Humor me: Postgresql vs. MySql (esp. licensing)

[Oliver Elphick]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

On Wed, 2003-10-08 at 20:28, Vivek Khera wrote:[color=blue][color=green][color=darkred]
> >>>>> "OE" == Oliver Elphick <olly@lfix.co.u k> writes:[/color][/color]
>
> OE> But as far as Debian is concerned, paragraph 1 applies:
>
> OE> 1. Free use for those who are 100% GPL
>
> [[ ... ]]
>
> OE> That makes it free under the Debian Free Software Guidelines, so I have
> OE> no grounds for requesting its removal. :-(
>
> So if I build and sell an appliance (hardware+softw are) based on
> debian and using the 'free' collection of software, suddenly I'm not
> in compliance with their license. Sounds like a time-bomb waiting to
> explode.[/color]

It's licensed under the GPL, which means that you can indeed sell it, SO
LONG AS you make your own source code available to your customer under
the GPL or a compatible licence. Nothing in the GPL stops you demanding
money for the software; what it requires is that you make your source
code available. It's whole purpose is to force the freeing of source
code; it is not much concerned with money. For example, I remember
years ago installing a DG Aviion operating system upgrade, where I found
that the compiler was gcc, with the GPL prominently attached. And every
embedded-Linux device is in the same situation.

MySQL's licence does not require you to buy a licence for _any_
commercial use, but only for commercial use where you do not release
your source code under a GPL-compatible licence.

There seems to be an awful lot of confusion about the GPL. Maybe
Microsoft's campaign has been bearing fruit in unlikely quarters...

--
Oliver Elphick Oliver.Elphick@ lfix.co.uk
Isle of Wight, UK http://www.lfix.co.uk/oliver
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
=============== =============== ==========
"Let no man say when he is tempted, I am tempted of
God; for God cannot be tempted with evil, neither
tempteth he any man; But every man is tempted, when he
is drawn away of his own lust, and enticed."
James 1:13,14


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[Bruce Momjian]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

Oliver Elphick wrote:[color=blue][color=green]
> > So if I build and sell an appliance (hardware+softw are) based on
> > debian and using the 'free' collection of software, suddenly I'm not
> > in compliance with their license. Sounds like a time-bomb waiting to
> > explode.[/color]
>
> It's licensed under the GPL, which means that you can indeed sell it, SO
> LONG AS you make your own source code available to your customer under
> the GPL or a compatible licence. Nothing in the GPL stops you demanding
> money for the software; what it requires is that you make your source
> code available. It's whole purpose is to force the freeing of source
> code; it is not much concerned with money. For example, I remember[/color]

You also have to allow anyone who is given the source code the ability
to freely distribute it too. Meaning, you can't prevent one of your
customers from putting the code up on ftp and distributing it to anyone.

--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.ph a.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073

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[nolan@celery.tssi.com]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

> One of my friend lost data with mysql yesterday.. The machine was taken down for[color=blue]
> disk upgrade and mysql apperantly did not commit the last insert.. OK he was
> using myisam but still..:-)[/color]

It sounds like that is more a problem with improper operating protocols
than with the underlying database.

Would PG know enough to do a commit regardless of how the database was
shut down? A second question is whether doing a commit is what the user
or application would always want to have happen, as it could result in a
half-completed transaction.
--
Mike Nolan

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[Alvaro Herrera]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

On Wed, Oct 08, 2003 at 07:03:19PM -0500, nolan@celery.ts si.com wrote:
[color=blue]
> Would PG know enough to do a commit regardless of how the database was
> shut down? A second question is whether doing a commit is what the user
> or application would always want to have happen, as it could result in a
> half-completed transaction.[/color]

If an open transaction is not explicitly committed and the client
disconnects, it is automatically rolled back.

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
Essentially, you're proposing Kevlar shoes as a solution for the problem
that you want to walk around carrying a loaded gun aimed at your foot.
(Tom Lane)

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[nolan@celery.tssi.com]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

> If an open transaction is not explicitly committed and the client[color=blue]
> disconnects, it is automatically rolled back.[/color]

So what would happen with MySQL? Does it leave the transaction
half-committed? The original implication was that data was lost, which
is what would happen with an uncommitted PG transaction as well.
--
Mike Nolan


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[Alvaro Herrera]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

On Wed, Oct 08, 2003 at 09:43:04PM -0500, nolan@celery.ts si.com wrote:[color=blue][color=green]
> > If an open transaction is not explicitly committed and the client
> > disconnects, it is automatically rolled back.[/color]
>
> So what would happen with MySQL? Does it leave the transaction
> half-committed? The original implication was that data was lost, which
> is what would happen with an uncommitted PG transaction as well.[/color]

It was not clear to me from the article that originally mentioned it
that it had an uncommitted transaction, though it may very well be the
case.

