Orchid XP v7 wrote:
> Tom Galvin wrote:
> 
>>> I'm going to build [yet another] helpdesk application.
>>>
>>
>> Then mysql is more than adequate to the task.
> 
> I disagree.

Hmmm who should I listen to? Gail the professional DBA, who is flown all 
over the world for database technology conferences, with many years of 
experience, or Andrew?  Sorry mate.



> 
> I'll take a look. It's probably too complicated though. 
> 

Glad you are so openminded.

Here's another one that runs on Active Server Pages with an MS Access 
Database or MS SQL backend.

http://www.liberum.org/

It's been running at major companies for years with great reliability 
and users love it.  Some people even modified it to use mysql.

Post a reply to this message

Orchid XP v7 wrote:
> It just worries me that the designers of this system fundamentally think 
> that transaction integrity is so unimportant that it's not even the 
> default, that's all.

Know something? The default is also to commit after every statement on 
most DBs too. So? :-)

Yes, MySql *started out* tremendously simplified. But it's like you're 
complaining about how DOS looses disk clusters if you don't close the 
file properly, while evaluating XP.

> That's only one way of implementing transactional integrity. (And, IMO, 
> not a very good way.)

Actually, I think there are a number of ways to do it, depending on the 
table. You can even use explicit locks to enforce at least the I of ACID 
on the non-transactional tables.

>> Whatever you do to enforce transactional integrity? It takes resources.
> Now that at least is a valid statement.

Yah. In my experience, it's about a 5:1 ratio. When I realized that, I 
changed most of my tables to non-transactional. There's nothing I'm 
running on the tables that isn't idempotent.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Gilles Tran wrote:
> "Orchid XP v7" <voi### [at] devnull> a écrit dans le message de news: 
> 47642e2a$1@news.povray.org...
>> It just worries me that the designers of this system fundamentally think 
>> that transaction integrity is so unimportant that it's not even the 
>> default, that's all.
> 
> It's not the default because it's not needed in many database applications.

Right. Apparently you have a different idea of "application" to what I 
have...

> Frankly, it looks like you just discovered the word "database" yesterday, 
> fell in love with a couple of buzzwords even though you still have strictly 
> no idea about what a database it and how it works (this thread started about 
> *** CSV files *** being used for testing your database). Sorry mate, but you 
> can't spout utter nonsense about MySQL and Access being "toys" and be taken 
> seriously after that. Get some experience first.

Right. And the 3 modules in database design I took during my degree 
looking at different transaction isolation levevls and so forth was 
probably balony too - along with the 3 A* grades I got for those modules.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Tom Galvin wrote:
> Gilles Tran wrote:
> 
>> Frankly, it looks like you just discovered the word "database" 
>> yesterday, fell in love with a couple of buzzwords even though you 
>> still have strictly no idea about what a database it and how it works 
>> (this thread started about *** CSV files *** being used for testing 
>> your database).
>>
> 
> You forgot reinventing the wheel.
> 
> He's writing a helpdesk!  That's IT 101.
> 
> 
> If it's for fun, that's one thing.  If it's to meet a business need, 
> then put in one that has been tested, debugged and gained a little 
> maturity.  Your users will thank you, and the person who takes the job 
> after you will be deligheted not to inherit a undocumented 
> haskell/oracle monster.

I'm writing it because I'm fed up of everybody using Excel spreadsheets 
to record everything when we could use a real database, that's all. It's 
not like I'm planning on building a *large* system...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Darren New wrote:

> Know something? The default is also to commit after every statement on 
> most DBs too. So? :-)

Really? I've yet to see that...

(We won't go into what a hugely bad idea that would be.)

> Yes, MySql *started out* tremendously simplified. But it's like you're 
> complaining about how DOS looses disk clusters if you don't close the 
> file properly, while evaluating XP.

So you're seriously telling me that the amaturish little program that's 
not even transactional by default has somehow magically become an 
enterprise-level product?

>>> Whatever you do to enforce transactional integrity? It takes resources.
>> Now that at least is a valid statement.
> 
> Yah. In my experience, it's about a 5:1 ratio. When I realized that, I 
> changed most of my tables to non-transactional. There's nothing I'm 
> running on the tables that isn't idempotent.

5:1 time or space? On which specific database implementation? (It's not 
like it will be the same for all of them.)

