Em 06/09/2012 00:39, Scott Marlowe escreveu:
On Wed, Sep 5, 2012 at 8:56 PM, Edson Richter <edsonrichter@xxxxxxxxxxx> wrote:
Em 05/09/2012 23:49, Chris Travers escreveu:
Regarding MySQL vs PostgreSQL:
MySQL is what you get when app developers build a database server.
PostgreSQL is what you get when db developers build a development
platform.
There really isn't anything more to say about it.
This kind of claim is just to feed flame wars. Don't think I need to state
that a "db developer" becomes a "app developer" as soon as he start to
develop any database server code, right?
I kind of agree with both of you somewhat.
A lot of developers think of their data in a hierarchical manner. If
so a simple key->value data store is often your best answer.
MySQL's basic design is that of a simple key->value data store
parading as a relational database. While it's had a lot done to it to
make it better in the role of relational data manager, it's still got
a lot of baggage from back in the day that means that as you go from
simple data store to complex relational data management, you start to
notice warts, like a planner that's dumb as a stump, and very simple
join methods that make complex queries painfully slow. For people who
are just storing and retrieving lots of simple data, it's still great.
PostgreSQL's heritage was correctness in SQL and set theory. The
obvious example is queries that MySQL, or at least older versions of
it, would run that Postgresql would, correctly, throw an error on.
Simple example is:
select a,b,c from sometable group by a;
assuming there's no PK on a, this query SHOULD throw an error because
in that case which values you get for b and c are both undefined, and
the SQL standard says that it should therefore throw an error.
Performance and easy use were not a priority for most of its early
life, so the MySQL philosophy of "just run the query and give me the
wrong answer like I asked" wasn't good enough.
They started from very different places, and while they've moved
towards each other over the last decade, their heritages mean they
still have very different strengths and weaknesses.
If you write code by grabbing small globs of data from the db, doing
the mangling in the CPU, then stuffing them back out to the db, MySQL
might be your best choice. If you write code by transforming data sets
in the database, then PostgreSQL is likely your best bet.
The problem you run into is that if you're only familiar with one db
and you're trying to use it like the other one. MySQL will dominate
at apps that mostly read a lot of tiny bits of data and occasionally
write chunks of code out. PostgreSQL will dominate at lots of atomic
updates or large data transformations all taking place in the db
layer, not in app code.
Yes, I heard from a beginner devel that he likes MySQL because it gives
less errors. PostgreSQL was always bugging his app complaining about
some "foreign keys".
I just had to get out for laugh :-)
Nevertheless, I've a large app, and I admit: I tried to run with
MySQL+InnoDB. I'll never do the same mistake twice. My data got corrupt
(foreign keys have been ignored, as well primary keys), and I got lots
of zombie records in database.
Nowadays, I just limit my self to adults databases: PostgreSQL (my
preferred on last 5 years because it just works), MS SQL (because I
worked with it for most of my professional life since 1990s: and yes, I
used it when it was just Sybase's core), Oracle (besides I think it's
like a big expensive White Elephant) and Db2, that surprised me in its
last incarnation.
What I feel missing in PgSQL? Tools that help me to improve performance.
Every time I need to analyze a query, I miss the MS SQL Server
performance analyzer tool, and the Db2 optimizer :-)
But life is like that, and I get used to it. And PostgreSQL have been
working very weel since 8.4 for me (by today, all my databases
(development and production) run 9.1 without any trouble).
Regards,
Edson
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