

[CurtHagenlocher]

This is definitely not needed for GetCrossReferenceAsForeignTableAsync? Should there be a comment to that effect?

[jackyhu-db]

This is definitely not needed for GetCrossReferenceAsForeignTableAsync? Should there be a comment to that effect?

If we do not set this, CloseOperation will be called if the client calls GetCrossReferenceAsForeignTableAsync

[CurtHagenlocher]

This is definitely not needed for GetCrossReferenceAsForeignTableAsync? Should there be a comment to that effect?

If we do not set this, CloseOperation will be called if the client calls GetCrossReferenceAsForeignTableAsync

Sorry, I didn't word that very well. Every method that calls GetQueryResult was changed except for GetCrossReferenceAsForeignTableAsync so I just wanted to confirm that this is correct.

[jackyhu-db]

This is definitely not needed for GetCrossReferenceAsForeignTableAsync? Should there be a comment to that effect?

If we do not set this, CloseOperation will be called if the client calls GetCrossReferenceAsForeignTableAsync

Sorry, I didn't word that very well. Every method that calls GetQueryResult was changed except for GetCrossReferenceAsForeignTableAsync so I just wanted to confirm that this is correct.

Thanks for catching this. It should be added as well, uploaded a fix.