topic Re: Can anyone explain how this transaction search for average request execution works? in Splunk Search

Can anyone explain how this transaction search for average request execution works?

prakash007 — Tue, 01 Dec 2015 04:44:55 GMT

Can anyone please explain this search? It's for average request execution:

index=main sourcetype=access_combined OR sourcetype=log4j 
| eval action=substr(uri_path,2) 
| eval action=lower(if(isnull(action),requestType,action)) 
| eval JSESSIONID=if(isnull(JSESSIONID),sessionId,JSESSIONID) 
| transaction threadId, JSESSIONID, action maxspan=1m 
| stats avg(duration) AS Avg_Request_Execution_Time

Re: Can anyone explain how this transaction search for average request execution works?

DMohn — Tue, 01 Dec 2015 09:06:50 GMT

Let's break up this search into its parts

 index=main sourcetype=access_combined OR sourcetype=log4j

pretty straight forward: take the events from the main index, sourcetypes access_combined or log4j

 | eval action=substr(uri_path,2)

create a new field action by extracting a substring out of the field uri_path from the second char

 | eval action=lower(if(isnull(action),requestType,action))

checks if the field action is empty (isnull). If so, action takes the value of the field requestType, otherwise the value of action remains the same. The field value is converted to lower case.

 | eval JSESSIONID=if(isnull(JSESSIONID),sessionId,JSESSIONID)

checks if the field JSESSIONID is null. If so, JSESSIONID takes the value of the field sessionID, otherwise the value of action remains the same.

 | transaction threadId, JSESSIONID, action maxspan=1m

creates a transaction with the fields threadId and JSESSIONID with a maximum duration of 1 minute - that is, checking all events within one minute, where the values of threadId and JSESSIONID are identical, and combining them to one transaction. Check http://docs.splunk.com/Documentation/Splunk/6.3.1/SearchReference/Transaction for more details.

| stats avg(duration) AS Avg_Request_Execution_Time

create a stats table for the average value of duration - which is a field created by the transaction command - and naming this field Avg_Request_Execution_Time.

Any further details needed? Feel free to comment!

Re: Can anyone explain how this transaction search for average request execution works?

woodcock — Tue, 01 Dec 2015 09:08:51 GMT

It is gathering up all events for a web session or jsession by using the transaction command which also calculates a duration field for each session from which an average can be calculated.

Re: Can anyone explain how this transaction search for average request execution works?

prakash007 — Tue, 29 Sep 2020 08:03:53 GMT

Thanks for the explanation...i still have a question..

for the search below, you said it's extracting substring out of uri_path..here're the field values for uri_path.
/viewcart , /updatecart, /updateitem...etc

Is it necessary to extract a substring, if it's how does it work...can you please explain..

| eval action=substr(uri_path,2)
create a new field action by extracting a substring out of the field uri_path from the second char

Re: Can anyone explain how this transaction search for average request execution works?

DMohn — Tue, 05 Jan 2016 10:01:19 GMT

Sorry for the delay ...

As you stated, the values for uri_path all start with a slash char '/' - the substr command just removes the leading slash from the value, so this is (more or less) just a 'cosmetic correction'. Now you are able to search for action=viewcart - which is much nicer than having to search for action="/viewcart"

Re: Can anyone explain how this transaction search for average request execution works?

prakash007 — Tue, 05 Jan 2016 19:17:49 GMT

Got it.. Thanks much..!!