Searching huge Lists

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Hi,

I am using a list of 2,000,000 items and i am having to search it for individual items. This is taking me 5 minutes+. Currently using this Code:

C#

List<MyType> results = GetList();

MyType item = results.Find(item => item.name == "test");

Obviously this speed is unacceptable, I am just wondering what i can do to improve this.

What would be the best way to store/search this data?

Thanks
Carl

Posted 29-Sep-14 6:27am

Carl Mailey

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CHill60 29-Sep-14 12:47pm

Why not store the data on a database and just query for the item you want?

Sergey Alexandrovich Kryukov 29-Sep-14 12:52pm

There are many ways to accelerate the search using some redundant data. But to advise, I would need to know the purpose of all that. Are there any unique properties of an item? And so on...
—SA

2 solutions

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SteveyJDay · Answer 1 · 2014-09-29T06:38:00

Solution 1

Change it to a for each loop. In the speed test I have done LINQ was always the slowest by a large margin.

C#

foreach (MyType item in results) {
	if (string.Compare(item.name, "test", true) == 0) {
		//Do Something.
	}
}

Posted 29-Sep-14 6:38am

SteveyJDay

Comments

Maciej Los 29-Sep-14 14:18pm

Are you sure, that loop is faster then LINQ? Based on my experience, linq is really fast.

Maciej Los · Answer 2 · 2014-09-29T08:22:00

Solution 2

I believe it depends on many factors...

There are few ways to Increase LINQ Query Performance[^]

Posted 29-Sep-14 8:22am

Maciej Los