Personally, if I had the option if making the system go 5x faster, but 
possibly screw up, I'd stick with the slow mode. But apparently that's 
just me...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Tom Galvin wrote:
> Darren New wrote:
>>
>> Damn you're dense. :-)
> 
> He does program in Haskell.

Sorry. I was hoping that would be taken in the spirit of the 
smiley-face.  :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Darren New wrote:
> Tom Galvin wrote:
>> Darren New wrote:
>>>
>>> Damn you're dense. :-)
>>
>> He does program in Haskell.
> 
> Sorry. I was hoping that would be taken in the spirit of the 
> smiley-face.  :-)

It does seem a little uncalled for.

Still, I've been called much worse...

(And at least he didn't threaten to rape my family.)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Orchid XP v7 escribió:
> Gilles Tran wrote:
>> "Orchid XP v7" <voi### [at] devnull> a écrit dans le message de news: 
>> 47642e2a$1@news.povray.org...
>>> It just worries me that the designers of this system fundamentally 
>>> think that transaction integrity is so unimportant that it's not even 
>>> the default, that's all.
>>
>> It's not the default because it's not needed in many database 
>> applications.
> 
> Right. Apparently you have a different idea of "application" to what I 
> have...

A program to organize your CD collection counts as an application.

Post a reply to this message

Orchid XP v7 wrote:
> Darren New wrote:
> 
>> Know something? The default is also to commit after every statement
>> on most DBs too. So? :-)
> 
> Really? I've yet to see that...

Funky. It looks like oracle doesn't do transactions by default either:
http://www.oracle.com/technology/documentation/berkeley-db/db/gsg_txn/C/enabletxn.html

Oh, and look. Microsoft sql server:
Autocommit mode is the default transaction management mode of Microsoft®
SQL Server™.
http://msdn2.microsoft.com/en-us/library/aa213069(SQL.80).aspx

> So you're seriously telling me that the amaturish little program
> that's not even transactional by default has somehow magically become
> an enterprise-level product?

Yes.  Well, no, not magically.  By dint of hard work by dozens or
hundreds of people over the course of five or ten years.

"Are you seriously telling me this ameturish DOS thing that doesn't even
support processes has somehow magically become a serious multiuser
enterprise-level operating system?

> 5:1 time or space? On which specific database implementation? (It's
> not like it will be the same for all of them.)

Time.

> Personally, if I had the option if making the system go 5x faster,
> but possibly screw up, I'd stick with the slow mode. But apparently
> that's just me...

Except, as explained, it's not a case of "probably screw up". I have one
processes that inserts independent records into the database, and
another that looks at the most recent record with some particular
attribute. I fail to see how the lack of transactions will damage that.

> Right. And the 3 modules in database design I took during my degree looking at
different transaction isolation levevls and so forth was probably balony too - along
with the 3 A* grades I got for those modules.

You must have a different definition for "experience" than usual.

 From another part of the thread...
> It does seem a little uncalled for.

Yah. Sorry. But seriously, dude, when several someones tell you you're 
wrong, and point you to the information, and it's written right there in 
front of you, arguing that "you don't believe it" makes you seem kind of 
dense. Especially when it's not God you're arguing about, but an 
open-source well-documented program used by thousands of companies all 
over the world.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Orchid XP v7 wrote:
> Darren New wrote:
>> Tom Galvin wrote:
>>> Darren New wrote:
>>>>
>>>> Damn you're dense. :-)
>>>
>>> He does program in Haskell.
>>
>> Sorry. I was hoping that would be taken in the spirit of the 
>> smiley-face.  :-)
> 
> It does seem a little uncalled for.
> 


Andrew has a penchant for doing things the hard way for perceived 
elegance.  Haskell is but one example.

He also is inclined to disregard the voice of experience, with some 
regularity.

If it seems harsh, good.  Maybe he will take the blinders of dogma off 
for a second and listen.

Post a reply to this message

Orchid XP v7 wrote:

> 
> I'm writing it because I'm fed up of everybody using Excel spreadsheets 
> to record everything when we could use a real database, that's all. It's 
> not like I'm planning on building a *large* system...
> 


Why reinvent the wheel?

