[英]Linq to SQL grouping with embedded lists causes too many queries
我正在开发一个查询来获取和加入 C# 中的一些 SQL 表,并且在数据集中的分组和枚举方面遇到了一些问题。 我的查询如下。 这为我提供了我正在寻找的格式的数据,但是当我尝试添加枚举列表时花费的时间太长,如下所示。 当我查看引擎盖时,我可以看到它正在执行太多的 SQL 查询。 我想把它变成一个。 使用 LinqPad:
void Main()
{
var nightlyRuns = (from a in LoadTestSummaries
join b in LoadTestTestSummaryData
on a.LoadTestRunId equals b.LoadTestRunId
where a.TargetStack == "LoadEnv" &&
a.TestGuid != null &&
a.StartTime != null &&
a.LoadTestRunId != null
orderby a.StartTime
group new {a, b} by new
{
a.TestGuid,
a.Name,
a.Description,
a.StartTime,
a.Duration,
a.NumAgents,
a.NumHosts,
a.PassFail,
a.ResultsFilePath,
a.Splunk
}
into g
let scenarioStart = g.Min(s => s.a.StartTime) ?? g.Min(s => s.a.DateCreated)
let testCases = g.Select(s => s.b)
orderby scenarioStart
select new
{
TestGuid = g.Key.TestGuid,
ScenarioRun = new
{
Name = g.Key.Name,
Description = g.Key.Description,
StartTime = scenarioStart,
Duration = g.Key.Duration,
NumAgents = g.Key.NumAgents,
NumHosts = g.Key.NumHosts,
Result = g.Key.PassFail,
ResultsFilePath = g.Key.ResultsFilePath,
SplunkLink = g.Key.Splunk,
// PROBLEM: Causes too many queries:
TestRuns = from t in testCases select t.TestCaseId
}
}).ToLookup(g => g.TestGuid, g => g.ScenarioRun);
nightlyRuns["ba593f66-695f-4fd1-99c3-71253a2e4981"].Dump();
}
“TestRuns”行导致过多的查询。 知道我在这里做错了什么吗?
感谢您的任何见解。
测试的艰难答案,但我认为我们可以通过以下方式避免分组和多个查询:( https://msdn.microsoft.com/en-us/library/bb311040.aspx )
var nightlyRuns = (from a in LoadTestSummaries
join b in LoadTestTestSummaryData
on a.LoadTestRunId equals b.LoadTestRunId
where a.TargetStack == "LoadEnv" &&
a.TestGuid != null &&
a.StartTime != null &&
a.LoadTestRunId != null
into testGroup
select new
{
TestGuid = a.TestGuid,
ScenarioRun = new
{
Name = a.TestGuid,
Description = a.Description,
StartTime = a.StartTime ?? a.DateCreated,
Duration = a.Duration,
NumAgents = g.Key.NumAgents,
NumHosts = a.NumHosts,
Result = a.PassFail,
ResultsFilePath = a.ResultsFilePath,
SplunkLink = a.Splunk,
// PROBLEM: Causes too many queries:
TestRuns =testGroup
}
}).OrderBy(x=>x.StartTime).ToLookup(x => x.TestGuid, x => x.ScenarioRun);
nightlyRuns["ba593f66-695f-4fd1-99c3-71253a2e4981"].Dump();
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