topic Re: Large number of regular expressions in search field in Splunk Search

Large number of regular expressions in search field

tamnor — Mon, 28 Sep 2020 12:58:58 GMT

I am a new Splunk user and at the moment I am using it to monitor the performance of the web applications of the insurance company that I work for. I want to be able to generate a report that shows the average response time against each web request as well as the number of instances of that request that were submitted for a given time period. A large number of the web requests have dynamic values in them for customer id, policy number, claim id, repair booking etc. I am using regular expressions to filter out the unique info and group the request together. So at the moment I have a search that looks like the following ..

index=arena_repairs_prod responseTime>5000 lodge | rex field=uri_path mode=sed "s/repair\/summary.html\?repairId=[0-9]+/repair\/summary.html?repairId=/" | rex field=uri_path mode=sed ....

So I just keep repeating the regular expressions one after the other in the search field. I can see that my search is going to become quite large.

Is this the best way to create a search like this, or is there someone of saving each of the regular expressions and just referring to them by a variable name?

Any advice would be much appreciated.

Re: Large number of regular expressions in search field

Ayn — Tue, 18 Dec 2012 08:45:17 GMT

It would be better not to mess with the raw data but instead extract the endpoints you're interested in as fields and then group by that. So instead of

 ... | rex field=uri_path mode=sed "s/repair\/summary.html?repairId=[0-9]+/repair\/summary.html?repairId=/"

Couldn't you just check all requests to summary.html?

... | rex field=uri_path "^(?<requestedPage>[^?]+)"

Re: Large number of regular expressions in search field

martin_mueller — Tue, 18 Dec 2012 12:10:47 GMT

There is a way to save regular expressions to have fields extracted automatically each time you search, without cluttering your query. You can use the interactive field extractor, or create extractions/transformations yourself.

IFX how-to: http://www.splunk.com/view/SP-CAAADUY
Field extraction in general: http://docs.splunk.com/Documentation/Splunk/5.0/Knowledge/Aboutfields

Re: Large number of regular expressions in search field

GKC — Tue, 18 Dec 2012 23:59:52 GMT

you might also find this website as a useful tool for regex

http://gskinner.com/RegExr/

Re: Large number of regular expressions in search field

tamnor — Mon, 28 Sep 2020 13:07:02 GMT

Hi. Thanks for the responses. This is no longer a problem as the indexing was changed so that the uri_path is an extracted field so I can group by this rather than the full url with all the dynamic values. There are still some dynamic values in the uri_path but not that many so my queries aren't too long.