Post a reply to this message

"Tom Galvin" <tom### [at] impnospamorg> wrote in message
news:476446ac@news.povray.org...
> Orchid XP v7 wrote:
> > Tom Galvin wrote:
> >
> >>> I'm going to build [yet another] helpdesk application.
> >>>
> >>
> >> Then mysql is more than adequate to the task.
> >
> > I disagree.
>
> Hmmm who should I listen to? Gail the professional DBA, who is flown all
> over the world for database technology conferences, with many years of
> experience, or Andrew?  Sorry mate.

Actually Darren wrote that, but thanks for the vote of confidence.

Given a choice, I'd listn to Darren who's worked extensivle (from what he
says) with MySQL. Personally I'm a SQL Server fan.

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:476457f1$1@news.povray.org...
> Darren New wrote:
>
> > Know something? The default is also to commit after every statement on
> > most DBs too. So? :-)
>
> Really? I've yet to see that...

How many database variations have you worked with? Oracle and ....

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:47645555$1@news.povray.org...
> Gilles Tran wrote:
>> Get some experience first.
>
> Right. And the 3 modules in database design I took during my degree...

University != experience.

You say that as if you're the only  person here who did database courses at
university. You're not.

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:47642e2a$1@news.povray.org...
>
> >> Why do you need to lock things to enforce transactional integrity?
> >> Locking is only one (suboptimal) way to solve the problem.
>
> That's only one way of implementing transactional integrity. (And, IMO,
> not a very good way.)

So, in your vast experience of databases, how would you do it?

Post a reply to this message

"andrel" <a_l### [at] hotmailcom> wrote in message
news:476### [at] hotmailcom...
> >
> There is a difference between stating that a program can not do
> something and asking the p.o-t for their opinion and experience. In
> practice the result here is the same, mainly because there are a lot of
> friendly people here that have com to know you over the years. IRL your
> mileage may vary. One of the main differences IRL is that the former
> tends shuts down all communication, while the latter invites the other
> to participate in an exchange of ideas.

And IRL, the former, if you are wrong, can do sufficinet damage to your
reputation that it takes months or longer to recover. Especially if you are
in a position where your word is trusted

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> a écrit dans le message de news: 
47645555$1@news.povray.org...

> Right. And the 3 modules in database design I took during my degree 
> looking at different transaction isolation levevls and so forth was 
> probably balony too - along with the 3 A* grades I got for those modules.

So why are you asking newbie questions about ODBC and keep having these 
far-out opinions about things you are visibly ignorant about? Why can't you 
find the information by yourself? How much difficult it is to actually look 
up the MySQL (or Word, or whatever software or thing baffles you) manual to 
verify your claims? How difficult it is to actually listen to what 
professionals like Darren and Tom and Gail are telling you? I told you 
before: be ignorant is all right, being and acting clueless much less so. If 
you want to be taken seriously (and expect more than snarky replies in the 
future), don't act like a 15-year old script kiddie.

G.

Post a reply to this message

Gail Shaw wrote:
> 
> Actually Darren wrote that, but thanks for the vote of confidence.
> 
> Given a choice, I'd listn to Darren who's worked extensivle (from what he
> says) with MySQL. Personally I'm a SQL Server fan.
> 
> 

You and Darren have both given him good advice.  The quoted portion is 
just myself and Andrew, though this thread has grown a few similar branches.

Post a reply to this message

Orchid XP v7 wrote:
> Really? I've yet to see that...

BTW, GIYF. Google for "autocommit" and the name of your database of 
choice. It's really *easy*, ya know. :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Gail Shaw wrote:
> Actually Darren wrote that, but thanks for the vote of confidence.

I'm not sure what I wrote, but I don't think it was anything there 
quoted. :-)

> Given a choice, I'd listn to Darren who's worked extensivle (from what he
> says) with MySQL. Personally I'm a SQL Server fan.

I've done a bunch of SQL Server, too. MySql for Linux, SQL Server for 
Windows. Depends on the technology talking to the server. I tend not to 
use a lot of the fancy stuff that isn't particularly portable (enforcing 
privs in the database, returning multiple tables from a query, etc), and 
I don't tend to do a whole lot of DBA infrastructure things myself (like 
setting up hot fall-over spares etc).

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Darren New wrote:

> It's really *easy*, ya know. :-)
> 

Not if you are googlephobic!

