-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 07/30/2010 08:00 AM, Tim Romano wrote: > Several things might be responsible for there being no "outpouring of > support" for a raw reverse function.
Also note that you are proposing it as a very specific workaround for a specific scenario which is why you want the codepoints reversed rather than being done "correctly" when dealing with combining unicode codepoints. ie your required reverse semantics are not correct for 100% of people who would want a reverse function :) - From your further description it is apparent that you don't actually want a reverse function, but rather a string endswith function that is not O(n). Another example usage is processing web logs, where for example you want to find all accesses to names ending in 'google.com'. > That the SQL dev team has not responded I take as an indication that this > would be very low priority for them, I don't think the issue was articulated well enough (I think my second paragraph above is better :-) and the solution you required is not a SQL standard nor fits in with how SQLite development works in general, and you rejected the existing means by which SQLite allows people to customise it. You can of course demand their attention through the mechanisms listed at: http://www.hwaci.com/sw/sqlite/prosupport.html > Anyway, the lack of such a function is only a problem for me vis-a-vis an > amalgamation distribution of SQLite. It is only a problem if you are using an environment where SQLite is hidden inside a black box and that environment prevents you from using any of the SQLite extension mechanisms. Given SQLite's very liberal license that really is a self inflicted problem. What I suggest you do is a survey of how other databases do this, and provide some timings when using SQLite as it currently stands and with a workaround such as using a custom reverse function. It becomes a far more compelling case when you can show query times going from unusable to quick, as well as some example usage scenarios. (Yes this is a fair bit of work, but that is exactly what you are requesting of the SQLite team - why should they do lots of work if you are not prepared to.) There are also many other possible solutions than a visible reverse function. For example an index behind the scenes could be created that allows searching from either end, or something similar with a collation. > I may decide to forget about it as a > target platform and rewrite the app as a web-service, where I would indeed > have access to the UDF mechanism. But there was merit in having the > application work in offline mode too. Are the data sets the same size? I'd expect offline use to be done with smaller data sets and using a server for when they are larger. Pulling numbers out of thin air, maybe using O(n) queries up to a million rows is just fine and after that you use the server with performance enhancements? Roger -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkxTDDMACgkQmOOfHg372QS4zACgg+X3EhdX0Ue4tz4IC9bUH+Ov CioAoN1+zhreXEGCtw0MCh5k7QcH/0Yn =zmY5 -----END PGP SIGNATURE----- _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
