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Editorial Team
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Asked: 2026-05-12T21:32:21+00:00

In our database we have a table with more then 100000 entries but most

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In our database we have a table with more then 100000 entries but most of the time we only need a part of it. We do this with a very simple query.

items.AddRange(from i in this
    where i.ResultID == resultID && i.AgentID == parentAgentID
    orderby i.ChangeDate descending
    select i);

After this Query we get a List with up to 500 items. But even from this result we only need the newest and following item. My coworker did this very simple with:

items[0];
items[1];

Works fine since the query result is already ordered by date. But the overall performance is very poor. Takes some seconds even.

My idea was to add a .Take(2) at the end of the query but my coworker said this will make no difference.

items.AddRange((from i in resultlist
    where i.ResultID == resultID && i.AgentID == parentAgentID
    orderby i.ChangeDate descending
    select i).Take(2));

We haven’t tried this yet and we are still looking for additional ways to speed things up. But database programming is not our strong side and any advice would be great.

Maybe we can even make some adjustments to the database itself? We use a SQL Compact Database.

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1 Answer

  1. Editorial Team

    Using Take(2) should indeed make a difference, if the optimiser is reasonably smart, and particularly if the ChangeDate column is indexed. (I don’t know how much optimization SQL Compact edition does, but I’d still expect limiting the results to be helpful.)

    However, you shouldn’t trust me or anyone else to say so. See what query is being generated in each case, and run it against the SQL profiler. See what the execution plan is. Measure the performance with various samples. Measure, measure, measure.

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