Order by before where (ARCH904)

Key dotnet.linq.order-by-before-where · Severity warning · Category linq

Sorting before filtering also sorts rows that will be discarded, doing unnecessary work.

Incorrect

var result = orders
    .OrderBy(o => o.Date)
    .Where(o => o.IsPaid)
    .ToList();

Correct

var result = orders
    .Where(o => o.IsPaid)
    .OrderBy(o => o.Date)
    .ToList();

Fix

Apply Where() first, then OrderBy().