Log to file or to database table?

Question

I'm developing a web application which uses MS SQL for various data: including users, user accounts, user licenses, license prices, invoices.
I need to log users' real-time usage of the system, and use that for monthly billing: e.g. log whenever a user gets a specific page/URL and bill users at the end of the month based on the number of pages they fetched.
Should I write these log events into a table in my MS SQL database ?
Should I write these log events into a non-SQL append-only log file?
Should I write these log events into a different log file for each user?
This is not an especially high-volume web site: for example, a maximum of 10,000 users each doing an average of 5 loggable events/day => 50,000 events / day = 30 events / minute = 18,000,000 events / year.
I'm asking because either option seems viable and I don't see whether one has a clear advantage.
The data associated with a billable event is simple, e.g.:
User ID (foreign key relationship to the Users table in SQL)
Date and time
URL of the billable page

Answer 1

Good day Tekken
Tekken
>> I need to log users' real-time usage of the system, and use that for monthly billing: e.g. log whenever a user gets a specific page/URL
The IIS already have a great built-in option of logging every request and response. Therefore it give you all the information that you need. It is highly recommended to use it for most cases, if you have this option and you control the IIS logs. The
default location of the log files is: %SystemDrive%\inetpub\logs\LogFiles
If your system content is based on database
for each page (That is something like: Information Management System, or Content Management System), and you need to point to the database server at
each page anyway, then and probably on then, you can use the same connection that you open to the database, in order to keep the information in the database.
Application like DotNetNuke (which is CMS) logs the information in the database by default, for example.
* If you have to be 100% that you do not lose anything then do not recommend to use your own external system like writing to a file from your application. In this case you better to use the database (but for most cases we do not care if we lose one visit
to a page if the server crush at that point, for example)
* I don't think that there is any need for different log file for each user. most common is to configure the iis to build new log file each day for each application. If you have a specific sub-application in the website then you can configure it with separate
logs.
* There several great free log analyzers for the iis logs. In several cases I prefer to actually move the information from the log file, using bulk insert, into the SQL Server but yet for most cases i prefer first writing it externally from the SQL Server.
Writing to file will not give us to keep  ACID and we might lose information in some cases. There is option to use NoSQL for fast logging, as well.
* if you do log into the database, then in most case you should not create indexes, and keep the table simple since it is more important to improve insert than select (you should never use update or delete on logs).
>> This is not an especially high-volume web site: for example, a maximum of 10,000 users each doing an average of 5 loggable events/day =>
50,000 events / day = 30 events / minute = 18,000,000 events / year.
This look like a very small activity and basically I guess (we don't have all the information to suggest) that Database solution should be OK in your case. Make sure that you do not use express edition and you use several CPU in the database, will make much
more reliable for multi threads and more activities on the website.
  Ronen Ariely
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