But given that ROLLBACK takes some unreasonable amount of time in MySQL,
what do you really expect? Did the rollback work when the poweroff was
requested? Or did it work only halfway, rendering the whole
"transactio n" model useless?

A "halfway rollback" would be one of the most stupid things I've heard
about.

--
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"El número de instalaciones de UNIX se ha elevado a 10,
y se espera que este número aumente" (UPM, 1972)

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[Karel Zak]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

On Wed, Oct 08, 2003 at 11:45:36AM -0400, Richard Welty wrote:[color=blue]
> On Wed, 8 Oct 2003 11:28:00 -0400 (EDT) John Wells <jb@sourceillus trated.com> wrote:
>[color=green]
> > It's my opinion that we should be using PG, because of the full ACID
> > support, and the license involved. A consultant my company hired before
> > bringing me in is pushing hard for MySql, citing speed and community
> > support, as well as ACID support.[/color]
>
> you should also cite conformity to standards. MySQL is significantly
> different from SQL standards in a number of regards. not that any are fully[/color]

I think very nice example is:

SELECT 'a' || 'b';

BTW, MySQL versions without transactions are unusable for 365/7/24
systems, because you cannot make backup of DB without transaction or
redo log.

Karel

--
Karel Zak <zakkr@zf.jcu.c z>

http://home.zf.jcu.cz/~zakkr/

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[Shridhar Daithankar]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

nolan@celery.ts si.com wrote:
[color=blue][color=green]
>>One of my friend lost data with mysql yesterday.. The machine was taken down for
>>disk upgrade and mysql apperantly did not commit the last insert.. OK he was
>>using myisam but still..:-)[/color]
>
>
> It sounds like that is more a problem with improper operating protocols
> than with the underlying database.[/color]

No. Problem is machine was shutdown with shutdown -h. It sends sigterm to
everybody. A good process would flsuh the buffers to disk before finishing.
Mysql didn't on that occasion.

Transactions or not, this behaviour is unacceptable for any serious app.
[color=blue]
>
> Would PG know enough to do a commit regardless of how the database was
> shut down? A second question is whether doing a commit is what the user
> or application would always want to have happen, as it could result in a
> half-completed transaction.[/color]

Do a shutdown -h on a live database machine with pg. It will gracefully shut
itself down.

Shridhar


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[Harald Fuchs]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

In article <20031009030518 .GD8265@dcc.uch ile.cl>,
Alvaro Herrera <alvherre@dcc.u chile.cl> writes:
[color=blue]
> It was not clear to me from the article that originally mentioned it
> that it had an uncommitted transaction, though it may very well be the
> case.[/color]

Sridhar mentioned MyISAM tables - thus no transactions at all.
[color=blue]
> But given that ROLLBACK takes some unreasonable amount of time in MySQL,
> what do you really expect? Did the rollback work when the poweroff was
> requested? Or did it work only halfway, rendering the whole
> "transactio n" model useless?[/color]

Been there, done that. You can kill the MySQL server when it's
rolling back a huge transaction. When you restart it, it just
continues the rollback.


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[Harald Fuchs]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

In article <20031009061602 .GB8513@zf.jcu. cz>,
Karel Zak <zakkr@zf.jcu.c z> writes:
[color=blue]
> BTW, MySQL versions without transactions are unusable for 365/7/24
> systems, because you cannot make backup of DB without transaction or
> redo log.[/color]

Huh? People have backed up their MyISAM tables with "mysqlhotco py" or
something like that for ages. This tool locks all tables and can take
a significant amount of time for large databases. Since many people
don't want that, they just create a small replication slave used
exclusively for backup.


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[Karel Zak]

Re: Humor me: Postgresql vs. MySql (esp. licensing)


On Thu, Oct 09, 2003 at 01:33:39PM +0200, Harald Fuchs wrote:[color=blue]
> In article <20031009061602 .GB8513@zf.jcu. cz>,
> Karel Zak <zakkr@zf.jcu.c z> writes:
>[color=green]
> > BTW, MySQL versions without transactions are unusable for 365/7/24
> > systems, because you cannot make backup of DB without transaction or
> > redo log.[/color]
>
> Huh? People have backed up their MyISAM tables with "mysqlhotco py" or
> something like that for ages. This tool locks all tables and can take[/color]
^^^^^
:-)[color=blue]
> a significant amount of time for large databases. Since many people
> don't want that, they just create a small replication slave used
> exclusively for backup.[/color]

How sure you with integrity of backup without transaction? For example
references between tables...

Karel

--
Karel Zak <zakkr@zf.jcu.c z>

http://home.zf.jcu.cz/~zakkr/

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[Bill Gribble]

MySQL is not free software. Re: Humor me: Postgresqlvs. MySql (esp. licensing)

On Wed, 2003-10-08 at 16:23, Joshua D. Drake wrote:[color=blue]
> Here is the simple thing about MySQL licensing. It is GPL. If you
> modify the mySQL source or you link a proprietary app to mySQL without
> a commercial license. You must distrubute your changes and or
> application as GPL or GPL compatibile.[/color]

You have two contradictory statements here, which unfortunately
represent the internal contradictions in MySQL's license (at least,
those versions after version 3.23.19, when MySQL AB adopted the current
licensing scheme).

