Mattia, I NEVER said I was a "master of relational databases", or anything like that. The power of indexing is apparent, even to amateurs! Databases do not reduce complexities. They actually increase it somewhat, BUT they take advantage of organization, to reduce the time for queries. I said "this was a database problem", because the OP said he wanted to query a database, and for NO other reason.
I said I've setup and managed two databases, and coded my own programs that worked with both of them, regularly. Just read the manuals that came with the databases (they were expensive!), and I learned quite a bit. I've also worked in Real Estate, and used the listing service database, many times. When you say: "if you sum the time required to build indicies, and the time required to solve the problem you will NEVER, repeat NEVER, require less time that(n), using the old lovely algorithmic way, and this is true for ANY problem"., YOU ARE PERFECTLY CORRECT - BUT ONLY FOR THE ** FIRST ** indexing of the record. After the record has been properly indexed, the queries are MUCH FASTER than ANY algorithmic solution - because in a sense, the answer is already available - it's "precomputed", almost. It's like you, trying to algorithmically solve for 100,000 places, all the integers approximating Pi. You have a "lovely, fast" algorithm. But the database has the numbers ALREADY IN A database, and just has to look them up. It wins EASILY. That's what a database is all about. Yes, it takes some time to index the records, and fields, but once that's done, your queries are MUCH FASTER than anything else. This: ----------------------------------------- Given a number of cities and the costs of traveling from any city to any other city, what is the cheapest round-trip route that visits each city once and then returns to the starting city? ----------------------------------------- is not a query for a database. To get this info, you'd have to make a very sophisticated query, possibly using the databases own language, which would then generate and execute the multiple queries needed to get this answer for you. Databases don't usually answer such sophisticated questions. They answer simple queries like "What's the cheapest airline ticket to Tokyo leaving on Wednesday evenings, between 6 and 9 p.m.?" They aren't problem solvers, they just provide data, on demand, very efficiently, usually to a great many user's. Again, databases do NOT reduce complexity. They reduce the amount of time needed to find data, AFTER that data has been indexed, etc.. NOT BEFORE! I would never call you a "mad" anything, except in rhetorical jest. Sounds like a breakthrough here - "So that, if you say: "with a database and indices you can solve the problem in a faster way", ok, I can agree ... " Adak --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/algogeeks -~----------~----~----~----~------~----~------~--~---
