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POLinq to SQL query taking forever
 

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  1. POLinq to SQL query taking forever
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    <p>Ok, first I thought I had a problem with how I was querying things. But apparently the problem lies in how linq translates my query to sql.</p> <p>Here's my linq:</p> <pre><code>var items = (from p in ctx.bam_Prestatie_AllInstances join q in ctx.bam_Zending_AllRelationships on p.ActivityID equals q.ReferenceData join r in ctx.bam_Zending_AllInstances on q.ActivityID equals r.ActivityID orderby p.LastModified descending where r.PrestatieOntvangen &gt;= vanaf &amp;&amp; r.PrestatieOntvangen &lt;= tm select new Data.BAMPrestatieInstance { Aanvaard = p.PrestatieAanvaard, Contactnummer = r.ContactNr, Identificatie = p.Identificatie, Foutmelding = ((p.Foutmelding == "" || p.Foutmelding == null) &amp;&amp; p.PrestatieAanvaard == null) ? "De prestatie is bezig met verwerkt te worden." : p.Foutmelding.Replace("\r\n", " "), Ontvangen = p.PrestatieZendingOntvangen, Uitvoerdatum = p.Uitvoerdatum.Replace('-', '/'), Zender = r.Zender, PrestatieCode = p.PrestatieCode, ZendingsNr = r.Zendingnummer.ToString(), GroepsAanvaarding = r.Identificatie }).Take(100); </code></pre> <p>Which gets translated in:</p> <pre><code>SELECT TOP (100) [t3].[Zender], [t3].[ContactNr] AS [Contactnummer], [t3].[Identificatie], [t3].[value] AS [Uitvoerdatum], [t3].[PrestatieZendingOntvangen] AS [Ontvangen], [t3].[PrestatieAanvaard] AS [Aanvaard], [t3].[value2] AS [Foutmelding], [t3].[PrestatieCode], [t3].[value3] AS [ZendingsNr], [t3].[Identificatie2] AS [GroepsAanvaarding] FROM ( SELECT [t2].[Zender], [t2].[ContactNr], [t0].[Identificatie], REPLACE([t0].[Uitvoerdatum], @p0, @p1) AS [value], [t0].[PrestatieZendingOntvangen], [t0].[PrestatieAanvaard], (CASE WHEN (([t0].[Foutmelding] = @p2) OR ([t0].[Foutmelding] IS NULL)) AND ([t0].[PrestatieAanvaard] IS NULL) THEN CONVERT(NVarChar(3800),@p3) ELSE REPLACE([t0].[Foutmelding], @p4, @p5) END) AS [value2], [t0].[PrestatieCode], CONVERT(NVarChar,[t2].[Zendingnummer]) AS [value3], [t2].[Identificatie] AS [Identificatie2], [t2].[PrestatieOntvangen], [t0].[LastModified] FROM [dbo].[bam_Prestatie_AllInstances] AS [t0] INNER JOIN [dbo].[bam_Zending_AllRelationships] AS [t1] ON [t0].[ActivityID] = [t1].[ReferenceData] INNER JOIN [dbo].[bam_Zending_AllInstances] AS [t2] ON [t1].[ActivityID] = [t2].[ActivityID] ) AS [t3] WHERE ([t3].[PrestatieOntvangen] &gt;= @p6) AND ([t3].[PrestatieOntvangen] &lt;= @p7) ORDER BY [t3].[LastModified] DESC </code></pre> <p>As you can see, first it selects EVERYTHING and then it takes the top 100 and does the where. Why is this? Why can't it directly do the top 100, I think the problem why my queries run so long is because of this. Is there a better way to construct my linq query then?</p> <p>Thanks</p>
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    1. USNick Craver
    1. USWtFudgE
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    1. COFunny thing I noticed btw, if i REMOVE the TOP 100 from the query it takes 4 seconds and shows me 22000 items, if i set the top 100 back again, it takes 55seconds. I think it has something to do with copying it to a temporary table or something
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      1. POLinq to SQL query taking forever
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    2. COI temporarily fixed my problem by just selecting all and looping through the first 100 lines, it goes a lot faster but I'm not that pleased :(
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