Certainly, if MySQL is licensed under the GPL, you must distribute or
make available source code to any changed version of MySQL that you
distribute, or any other derivative works of MySQL that you distribute.
However, MySQL's stated license makes far greater requirements on those
who use MySQL.

Even though many distributors of MySQL, including the normally very
license-conscious Debian GNU/Linux, include only the GPL as its license,
there are in fact additional constraints which limit the rights that are
given by the GPL. MySQL AB's license information web page [1] includes
in plain language what their intent is, and that intent is not the GPL,
nor is it compatible with the GPL.

The non-commercial (free-of-charge) MySQL license extends the
requirement to make available source code to "your application",
regardless of whether or not your application is a derived work of
MySQL. All practical interpretations of the GPL, including the FSF's,
exclude from the requirement to distribute source code any works that
are collected by "simple aggregation", meaning they are present on the
same distribution medium or in the same distribution package as the
licensed work, but are not related to the licensed work by the sharing
of licensed components. MySQL does not distinguish between derivative
works of MySQL and those that are collected along with it by simple
aggregation.

So, for example, if I wish to sell a version of Debian with a
proprietary, closed-source installation tool (which does not use or
relate to MySQL in any way) and I wish to also include MySQL and its
source code in my distribution, I am required to get a commercial
license from MySQL. That is not consistent with the terms of the GPL
under which I received MySQL from Debian.

I don't know how to put it more plainly than that. Even though MySQL AB
claims that their product is licensed under the GPL, it is not, because
they put significant additional license terms on it that remove some
rights given by the GPL. The overall license terms of MySQL do not
meet any standard of "Free software" licenses that I know, including the
Debian Free Software Guidelines [2]. I believe that Debian and other
GNU/Linux distributions should move MySQL to their non-free sections,
along with other software that is "free for non-commercial use".

The consequences for any commercial enterprise using MySQL in any way
must be very closely examined, and certainly aren't obvious in the way
that the consequences of the GPL are obvious.

Thanks,
Bill Gribble

[1] http://www.mysql.com/products/licensing.html
[2] http://www.debian.org/social_contract#guidelines












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[bob parker]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

On Thu, 9 Oct 2003 01:28, John Wells wrote:[color=blue]
> Yes, I know you've seen the above subject before, so please be gentle with
> the flamethrowers.
>
> I'm preparing to enter a discussion with management at my company
> regarding going forward as either a MySql shop or a Postgresql shop.
>
> It's my opinion that we should be using PG, because of the full ACID
> support, and the license involved. A consultant my company hired before
> bringing me in is pushing hard for MySql, citing speed and community
> support, as well as ACID support.
>[/color]

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[Vivek Khera]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

>>>>> "OE" == Oliver Elphick <olly@lfix.co.u k> writes:

OE> MySQL's licence does not require you to buy a licence for _any_
OE> commercial use, but only for commercial use where you do not release
OE> your source code under a GPL-compatible licence.

So if I write my application in python, say, and only relase the .pyc
files, I'm not linked to mysql, but I use it via the API provided by
the python runtime. The GPL does not require me to release the source
code to my application, yet I'm using mysql in a commercial setting.
I believe that mysql will demand a license fee from me in this
situation.

It is very murky with mysql.

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[nolan@celery.tssi.com]

Re: Humor me: Postgresql vs. MySql (esp. licensing)

> > It sounds like that is more a problem with improper operating protocols[color=blue][color=green]
> > than with the underlying database.[/color]
>
> No. Problem is machine was shutdown with shutdown -h. It sends sigterm to
> everybody. A good process would flsuh the buffers to disk before finishing.
> Mysql didn't on that occasion.[/color]
[color=blue]
> Transactions or not, this behaviour is unacceptable for any serious app.[/color]

True, but was it because the shutdown scripts weren't set up properly
or does MySQL just not handle the 'kill' properly? (I would consider the
latter a serious bug.)

I still fault the operations protocol, part of what should be done in
setting up a production shop is testing various shutdown options, and it
sounds like that wasn't done in advance or they would have known to build
in extra steps for shutting down MySQL.
[color=blue]
> Do a shutdown -h on a live database machine with pg. It will gracefully shut
> itself down.[/color]

Is that true for all OS flavors and is it dependent upon the DBA having
set up proper shutdown scripts?

I'm not trying to be argumentative here or defending MySQL, just noting
that a shutdown process that isn't tested can cause problems even with
commercial databases. And as someone who has to put up with MySQL on
occasion, I'm always looking for problem areas for the DBA.
--
Mike Nolan

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