ccc31807 <carte...@gmail.com> writes: > On Mar 3, 4:55 pm, toby <t...@telegraphics.com.au> wrote: >> > where you have to store data and >> >> "relational data" > > Data is neither relational nor unrelational. Data is data. > Relationships are an artifact, something we impose on the data. > Relations are for human convenience, not something inherent in the > data itself. > >> > perform a large number of queries. >> >> Why does the number matter? > > Have you ever had to make a large number of queries to an XML > database? In some ways, an XML database is the counterpart to a > relational database in that the data descriptions constitute the > relations. However, since the search is to the XML elements, and you > can't construct indicies for XML databases in the same way you can > with relational databases, a large search can take much longer that > you might expect. >
Most XML databases are just a re-vamp of hierarchical databases, which are one of the two common formats that came before relational databases. Hierarchical, network and relational databases all have their uses. Some 'xml' databases, like existsdb have some pretty powerful indexing technologies. while they are different to relational db indexing because they are based around hierarchies rather than relations, they do provide the ability to do fast queries in the same way that indexes in relational databases allow fast queries over relations. Both solutions can do fast queries, they are just optimised for different types of queries. Likewise, other database technologies that tend to fall into this category, such as couch and mungo are aimed at applications and problems that aren't suitable for the relational db model and are better suited to the types of applications they have been designed for. As usual, Xah's rantings are of little substance here. Yes, he is right that 'nosql' is essentially just another buzzword like 'web 2.0', but so what? This is an industry that loves its buzzwords.Often its just marketing hype or some convenience holder for a vague 'concept' some journalist, consultant or blogger wants to wank on about. You cannot hate or love 'nosql' without defining exactly what you mean by the term. Xah starts by acknowledging the term is ill defined and then goes on to say how he doesn't like it because it lacks the mathematical precision of the relational algebra that underpins the relational model. It seems somewhat ironic to put forward an argument focusing on the importance of precision when you fail to be precise regarding the thing your arguing against. His point is further weakened by the failure to realise that SQL and the relational model and relational algebra are different things. Not having SQL doesn't automatically mean you cannot have a relational model or operations that are based on relational algebra. SQL is just the convenient query language and while it has succeeded where other languages have not, its just one way of interacting with a relational database. As a language SQL isn't even 'pure' in that it has operations that don't fit with the relational algebra that he claims is so important and includes facillities that are really business convenience operations that actually corrupt the mathematical model and purity that is the basis of his poorly formed argument. He also overlooks the fact that none of the successful relational databases have remained true to either the relational model or the underlying theory. All of the major RDMS have corrupted things for marketing, performance or maintenance reasons. Only a very few vendors have stayed true to the relational model and none of them have achieved much in the way of market share, I wonder why? All Xah is doing is being the nets equivalent of radios 'shock jock'. He searches for some topical issue, identifies a stance that he feels will elicit the greatest number of emotional responses and lobs it into the crowd. He rarely hangs around to debate his claims. When he does, he tends to just yell and shout and more often than not, uses personal attack to defend his statements rather than arguing the topic. His analysis is usually shallow and based on popularism If someone disagrees, they are a moron or a fool and if they agree, they are a genius just like him. Just like true radio shock jocks, some willl love him and some will hate him. The only things we can be certain about are that reaction is a much hier motivator for his posts than conviction, there is probably an inverse relationship between IQ and support for his arguments and that his opinion probably has the same longevity as the term nosql. Now if we can just get back to debating important topics like why medical reform is the start of communism, how single mothers are leeching of tax payers, the positive aspects of slavery, why blacks are all criminals, how governments are evil, the holocaust conspiricy, why all muslims are terrorists, the benefits of global warming, the bad science corrupting our children's innocence and stop wasting time debating this technology stuff and please people, listen to your harts and follow your gut - don't let your intellect or so called facts get in the way, trust your emotions. Tim -- tcross (at) rapttech dot com dot au -- http://mail.python.org/mailman/listinfo/python-list
