Introduce (Oracle) optimizer hints (on select )

Oracle allows adding optimizer hint comments on selects that influence the execution plan of the query. With linq2db we can only add queryhints that get appended to the query but don’t help in case of an Oracle DB. I’d like to propose a feature that would look like this.

var result = db.TableName
   .Where(foo => foo.bar = "baz")
   .SelectWithHint("/* +NO_INDEX(TableName_bar) */", foo => foo.bar ).ToList();

this would create SQL like that:

SELECT /* +NO_INDEX(TableName_bar) */ bar  FROM foo WHERE bar = "baz";

Right now i don’t see that this is possible. In case of an convoluted legacy DB this Oracle feature is essential. Here are some more infos to Oracle query hints: https://docs.oracle.com/cd/B12037_01/server.101/b10752/hintsref.htm

[MaceWindu]

Yes, this is definitely one of features we want to implement. It will need some research to gather information about hints in all databases we support, to design and implement proper API, so it will take some time. I will add it to 3.0 roadmap

[sdanyliv]

Try to override ExecuteReader and ExecuteReaderAsync in DataConnection and correct CommandText.