SharePoint CSOM C# Load Query with Where Clause Performance

How does SharePoint CSOM handle this block of code?

FileCollection allDocs = libFolder.Files;
clientContext.Load(allDocs, files => files.Where(file => file.Name == "test.docx");
clientContext.ExecuteQuery();

if (allDocs.Count > 0)
{
    File currentDoc = allDocs[0];
    // continue
}

Is the "allDocs" collection fully enumerated, or does the Where clause in the Load parameters pinpoint a single file?

Also, there has to be a better way of retrieving a file by filename in CSOM without the "allDocs[0]" indexed collection selection. How would you do it?

it should pinpoint the single file if using code below:

FileCollection allDocs = libFolder.Files.Where(file => file.Name == "test.docx");
clientContext.LoadQuery(allDocs); // IQueryable
clientContext.ExecuteQuery();
// it should query on server and return only requested items without enumerating 
// whole library
// i think your code does the same, but im not sure here
// i personally prefer using syntax above
// note that im using LoadQuery, but not Load method

// you can select a single item like this without awkward allDocs[0] syntax
var singleDoc = allDocs.SingleOrDefault();
if (singleDoc != null) {
    // do something
}

How would you do it?

Probably CAML Query.