On Wed, Oct 12, 2005 at 05:12:05AM -0500, pilot pirx wrote: > Subject: [sqlite] Please, please do _not_ remove this feature from SQLite...
> While using SQLite for some time (with R package, www.r-project.org) > I did admire its functionality and speed. Then I did discover a > hidden SQLite feature of immense usefulness - not available in other > databases. SQLite can compute Fibonacci numbers! (I will explain why Transaction visibility features do vary, although often it doesn't matter anyway. E.g., here's a dicussion of how (at least as of early 2004), PostgreSQL's docs were quite confused about certain subtleties, but what I find interesting, is this was still something that in practice had never really mattered to the mostly hard-core RDBMS programmers talking about it in that thread: http://openacs.org/forums/message-view?message_id=176198 > UPDATE fib SET > val = (SELECT h1.val FROM fib as h1 where pos = fib.pos - 1) + > (SELECT h2.val FROM fib as h2 where pos = fib.pos - 2) > WHERE pos > 2; I don't see why this is such a great feature. Without it, worst case, you could still write a simple little loop which would issue one update statement for each row, all within a single transaction. No? > This is an _immensely_ useful functionality when one needs to > compute various recursive functions. For example exponential moving > average, used frequently in financials. Or Kalman filter (and many Vastly more useful for moving average and the like would be real windowing/grouping functions, like Oracle's "analytic" functions. I'm not thrilled by their particular syntax, but the functionality is INCREDIBLY useful. (And on the other hand, I haven't thought of any obviously better syntax, either.) Hm, an amendement to the SQL:1999 spec added windowing support, and SQL:2003 includes that, I think as features T611, "Elementrary OLAP functions" and T612, "Advanced OLAP functions". Apparently Fred Zemke of Oracle was the author of that SQL spec, and IBM also supported it, so the SQL:2003 syntax and behavior is probably very similar (maybe identical?) to what Oracle 8i, 9i, and 10g and IBM's DB2 already have. PostgreSQL, as of 8.0, doesn't support it yet. http://www.wintercorp.com/rwintercolumns/SQL_99snewolapfunctions.html http://www.ncb.ernet.in/education/modules/dbms/SQL99/OLAP-99-154r2.pdf http://www.wiscorp.com/sql/SQL2003Features.pdf http://troels.arvin.dk/db/rdbms/#select-limit-offset http://www.postgresql.org/docs/8.0/interactive/features.html http://en.wikipedia.org/wiki/SQL http://www.sigmod.org/sigmod/record/issues/0403/E.JimAndrew-standard.pdf http://www.oracle.com/oramag/oracle/01-jul/o41industry.html SQLite basically supports just SQL-92, it doesn't have any of these newer SQL:1999 or SQL:2003 features, right? Using SQLite in conjunction with a powerful statistical data analysis programming language like R is an excellent example of a use where windowing functions can be hugely helpful. Unfortunately, I've never had a compelling need to use SQLite for that, otherwise I'd probably take a shot at adding support for the SQL:2003 Window/OLAP stuff. :) -- Andrew Piskorski <[EMAIL PROTECTED]> http://www.piskorski.com/
