Cause

Data is queried within an iteration (while, do-while, foreach, for) through IQuerySession (Load, LoadAsync, LoadMany, LoadManyAsync, Query, QueryAsync) or IBatchedQuery (Load, LoadMany, Query).

Reason for rule

Queries within an iteration can indicate Select N+1 issues (see, What is N+1 SELECT query issue?). This rule aids in locating such sites, supporting manual code review of violations.

How to fix violations

To fix a violation of this rule, joins can be used to load related data. Otherwise remodeling relations in a more document-oriented fashion might be considered.

Examples

Violates

var dict = new Dictionary<Guid, User>();

var issues = session.Query<Issue>();

// Each issue generates an additional query
foreach (var i in issues)
{
	var user = session.Load<User>(i.AssigneeId.Value);
	dict.Add(user.Id, user);
}

Does not violate

// Issues with assignees are fetched in one round-trip.
var dict = new Dictionary<Guid, User>();

session.Query<Issue>().Include(x => x.AssigneeId, dict).ToArray();