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Re: High-Profile Advocacy Opportunity: Vbulletin Forum

From: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Peter Eisentraut <peter_e(at)gmx(dot)net>,Josh Berkus <josh(at)agliodbs(dot)com>,Donnacha Mac Gloinn <postgresql(dot)org(at)donnacha(dot)com>,pgsql-advocacy <pgsql-advocacy(at)postgresql(dot)org>
Subject: Re: High-Profile Advocacy Opportunity: Vbulletin Forum
Date: 2004-06-22 22:07:58
Message-ID: 20040622220758.GA9969@dcc.uchile.cl (view raw or flat)
Thread:
Lists: pgsql-advocacy
On Tue, Jun 22, 2004 at 10:14:11PM +0100, Simon Riggs wrote:
> On Tue, 2004-06-22 at 21:05, Alvaro Herrera wrote:
> > On Tue, Jun 22, 2004 at 08:51:07PM +0100, Simon Riggs wrote:
> > 
> > > > Why is it better than COPY?
> > 
> > > COPY is designed for bulk data loading from files etc. Extended INSERTs
> > > are used to minimise the number of round-trips to the database when
> > > issuing a few number of similar INSERTs, as when you do an
> > > Order/Order-Line (i.e. Master and many similar Details records).
> > 
> > Huh?  I think you should be able to issue a single multivalued insert to
> > a single table -- two queries in your Order/Order-Line example, not one.
> 
> Better explained, that would be:
> **If you're doing an Order/Order-Line insert you'll do 1 INSERT to Order
> and then multiple similar INSERTs to Order-Line: the multiple INSERTs
> into Order-Line are when you'd use the extended INSERT feature.**

Yeah, I thought you could mean that.

Another nicety of multivalued insert compared to COPY is that you could
use currval() of a sequence that you just used in the insert to the
Order (of course, you can do that with a multiquery string too).


> > You can do the same in Postgres issuing several commands separated with
> > semicolons.  You can even use a single transaction by using BEGIN and
> > COMMIT at the start and end of the string.
> 
> Yes, there are PostgreSQL ways of doing things, not my point, I was
> explaining the MySQL rationale as I saw it.

Ah, ok.


> > I don't think REPLACE is a good idea (useless non standard MySQL-ism).
> > MERGE and multivalued INSERT are.  But they depend on someone actually
> > doing the work.  Both are on the TODO list, I think.
> 
> I think doing REPLACE is a trivial subset of MERGE, so should be easy
> enough to pull off once MERGE gets done.

Hmm ... and what if later the SQL committee adds a (different) REPLACE
command?  Anyway, Postgres doesn't follow MySQL's lead ... some people
here wants to rule the database world first and become the SQL editors
next. *chuckle*

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Pido que me den el Nobel por razones humanitarias" (Nicanor Parra)


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