Also, Date mentions the notion that tables don't have to be mapped to individual files. For example, if the types of queries are known in advance, it could be possible to rearrange the data to be optimal for those queries. Currently, tables are just big serialized arrays. On Fri, June 9, 2006 9:55 am, Aaron Bingham wrote: > dananrg@xxxxxxxxx wrote: > >> I'm reading, and enjoying immensely, Fabial Pascal's book "Practical >> Issues in Database Management." >> >> >> > I also found this book very useful when I first started doing serious > database work. For a more thorough treatment of many of these issues, see > An Introduction to Database Systems by Chris Date. The latter book > is so full of detail that it is sometimes hard to follow, but it's worth > the effort. > >> Though I've just gotten started with the book, he seems to be saying >> that modern RDBMSs aren't as faithful to relational theory as they ought >> to be, and that this has many *practical* consequences, e.g. lack of >> functionality. >> >> Given that PostgreSQL is open source, it seems a more likely candidate >> for addressing Pascal's concerns. At least the potential is there. >> >> > Although some DBMSs have invented new ways to break the relational > model, the fundamental problems are in SQL. No DBMS based on SQL is going > to be able to support RM correctly. > >> Some questions: >> >> >> 1) Is PostgreSQL more faithful to relational theory? If so, do you find >> yourself using the additional functionality afforded by this? e.g. >> does it really matter to what you do in your daily work. >> > Within the limitations imposed by the SQL standard, PostgreSQL seems to > do about as well as could be expected, but falls short as all SQL DBMSs > must. For example, PostgreSQL allows NULLs and duplicate rows (there are > preventive measures against both of these but you have to be careful to > avoid them, and sometimes you can't). One feature of RM PostgreSQL lacks > are nested relations (a bad idea for base table design but useful in query > results). > > Regards, > > > -- > -------------------------------------------------------------------- > Aaron Bingham > Senior Software Engineer > Cenix BioScience GmbH > -------------------------------------------------------------------- > > > > ---------------------------(end of broadcast)--------------------------- > TIP 3: Have you checked our extensive FAQ? > > > http://www.postgresql.org/docs/faq > >
