Log Parser is a tool that has been around for quite some time (almost six years, in fact).  I can’t really do any better than the description on the official download page, so here it is: “Log parser is a powerful, versatile tool that provides universal query access to text-based data such as log files, XML files and CSV files, as well as key data sources on the Windows operating system such as the Event Log, the Registry, the file system, and Active Directory”.  

Log Parser is a command line (yes, command line!) tool that uses a SQL dialect to extract information from data sources.  In particular, I have found it to be invaluable for extracting information from the web server logs of the sites that I manage and develop.

First, about that SQL syntax Log Parser uses to query the data sources… many developers seem to have a natural aversion to SQL.  In addition, many new data access frameworks attempt to abstract SQL away from the developer.  However, I have always found SQL easy to work with and believe it to be an essential tool that every developer should at least have a working knowledge of.   For Log Parser, all that is necessary is a basic understanding of the core SQL SELECT statement, as implemented within Microsoft’s SQL Server (that is, T-SQL).  That means you should be familiar with the following elements of a SELECT statement: TOP, FROM, INTO, WHERE, ORDER BY, GROUP BY.  That’s all you need to perform most Log Parser operations.

Curiously, Log Parser has never received the amount of attention that I think it deserves.  Beyond a flurry of attention when it was first released, it seems to be mentioned rarely in official Microsoft communications or blogs.  Despite that, it remains a viable and valuable tool for parsing not just web server log files, but all types of structured text-based data.

In this post, rather than explaining how to use Log Parser. I’ll give a number of examples of its use.  In addition, I’ll document some useful locations where Log Parser information can be found on the web.