LINQ - Is Contains much faster than Equals(==)?
Multi tool use
LINQ - Is Contains much faster than Equals(==)?
I have a query that returns a large amount of data based on the ID I provide.
results = (from x in database
where x.ID == MY_SELECTED_ID
select x).ToList();
It took around 40 seconds to execute that query.
Then I created another query:
results = (from x in database
where
(MyIDList.Contains(SqlFunctions.StringConvert((double)x.ID).Trim())
select x).ToList();
It took around 10-15 seconds to execute that query.
So, is Contains faster when it has to do with large amount of data?
Thanks
You can see what query is generated. There is a way to log them in the debug window. Compare them..
– J. van Langen
Jun 8 at 10:50
Welcome to SO! Take the queries that are generated and run them on the DBMS after clearing the cache.
– Sefe
Jun 8 at 10:59
In linq to sql, c#'s
== equals to = in sql and c#'s Contains() method translates into sql's IN.– SeM
Jun 8 at 11:22
==
=
Contains()
IN
at least for entity framework for .net core I have experienced the opposite where .Contains was evaluated in code and thus much slower. My advice is to open a profiler if it is Sql Server and see what is actually generated.
– Thomas Koelle
Jun 8 at 11:25
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Measure that again, several times and in different orders. This looks like the result of caching. Benchmarking is not easy. You have to know all factors involved.
– bommelding
Jun 8 at 10:46