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Sumo Logic

backshift

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The backshift operator compares values as they change over time. backshift can be used with rollingstd, smooth, or any other operators whose results could be affected by spikes of data (where a spike could possibly throw off future results).

It's important to note that backshift doesn't automatically add timeslices, nor does it do any sorting. You can manually add other operators in the query to add timeslices, for example, and any kind of sorting you'd like to include. To add time-series analysis, add _timeslice | ... | sort + _timeslice before the backshift operator in the query.

Syntax

  • backshift <field> [, shift_length]

Rules

  • An alias for backshift is optional. When an alias is not provided, _backshift is the default alias.
  • Specified fields must contain numeric values.
  • To add a query that includes a backshift operator to a dashboard, you must add a group by function before the backshift operator.
  • The default window length (shift_length) is 10.
  • The maximum window length is 1000.

Example

Use backshift to see the difference of fields between time points.

Running a query like this:

_sourcecategory=Labs/Apache/Access 
| timeslice by 1m 
| count by _timeslice 
| sort + _timeslice 
| backshift _count,10 as size

produces results like:

backshift_new_table.png

Then you can visualize the results as an area chart.

backshift_new_graph.png