Development KongFu

The (martial) art of programming

Better Searches In LogEntries

17 July 2013

Just had a great talk with the guys from LogEntries. We were talking about some major improvements they are about to make and I wanted to share some thoughts. One thing that came up was the ability to make more complex searches on your logs.

LogEntries Search Engine

LogEntries search engine uses Reg-ex to filter the wanted results. It is great and offers some flexibility, but if you want more complex queries, well, you have to dig deeply into proper Reg-ex syntax. I do many searches and always wanted some more power in my hands to get more accurate results. So if you are a log addict like me, you are gonna love these new Search features in Logentries!

Some Tips About Logging

Logging is good. Log everything.

Once you do it you get tons of logs and there are 2 main things a log line should deliver:

  • Be readable (for humans or machines, depends on who or what will read it)
  • Be easy to search

Now, it is a good practice to adopt some patterns across your organization when it comes to logging. Here are mine:

  • Give each line a topic that suggests whats it about. Use brackets (like [some term]) to make searches more simple.
  • Use key value pairs inside the log line. You can use JSON objects or just key=value patterns.
  • Decide which keys are a most on all logs, such as “username”, “action”, “context”, “latency” and so on.
  • Add more data freely but in the same key value format.

For example, consider a log line like this one:

2013-06-21 09:31:30 [Stock] username=john action=buy stockName=goog sucess=true

This is all fair and square, and it gives me great visibility and search capabilities, but sometimes I need to see 2 searches at the same view.

Introducing AND OR NOT Filters

Though Regex supports AND OR NOT filters, I couldn’t wrap my head around it and make it work easily on LogEntries. Now we can easily use AND, OR, and NOT when searching in Logentries: Lets say you want to search for search-term A and B (Make sure the conditions are capitalized.):

[A] AND [B]

A or B

[A] OR [B]

A and not B

[A] NOT [B]

BTW, you can use multiple AND OR NOT in the search query.

Free Text Searches

Many times you need to make partial matches, like free text search. For example, consider a log line like this one:

2013-06-21 09:31:30 [Stock] username=john action=buy stockName=goog sucess=true

If i would like to search all stock buy actions I can use this:

[Stock] AND /action=buy

The / stands for partial search. Basically it means you treat each search term as a standalone search and combine it with the conditions.


Logging is one of the foundations of good programming. We need to do it well and have a good set of tools to analyze them. This improvement is pretty awesome IMHO and answers a real need in the developer’s life.

Happy logging!

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