Post a reply to this message

"Darren New" <dne### [at] sanrrcom> wrote in message
news:476564ca$1@news.povray.org...
> Gail Shaw wrote:
> > Actually Darren wrote that, but thanks for the vote of confidence.
>
> I'm not sure what I wrote, but I don't think it was anything there
> quoted. :-)

Thread go so branched, I couldn't work out who said what and where. I knew I
didn't say it though.

> I've done a bunch of SQL Server, too. MySql for Linux, SQL Server for
> Windows. Depends on the technology talking to the server. I tend not to
> use a lot of the fancy stuff that isn't particularly portable (enforcing
> privs in the database, returning multiple tables from a query, etc),

My stuff (fortunatly) doesn't need to be portable, so I can go as fansy as I
like.

> and
> I don't tend to do a whole lot of DBA infrastructure things myself (like
> setting up hot fall-over spares etc).

Me neither. *shudder* I joke that if asked to backup a database, I'd have to
check the manual for the syntax. I'm more a developer that specialises in
performance tuning. Is fun, most days

Post a reply to this message

Tom Galvin wrote:

> Why reinvent the wheel?

I was hoping that if I make it simple enough, it will be impossible to 
misconfigure it. ;-)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Gail Shaw wrote:

> University != experience.

True. But my point is that I'm not entirely clueless about what 
databases are and how they work. I actually know stuff about this stuff.

> You say that as if you're the only  person here who did database courses at
> university. You're not.

I just object to being told I know nothing about databases when actually 
I do. I don't claim to be a world-renound expert, but I do know *something*.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Nicolas Alvarez wrote:

>> Right. Apparently you have a different idea of "application" to what I 
>> have...
> 
> A program to organize your CD collection counts as an application.

Indeed. A different kind of application to the idea I have in mind. :-)

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Gilles Tran wrote:

> So why are you asking newbie questions about ODBC

Because I'm not familiar with that particular technology, and I thought 
somebody else here might be. (And I was right...)

> and keep having these 
> far-out opinions about things you are visibly ignorant about?

I see. So thinking that transactions matter is "far-out" and "visibly 
ingorant"?

> Why can't you 
> find the information by yourself? How much difficult it is to actually look 
> up the MySQL (or Word, or whatever software or thing baffles you) manual to 
> verify your claims?

Um... I did? [At least, I read the MySQL manual, and spent some time 
using it.]

> How difficult it is to actually listen to what 
> professionals like Darren and Tom and Gail are telling you?

When somebody says "oh yeah, transactions aren't really all that 
important" when I spent 4 months learning about how important 
transactions are, I have to think "hmm, who is right here?"

> I told you 
> before: be ignorant is all right, being and acting clueless much less so. If 
> you want to be taken seriously (and expect more than snarky replies in the 
> future), don't act like a 15-year old script kiddie.

Some days I wonder why I talk at all...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Gail Shaw wrote:
> "Orchid XP v7" <voi### [at] devnull> wrote in message
> news:476457f1$1@news.povray.org...
>> Darren New wrote:
>>
>>> Know something? The default is also to commit after every statement on
>>> most DBs too. So? :-)
>> Really? I've yet to see that...
> 
> How many database variations have you worked with? Oracle and ....

5 points to Gail Shaw.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

Gail Shaw wrote:
> "Orchid XP v7" <voi### [at] devnull> wrote in message
> news:47642e2a$1@news.povray.org...
>>>> Why do you need to lock things to enforce transactional integrity?
>>>> Locking is only one (suboptimal) way to solve the problem.
>> That's only one way of implementing transactional integrity. (And, IMO,
>> not a very good way.)
> 
> So, in your vast experience of databases, how would you do it?

Personally I prefer Oracle's lockless multiversion system - although 
obviously that has its own set of drawbacks.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

On Mon, 17 Dec 2007 16:33:54 +0000, Orchid XP v7 wrote:

> Gail Shaw wrote:
> 
>> University != experience.
> 
> True. But my point is that I'm not entirely clueless about what
> databases are and how they work. I actually know stuff about this stuff.
> 
>> You say that as if you're the only  person here who did database
>> courses at university. You're not.
> 
> I just object to being told I know nothing about databases when actually
> I do. I don't claim to be a world-renound expert, but I do know
> *something*.

