== Why is this an issue?

The ``++SystemModStamp++`` and ``++LastModifiedDate++`` are similar in that they store last modification dates of a record. The main difference is that ``++LastModifiedDate++`` is only updated when users update a record, not when automated system do it.


This means that 'LastModifiedDate +<=+ SystemModStamp' but it is not possible to have 'LastModifiedDate > SystemModStamp'


The ``++SystemModStamp++`` field is indexed, whereas ``++LastModifiedDate++`` is not. In most case when an SOQL query filters on ``++LastModifiedDate++``, the index of ``++SystemModStamp++`` will be used instead. This however does not apply when the filter is of the form ``++where LastModifiedDate < :mydate++`` because ``++SystemModStamp++`` can be greater than ``++LastModifiedDate++``.


This rule raises an issue when an SOQL query has a ``++where++`` filter with a condition of the form ``++LastModifiedDate < :mydate++`` or ``++LastModifiedDate <= :mydate++``.


=== Noncompliant code example

[source,apex]
----
[Select Id from Case where LastModifiedDate < :mydate]; // Noncompliant
[Select Id from Case where LastModifiedDate <= :mydate]; // Noncompliant
----


== Resources

* https://developer.salesforce.com/blogs/engineering/2014/11/force-com-soql-performance-tips-systemmodstamp-vs-lastmodifieddate-2.html[Force.com SOQL Performance Tips: LastModifiedDate vs SystemModStamp]

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Replace this use of LastModifiedDate with SystemModStamp.


endif::env-github,rspecator-view[]