Analytics: Exploring Table Views

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This article is part of a series, beginning with Analytics Application - Concepts and Metrics Explained

The Analytics Application included with Pulse Services Director offers a unique Table View in the Explore functions, which combines request metrics, connection metrics, and sparkline graphs, all in a single page. It is formed from the results of two separate queries:

• A query for the overall metrics
• A query for the sparkline metrics 

Overall metrics

The Table View shows five metrics in total. These are split by vServers, grouped together by cluster.

• Avg. Connection Duration (ms)
• Avg. Request Duration (ms)
• Throughput (Mbps)
• Connections / second
• Requests / second

As described in Terminology: Transactions, Connections and Requests, each vServer supports a specific protocol which determines whether it produces request-based metrics or connection-based metrics.

As a result of this, each vServer line will show either values in the columns for request-based metrics, orconnection-based metrics, but never both. Unused columns show a '–' symbol. The Throughput metric is an exception to this, as it can be sensibly applied to both connections and requests, and so appears for each vServer. The overall metrics are calculated using the following method:

1. Filter out records outside the time range
2. Apply any further filters (from the Component Filter and/or the Extended Filter)
3. For each transaction, determine:
   Whether it is connection-based or request-based
   The size the transaction in Megabits (Mb):
   -  Add together "vserver bytes in" and "vserver bytes out"
   - Multiply the result by 0.000008 to convert into Megabits.
   
   
4. Aggregate the following results by cluster and vServer:
   - The count of transactions
   - The sum of Megabits (Mb) transferred
   - The average request duration (where applicable)
   - The average connection duration (where applicable)
   
   
5. Take the results from the aggregation stage and:
   For request-based vServers:
    - Calculate requests per second as (transaction count / seconds in full time range)
    - Round average request duration to 0 decimal points
    - Rename to average request duration
   
   

   For connection-based vServers:
   - Calculate connections per second as (transaction count / seconds in full time range)
   - Round average connection duration to 0 decimal points
   - Rename to average connection duration
   
   

   For all vServers:
   - Calculate throughput in Mbps
   - Calculated as (throughput as sum of Mb transferred) / (seconds in full time range)

 
Sparkline metrics

The Table View also shows sparklines in one of the columns. This column is the current user-selected data metric. The data for all the sparklines is generated in one query. The sparkline metrics are calculated in a similar way to timecharts:

1. Generate a request duration field for each analytics record in milliseconds:
   Subtract "timeline.crqs" from "timeline.crse"
   Multiply the result by 1000 to convert into milliseconds
   
   
2. Filter away all records outside the time range.
3. Apply any further filters (from the Component Filter and/or the Extended Filter)
   
   
4. For each transaction:
   

   Determine whether the transaction is connection-based or request-based, and set fields as described below:
   
   

   For connection-based transactions:
   - Record a connection count of 1
   - Make the connection duration equal to the transaction duration
   - Set the request count to 'null'
   - Set the request duration to 'null'
   
   

   For request-based transactions:
   - Set the connection count to 'null'
   - Set the connection duration to 'null'
   - Record a request count of 1
   - Make the request duration equal to the pre-calculated request duration field
   
   

   Calculate the size the transaction in Megabits (Mb):
   - Add together "vserver bytes in" and "vserver bytes out"
   - Multiply the result by 0.000008 to convert into Megabits.

5. For each timebucket, with an additional split by cluster vserver, calculate:
   - Connections per second as (sum of connection counts) / (seconds in the full time range).
   - The average of all connection durations.
   - Requests per second as (sum of request counts) / (seconds in the full time range) .
   - The average of all request durations.
   - Throughput in Mbps is calculated as (sum of transaction size in Mb) / (seconds in the full time range)

Sparkline Scale

It is important to remember that each Sparkline graph is intended to show changes in the selected metric over time on a per-vServer basis, and is notintended for direct vServer to vServer comparison. 

In order to make best use of available vertical browser space, each vServer-specific graph is individually scaled. The following example shows sparklines for vServers in the Avg. Request Duration (ms) column, with values of 5ms, 137ms and 1587ms respectively.

The tallest lines on each graph are the same height; however, if you hover the cursor over each sparkline you can see the exact value. For example, the tallest line on the top graph (which has an average of 5ms) represents a request duration of 12ms:

Similarly, the tallest lines on the bottom graph (which has an average of 1587ms) represents a request duration of ~4000ms.

For direct vServer to vServer comparisons, it is better to use the Line View with a vServer split.

This article is part of a series, beginning with Analytics Application - Concepts and Metrics Explained

Prev: Understanding Time Charts and Metrics

Next: Interpreting Horseshoe and Timeline Charts