Hey, Orchid's got teeth!  :-)

(This is the sort of confidence you NEED to show more often)

Jim

Post a reply to this message

"Jim Henderson" <nos### [at] nospamcom> wrote in message 
news:4766b26e$1@news.povray.org...
> On Mon, 17 Dec 2007 16:33:54 +0000, Orchid XP v7 wrote:
>
>> Gail Shaw wrote:
>>
>>> University != experience.
>>
>> True. But my point is that I'm not entirely clueless about what
>> databases are and how they work. I actually know stuff about 
>> this stuff.
>>
>>> You say that as if you're the only  person here who did 
>>> database
>>> courses at university. You're not.
>>
>> I just object to being told I know nothing about databases when 
>> actually
>> I do. I don't claim to be a world-renound expert, but I do know
>> *something*.
>
> Hey, Orchid's got teeth!  :-)
>


So did Audrey (II); friend of Orin Scrivello, DDS.

Barking mad as well as a hot house greenie now, eh?

Uni courses qualify an applicant as much as being a
Microsoft Certified Professional. The former might
make for a trainable PFY for some kindly BOFH.

Rare is the production team that will allow obstructive
newbies to prevent due dates being met.

ObTwainism: "It is better to keep your mouth closed and let
people think you are a fool than to open it and remove all doubt."

Post a reply to this message

On Mon, 17 Dec 2007 10:34:37 -0800, pan wrote:

> "Jim Henderson" <nos### [at] nospamcom> wrote in message
> news:4766b26e$1@news.povray.org...
>> On Mon, 17 Dec 2007 16:33:54 +0000, Orchid XP v7 wrote:
>>
>>> Gail Shaw wrote:
>>>
>>>> University != experience.
>>>
>>> True. But my point is that I'm not entirely clueless about what
>>> databases are and how they work. I actually know stuff about this
>>> stuff.
>>>
>>>> You say that as if you're the only  person here who did database
>>>> courses at university. You're not.
>>>
>>> I just object to being told I know nothing about databases when
>>> actually
>>> I do. I don't claim to be a world-renound expert, but I do know
>>> *something*.
>>
>> Hey, Orchid's got teeth!  :-)
>>
>>
> 
> So did Audrey (II); friend of Orin Scrivello, DDS.

[...]

My point here is that he's actually stood up and said "now wait just a 
damned minute" - something that he has needed to do for a while.  I don't 
disagree with anything you said about the qualifications, theory and 
reality are two entirely different things.  But it's good that he's taken 
the chance to stand up and say something forceful rather than to just say 
"oh, OK, I guess I'm dumb" and slink off into the darkness.

It takes practice to stand up and do that.  It takes experience to know 
when it's the right thing to do, and that's something that comes with 
time.

So I still say "well done!"

Jim

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:4766a720@news.povray.org...
>
> Personally I prefer Oracle's lockless multiversion system - although
> obviously that has its own set of drawbacks.

Yup. Storage/memory

SQL's got that now too. I considered switching one of my main apps over to
use version store rather than locking, but I didn't have a compelling reason
to do so.

Locking is a minimal overhead when transactions are kept short.

> --
> http://blog.orphi.me.uk/
> http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:4766a681$1@news.povray.org...
> Gilles Tran wrote:

> > and keep having these
> > far-out opinions about things you are visibly ignorant about?
>
> I see. So thinking that transactions matter is "far-out" and "visibly
> ingorant"?

No, but saying that transactions are essential and anything that doesn't
implement them is a toy, on the other hand....

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:4766a4d1$1@news.povray.org...
> Gail Shaw wrote:
>
> > University != experience.
>
> True. But my point is that I'm not entirely clueless about what
> databases are and how they work. I actually know stuff about this stuff.
>

Yup. You know the theory. In practice however things are sometimes done
differently. Not because theory is wrong, but because sometimes shortcuts
are necessary.

In theory, you want to prevent any form of data anomaly from multiple
accesses. In reality, that often reduces concurrency to unacceptable levels,
so some possible anomolies are accepted to get higher throughput (probably
50% of the select statements done in my largest system use the read
uncommitted isolation level)

In theory, all tables should be at least 3rd normal form of Boyce-Codd
normal form. In reality, you will get tables that are intentionally in 1st
or 2nd normal form.

