Please have a look at the following 2 snippets:

var query = _ctx.Notes.Where(...);    
var searchLower = searchTerms.ToLower();
query = query.Where(a => a.Comment.ToLower().Contains(searchLower))


var query = _ctx.Notes.Where(...);        
query = query.Where(a => a.Comment.ToLower().Contains(searchTerms.ToLower()))

Is there any peformance increase by converting the search terms before carrying out the LINQ query?


1 Answer 1


Instead of Contains(), use IndexOf() which takes a comparer:

var query = _ctx.Notes.Where(...);        
query = query.Where(a => a.Comment.IndexOf(searchTerms, StringComparison.OrdinalIgnoreCase) >= 0)
  • \$\begingroup\$ I think it should be >= 0 \$\endgroup\$ Dec 21, 2011 at 16:47
  • \$\begingroup\$ Is this actually quicker against an SQL database? \$\endgroup\$
    – jaffa
    Dec 21, 2011 at 17:07
  • \$\begingroup\$ @jaffa: your best bet for speed against the database is to have a case-insensitive column with Latin1_General_CS_AS (or appropriate) and run that contains in a stored proc. \$\endgroup\$ Dec 21, 2011 at 17:16

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