[Lens] Docs for time shift (#102048)

elastic · Jun 17, 2021 · c75f369 · c75f369
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diff --git a/docs/user/dashboard/images/lens_time_shift.png b/docs/user/dashboard/images/lens_time_shift.png
diff --git a/docs/user/dashboard/lens-advanced.asciidoc b/docs/user/dashboard/lens-advanced.asciidoc
@@ -295,6 +295,41 @@ image::images/lens_advanced_5_2.png[Line chart with cumulative sum of orders mad
 
 . Click *Save and return*.
 
+[discrete]
+[[compare-time-ranges]]
+=== Compare time ranges
+
+*Lens* allows you to compare the currently selected time range with historical data using the *Time shift* option.
+
+Time shifts can be used on any metric. The special shift *previous* will show the time window preceding the currently selected one, spanning the same duration.
+For example, if *Last 7 days* is selected in the time filter, *previous* will show data from 14 days ago to 7 days ago.
+
+If multiple time shifts are used in a single chart, a multiple of the date histogram interval should be chosen - otherwise data points might not line up in the chart and empty spots can occur.
+For example, if a daily interval is used, shifting one series by *36h*, and another one by *1d*, is not recommended. In this scenario, either reduce the interval to *12h*, or create two separate charts.
+
+To compare current sales numbers with sales from a week ago, follow these steps: 
+
+. Open *Lens*.
+
+. From the *Chart Type* dropdown, select *Line*.
+
+. From the *Available fields* list, drag and drop *Records* to the visualization builder.
+
+. Copy the *Count of Records* series by dragging it to the empty drop target of the *Vertical axis* dimension group (*Drop a field or click to add*)
+
+. Shift the second *Count of Records* series by one week to do a week-over-week comparison
+
+.. Click the new *Count of Records [1]* dimension
+
+.. Click *Add advanced options* below the field selector
+
+.. Click *Time shift*
+
+.. Click the *1 week* option. You can also define custom shifts by typing amount followed by time unit (like *1w* for a one week shift), then hit enter.
+
+[role="screenshot"]
+image::images/lens_time_shift.png[Line chart with week-over-week sales comparison]
+
 [discrete]
 [[view-customers-over-time-by-continents]]
 === View table of customers by category over time