CODEWITHSUNDEEP
c#.netlinq
Night Walker
Night Walker

Reputation: 21280

How I can Optimize this linq query

Is there some way to optimize this query ?

_alternatives.Cast<AlternativePartName>()
                                .Where(alt => original.ToLower() == alt.CompName)
                                .Select(alt => alt.AltCompName).ToList();

I am profiling my application and this code is one of the bottlenecks 196 ms but it executed a lot of times.

Upvotes: 1

Views: 108

Answers (6)

fubo
fubo

Reputation: 46005

You should try to use more of your cores with .AsParallel() - this could be a improvement at huge lists with long strings

string lower = original.ToLower();
_alternatives.Cast<AlternativePartName>()
              .AsParallel()
              .Where(alt =>  lower == alt.CompName)
              .Select(alt => alt.AltCompName)

Upvotes: 2

WhileTrueSleep
WhileTrueSleep

Reputation: 1534

To call orignal.ToLower() only once won't change anything real in performance.

Try to use e.g. Parallel LINQ to get the result faster if you got enough CPU-Power left.

Upvotes: 0

Thomas Koelle
Thomas Koelle

Reputation: 3752

I am not so good with the dot syntax, but this

.Select(alt => alt.AltCompName)

combined with this

_alternatives.Cast<AlternativePartName>()

Could be achived with the select directly making the AlternativPartName

select new AlternativePartName(){...}

Upvotes: -2

Euphoric
Euphoric

Reputation: 12859

Using correct data structures is best way to increse performance. In your case, it would be better if you used dictionary with CompName being the key and list of AltCompNames being the item. The lookup would be blazing fast, because there would be no iteration, just single lookup. And keeping such simple structure up-to-date with adding and removing items should not be a huge problem.

Upvotes: 0

Sidharth Panwar
Sidharth Panwar

Reputation: 4654

I'm assuming that "original" and "CompName" are strings. If yes, then you should do the following: 

_alternatives.Cast<AlternativePartName>()
                                .Where(alt => String.Equals(original, alt.CompName, StringComparison.OrdinalIgnoreCase))
                                .Select(alt => alt.AltCompName).ToList();

Upvotes: 0

Selman Gen&#231;
Selman Gen&#231;

Reputation: 101742

Instead of calling ToLower for each item, call it only once:

var lower = original.ToLower();

_alternatives.Cast<AlternativePartName>()
              .Where(alt =>  lower == alt.CompName)
              .Select(alt => alt.AltCompName).ToList();

Upvotes: 5

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