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Re: [HACKERS] What can we learn from MySQL?

From: Alexey Borzov <borz_off(at)cs(dot)msu(dot)su>
To: Tim Conrad <tim(at)timconrad(dot)org>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>,PostgreSQL advocacy <pgsql-advocacy(at)postgresql(dot)org>
Subject: Re: [HACKERS] What can we learn from MySQL?
Date: 2004-04-27 17:52:01
Message-ID: 408E9DC1.9030105@cs.msu.su (view raw or flat)
Thread:
Lists: pgsql-advocacypgsql-hackerspgsql-www
Hi!

Tim Conrad wrote:
>>My favourite part of it is:
>>--------
>>MySQL uses traditional row-level locking. PostgreSQL uses something 
>>called Multi Version Concurrency Control (MVCC) by default. MVCC is a 
>>little different from row-level locking in that transactions on the 
>>database are performed on a snapshot of the data and then serialized. 
>>New versions of PostgreSQL support standard row-level locking as an 
>>option, but MVCC is the preferred method.
>>--------
> 
> Nice that you point out that incorrectly stated something. Even
> nicer that you don't tell me what the correct answer would be.
> Unfortunanatly, that's the best I could come up with with doing
> research with the documentation I could find on the subject. MVCC
> does a  lot more than can be easily contained in a sentance. 

The problem is that in MySQL
1) MyISAM does table-level locking;
2) BDB does row-level locking;
3) InnoDB does MVCC (mostly) like PostgreSQL.

PostgreSQL does support row-level locking (SELECT ... FOR UPDATE), table-level 
locking (LOCK TABLE ...), though this does not *replace* MVCC, as one may 
understand from the quotation.

>>MySQL's roadmap is complete bullshit. Subselects were first promised in 
>>4.0, which was "not that far away" [1] back in 1998! Well, they are in 
>>4.1, which is still alpha in 2004.
> 
> I realize this.  I also realize that having a nicely defined roadmap would
> give Postgres a hands up in this category. 

A hands up in *what* category? In bragging?

Should PostgreSQL developers write something along the lines of "PostgreSQL 9i 
(available Really Soon Now) will also be able to make coffee"?

Well, as you know about coffee now, why don't you add "make coffee" to your 
comparison table, with empty space in MySQL's and commercial DBMSs' columns and 
"in 9i" in PostgreSQL's one?



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