[plug] SQL Servers

[John Summerfield]

> John Summerfield wrote:
> > 
> > > Hi Paul
> > >
> > > Go with Postgres. It has commit and rollback, which MySQL doesnt have.
> > > MySQL might be faster than Postgres but who cares! BTW MySQL is verrryy
> > > fast at simple queries, but its SQL is pretty restricted and the
> > > developers have 'cut a lot of corners' to boost performance. Also
> > > Postgres is GPL I think and MySQL is not (?).
> > >
> > > FWIW There is a lot of energy behind Postgres, maybe more so than with
> > > MySQL.
> > 
> > I have used PostgresSQL. Runs like a lame dog. Couldn't see any evidence
> > it has any understanding of a transaction: it cheerfully returns
> > uncommitted data to an enquiry. Its not relational either.
> >
> 
> How do you mean 'Its not relational'

Codd & Date outlined the criteria which a DBMS had to meet to be 
relational; PG doesn't meet them and the lack of these means extra work 
for the programmers.

While it might not cost any money to BUY, increased productivity 
attainable from using a relational DBMS makes it worth paying money for it.

Unless you're a student and using it as a tool to learn sql.


In the simple case of a payroll system (one of the early uses of a 
computer), one might have a table comprising basic information about 
employees; employee number, name, address etc.

On examining the data, you will see good sense to creating a table of 
locations: suburb|town and postcode. Saves storage, simplifies application 
design.

A relational DBMS will allow you to define a relationship between 
employees and location such that you cannot create an employee row for a 
non-existent location. Neither can you delete a location for which 
employee rows exist.

The checking's done in one location; the RDBMS. If you use PG, you need to 
check this rule in your code, at the points where you insert employee 
rows, at the points where you remove locations: potentially in many places 
in the code and many opportunities to add a few bugs.


If you're paying programmers, give them decent tools. Increased 
productivity will save the cost of the hardware software.



  
> > Did I mention that it's slow?
> > 
> 
> PostgresSQL runs like a lame dog when compared to MySQL (so do a lot of
> SQL engines).

PostgresSQL runs like a lame dog PERIOD. I have observed PostgresSQL doing 
absolutely stupid things such as using disk files (and big ones) to sort 
data that would comfortably fit in (virtual) memory and be sorted in one 
hundredth of the time.

-- 
Cheers
John Summerfield
http://os2.ami.com.au/os2/ for OS/2 support.
Configuration, networking, combined IBM ftpsites index.