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Histogram Chart

Histogram shows the dispersion of log records over the time period and can be used to drill down into a specific set of log records.

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You can generate charts for the log records, groups and numeric display fields. Select a row to view the range highlighted in the histogram.

The following chart options are to view the group data on the histogram:

Histogram Chart Option Utility

Chart Type

Select from the following types of visualization to view the group data:

  • Bar: The log records are displayed as segmented columns against the time period. This is the default display chart.

  • Marker Only : The size of the log records against the specific time is represented by a marker.

  • Line Without Marker: The size of the log records against the specific time is plotted with the line tracing the number that represents the size.

  • Line With Marker: The size of the log records against the specific time is plotted with the line tracing the marker that represents the size.

  • Line With Area: This is similar to a line chart, but the area between the line and the axis is covered with color. The colored area represents the volume of data.

Show Combined Chart

This option combines all the individual charts into a single chart.
Note

  • You can modify the Height and Width of the charts to optimize the visualization and view multiple charts on one line.

  • When viewing multiple charts, you can deselect the Show Correlated Tooltips check box to show only one tooltip at a time.

  • When using the log scale, the Bar or Line With Marker type of chart is recommended.

Example: For generating a chart for the numeric eval command, let's consider the example query: 

* 
| rename 'Content Size' as sz 
| where sz > 0 
| link 'Log Source' 
| stats avg(sz) as 'Avg Sz', earliest(sz) as FirstSz, latest(sz) as LastSz 
| eval Delta = LastSz - FirstSz 
| eval Rate = Delta / 'Avg Sz'

Here, the log source is the field considered for Group By. The chart is generated for Delta, Rate, and Avg Sz after the computations performed as specified in the eval command. The resulting Line With Area charts for the above fields are displayed as below:


Description of histogram_chart_eval.png follows

Compare Link Metrics Across Time

Use the compare command to compare metrics generated in link analysis to the previous time windows.

Following example query compares the data transfer between two IPs across previous four days by using the compare command: 

'Log Source' = 'OCI VCN Flow Unified Schema Logs'
| eval 'Bytes Transferred' = unit('Content Size Out', byte)
| link Time, 'Source IP', 'Destination IP'
| stats sum('Bytes Transferred') as 'Transfer Size' 
| compare fields = 'Transfer Size' timeshift = -1day count = 4

The resulting histogram chart that indicates the comparison:


histogram chart where the values corresponding to different time shift can be compared

Combine and Stack Histogram Charts

You can combine and stack charts using the Show Combined and Show Stacked options in link.

For example, the following query shows the trend of logs with various values for the Problem Priority field, in a stacked chart: 

*
| link Time, Entity
| addfields
   [ 'Problem Priority' != null  | stats count as Issues ],
   [ 'Problem Priority' = Low    | stats count as 'Issues - Low Priority'    ],
   [ 'Problem Priority' = Medium | stats count as 'Issues - Medium Priority' ],
   [ 'Problem Priority' = High   | stats count as 'Issues - High Priority'   ]
| fields -Issues, -'Issues - Low Priority', -'Issues - Medium Priority', -'Issues - High Priority'

trend of logs with various values for the Problem Priority field in a stacked chart

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