Linked by Thom Holwerda on Sat 11th May 2013 21:41 UTC
Windows "Windows is indeed slower than other operating systems in many scenarios, and the gap is worsening." That's one way to start an insider explanation of why Windows' performance isn't up to snuff. Written by someone who actually contributes code to the Windows NT kernel, the comment on Hacker News, later deleted but reposted with permission on Marc Bevand's blog, paints a very dreary picture of the state of Windows development. The root issue? Think of how Linux is developed, and you'll know the answer.
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RE[13]: Too funny
by Alfman on Tue 14th May 2013 15:45 UTC in reply to "RE[12]: Too funny"
Alfman
Member since:
2011-01-28

satsujunka,


"if you were to build your own custom SQL database over top file system primitives, it's unlikely to be as flexible or accessible as an SQL database"
...
"The bold part is what you're missing. And is why you're contradicting yourself. You are literally saying that an SQL database is less flexible and accessible then an SQL database. The backend is totally unimportant for non-performance considerations."

Oh I see, you modified my quote in order to create a contradiction. (please don't do that again!) This is a bit out of context for log files which we were discussing, but since your quite adamant that textfiles are just as good for implementing SQL databases, I'll address why I think you are wrong.

You *could* build an SQL database on top of any format you chose. I won't discourage you from trying it, but unless you create ODBC / JDBC / native data connectors for it, then you'd end up with a rather inaccessible SQL implementation. Still you *could* build all the SQL connectors and have a fully usable SQL database.


Now, conceptually your happy, but the implementation details are where problems begin cropping up. Almost any changes to records (changing data values or columns) mean re-sequencing the whole text file, which is not only inefficient by itself (particularly for large databases), but it means rebuilding all the indexes as well. Also many years of research have gone into the so-called ACID features you'll find in SQL databases. Consider atomic transactions, foreign key integrity, etc. SQL implementations are designed to keep the data consistent even in the event of a power loss, think about what that means for flat file storage.

Another issue is that flat text file makes efficient concurrency difficult, any change that one program is making would have to block other readers/writers to avoid data corruption, I think you'll agree that the entire text file needs one large mutex in order to guaranty that the textual data is in a consistent state. Although linux has advisory file locking, I don't think standard tools like grep use it. After all your work to make your "custom SQL database" use a text format, you still cannot safely use standard tools like grep on it without first making sure the database is taken offline.

So I ask you now, what is the advantage of having a text SQL engine over being able to export text from a binary SQL database?


The only criticism I can give merit to as a real fundamental problem is if you don't trust the database implementation to produce reliable results (for fun: I challenge you to find an instance of a popular database having produced unreliable query results on working hardware). For everything else you could export a text copy and even then I have to reiterate that it's my honest belief that for anyone who is proficient with SQL, hardly any would want to use the text tools by choice. SQL really is superior even for simple adhoc queries.


"And what 'advanced' features would apply to a log? There's only 1 record type. CSV provides sufficient capabilities to handle that."

For example, on one production system I import apache logs into a database, index them, and compute per-user aggregate statistics. The database correlates these hits with user accounts groups them by date for displaying monthly statistics for our users. These web statistics also get joined to the sales email statistics.

I won't pretend most log files need this amount of analytical power, they don't. But it's still nice to have this ability without first having to write programs to parse the text files and manually compute aggregates. I can (and have) written perl & php scripts to run similar computations by hand, but the database is the clear winner IMHO. Even if I'm just browsing the data and not manipulating it, I'd rather have a tabular spreadsheet interface over a flat file one.

I do appreciate how cleverly the text tools can be used in a unix shell, but the more I think about it the more I like the database approach. Maybe we need to stop thinking about it as "binary" versus "text", and think about it as different degrees of data abstraction.

Reply Parent Score: 3