I have an 2 EF entity defined as:
public class Event
{
public DateTime Created { get; set; }
public string Id { get; set; }
public bool Public { get; set; }
public EventType Type { get; set; }
public virtual ICollection<Note> Notes { get; set; }
}
public class Note
{
public string EventId { get; set; } // Link to parent event
public int Id { get; set; }
public string Text { get; set; }
public virtual Event Event { get; set; }
}
When accessing the Notes
collection in Event
, a SQL query is constructed in the form:
exec sp_executesql N'SELECT
[Extent1].[Id] AS [Id],
[Extent1].[EventId] AS [EventId],
[Extent1].[Text] AS [Text]
FROM [dbo].[Notes] AS [Extent1]
WHERE [Extent1].[EventId] = @EntityKeyValue1',
N'@EntityKeyValue1 nvarchar(128)',
@EntityKeyValue1=N'N5427961'
This query, given the data size and indexing used required in excess of 3000 reads. This seemed a bit much given the tables have sufficient indexing. Query analyser had no suggestions to speed the query up.
I then discovered if I changed the datatype being used in the SQL bind from nvarchar(128)
to varchar(33)
, which matches exactly the column type of EventId
in the DB table, the query now only needed 8 reads.
Is this simply a case of me needing to use DataAnnotations to tell EF what the data types in SQL these fields are? or is something else happening here?
I found the way to most easily get the desired effect was:
modelBuilder.Entity<Event>().Property(x => x.Id).IsUnicode(false).HasMaxLength(33);
The other suggested method using annotation did not work and resulted in nvarchar
still being used.
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