Brian Hartsock's Blog

public void Foo(IEnumerable<string> strings)
{
	IEnumberable<string> stringsInDb = strings.Where(s => this.QueryTheDbAndTakeALongTime(s));
 
	foreach(string str in stringsInDb)
	{
		//Where clause in LINQ is actually executed 
	}
 
	foreach(string str in stringsInDb)
	{
		//Where clause in LINQ is actually executed  AGAIN
	}
}

IEnumberable<string> stringsInDb = strings.Where(s => this.QueryTheDbAndTakeALongTime(s)).ToList();