Linq-To-SQL Multiple Trips to the Database

问题

I'm trying to make my Linq-to-SQL query more efficient by including child properties in one trip to the DB. I started by trying various linq queries to accomplish this. The queries were getting complex, so I tried the LoadWith() option:

The constructor of my DAL class sets the LoadWith() settings:

public TrackerJobData()
{
    dataLoadOptions = new DataLoadOptions();

    dataLoadOptions.LoadWith<TrackerJobRecord>(x => x.SpecBarcodeRecords);
    dataLoadOptions.LoadWith<TrackerJobRecord>(x => x.TrackerJobEquipmentTriggerRecords);
    dataLoadOptions.LoadWith<TrackerJobRecord>(x => x.EtaRecord);

    this.Database.LoadOptions = dataLoadOptions;
}

And here is the query I'm using:

public TrackerJob GetItem(int trackerJobId)
{
    TrackerJobRecord record =
        (from trackerJob in this.Database.TrackerJobRecords
         where trackerJob.TrackerJobId == trackerJobId
         select trackerJob).FirstOrDefault();

    return record.Map();
}

When I debug and F10 on just the linq query (not the return), I get this output in SQL Profiler:

Pardon my ignorance of SQL Profiler, but do the three highlighted lines mean there were three round trips from the client (my code) to the server? If so, why? Will SQL Server ever execute multiple sp_executesql calls in one trip?

And since I thought LoadWith() would eliminate multiple calls, what am I doing incorrectly?

EDIT

Here are the three statements within SQL Profiler:

exec sp_executesql N'SELECT TOP (1) [t0].[TrackerJobId], [t0].[Name], [t0].[EtaId], [t0].[SamplingProcessorTypeId], [t0].[Description], [t0].[LastModifiedUser], [t0].[LastModifiedTime], [t0].[VersionNumber], [t0].[Active], [t0].[Archived], [t1].[EtaId] AS [EtaId2], [t1].[EtaNumber], [t1].[Title], [t1].[State], [t1].[DateInitialized], [t1].[EtaOriginatorId], [t1].[Quantity], [t1].[Ehs], [t1].[Ship], [t1].[InternalUse], [t1].[DateClosed], [t1].[ExperimentId], [t1].[Disposition], [t1].[TestType], [t1].[LastModifiedUser] AS [LastModifiedUser2], [t1].[LastModifiedTime] AS [LastModifiedTime2], [t1].[VersionNumber] AS [VersionNumber2]
FROM [AutoTracker].[TrackerJob] AS [t0]
INNER JOIN [Global].[Eta] AS [t1] ON [t1].[EtaId] = [t0].[EtaId]
WHERE [t0].[TrackerJobId] = @p0',N'@p0 int',@p0=17

exec sp_executesql N'SELECT [t0].[SpecBarcodeId], [t0].[TrackerJobId], [t0].[EquipmentId], [t0].[StartTime], [t0].[EndTime], [t0].[LastModifiedUser], [t0].[LastModifiedTime], [t0].[VersionNumber]
FROM [AutoTracker].[SpecBarcode] AS [t0]
WHERE [t0].[TrackerJobId] = @x1',N'@x1 int',@x1=17

exec sp_executesql N'SELECT [t0].[TrackerJobId], [t0].[EquipmentId], [t0].[LastModifiedUser], [t0].[LastModifiedTime], [t0].[VersionNumber]
FROM [AutoTracker].[TrackerJobEquipmentTrigger] AS [t0]
WHERE [t0].[TrackerJobId] = @x1',N'@x1 int',@x1=17

回答1:

Linq-2-sql LoadWith does not support multiple 1:N relationships.

http://weblogs.asp.net/zeeshanhirani/archive/2008/08/11/constraints-with-loadwith-when-loading-multiple-1-n-relationships.aspx

Linq2SQl eager load with multiple DataLoadOptions

回答2:

Each of those SQL Profiler calls represents a single roundtrip from client to DB server instance. SQL Server does support returning data sets in a single roundtrip, but I'm not sure how you would do that with LINQ to SQL.

来源：https://stackoverflow.com/questions/11869659/linq-to-sql-multiple-trips-to-the-database

标签

sql-server

linq-to-sql

sql-server-profiler