Post a reply to this message

"Orchid XP v7" <voi### [at] devnull> wrote in message
news:4766a720@news.povray.org...

> Personally I prefer Oracle's lockless multiversion system - although
> obviously that has its own set of drawbacks.

oh, btw, Oracle also uses locks.
http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/consist.htm#i
5704

Post a reply to this message

Orchid XP v7 wrote:
> I just object to being told I know nothing about databases when actually 
> I do. I don't claim to be a world-renound expert, but I do know 
> *something*.

Nobody is claiming you know nothing. We're just claiming that you're 
making incorrect claims about database systems that are easily checked, 
and then basing vehement opinions on said incorrect information.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Jim Henderson wrote:
> My point here is that he's actually stood up and said "now wait just a 
> damned minute" - something that he has needed to do for a while.

Does that make him a triffid? ;-)

> So I still say "well done!"

True. :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

Post a reply to this message

Gail Shaw wrote:
> In theory, you want to prevent any form of data anomaly from multiple
> accesses. 

Or, in my examples, you only have one writer, and that writer is doing 
atomic writes, and no reader looks at multiple records in one 
transaction. So what's there to transactionify?

I have another table, where I have multiple processes going thru it, 
doing what it says to do, each step taking maybe 10-30 seconds. Rather 
than using a transactional table, I do things like
SELECT * from to_do where state = 3 limit 10
then for each of those rows, I do
UPDATE to_do SET state=4 WHERE id=$id AND state = 3
then I check if the num_rows_affected > 0, and if so, I know I'm the one 
that changed that row.  Just as an example. If the rows affected was 
zero, someone else changed that specific ID.

A bit kludgey, I'll admit, but better than holding a transactional lock 
on the table for 30 seconds at a time.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Orchid XP v7 wrote:
> I see. So thinking that transactions matter is "far-out" and "visibly 
> ingorant"?

No. Insisting that MySql is a toy that doesn't have them, even after 
being told your information is long out of date, is "visibly ignorant".  :-)

> Um... I did? [At least, I read the MySQL manual, and spent some time 
> using it.]

And you missed the part about multiple users and the "Begin transaction" 
statement?

> When somebody says "oh yeah, transactions aren't really all that 
> important" 

We said "they're not always important", not that they're not really 
important.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Orchid XP v7 wrote:
> Personally I prefer Oracle's lockless multiversion system - although 
> obviously that has its own set of drawbacks.

There's also optimistic locking. I think MySql implements a number of 
these techniques, depending on what you ask for. There are anumber of 
levels of isolation in standard sql, which mysql implement.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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"Darren New" <dne### [at] sanrrcom> wrote in message
news:4766e906@news.povray.org...
> Gail Shaw wrote:
> > In theory, you want to prevent any form of data anomaly from multiple
> > accesses.
>
> Or, in my examples, you only have one writer, and that writer is doing
> atomic writes, and no reader looks at multiple records in one
> transaction. So what's there to transactionify?

Similar to what I have. My main system, most of the data changes are done
during the overnight processes. Hence, doing most of the reads uncommited is
safe. I don't need to go for read committed. I certainly don't need
serialisable.

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Darren New wrote:

> Or, in my examples, you only have one writer

I missed the part that there was exactly 1 writer. I thought you were 
just saying that you only ever write to one end of the table. [This 
condition alone obviously doesn't preclude Bad Things.]

> A bit kludgey, I'll admit, but better than holding a transactional lock 
> on the table for 30 seconds at a time.

Which is why I prefer Oracle's lock-free approach. But let's not start a 
flamewar about that too...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Gail Shaw wrote:

> Yup. You know the theory.

Well, and the practice of backing up and restoring a production 
database. But really, that's not especially hard if everything has been 
configured right... [You just need to DAMN WELL make sure you can do it 
in your sleep though.]

> In practice however things are sometimes done
> differently. Not because theory is wrong, but because sometimes shortcuts
> are necessary.

This part I understand.

> In theory, you want to prevent any form of data anomaly from multiple
> accesses. In reality, that often reduces concurrency to unacceptable levels,
> so some possible anomolies are accepted to get higher throughput.

Hence the various transaction isolation levels we spent so much time 
numbing our brains with, I take it...

Never came across anybody arguing that we should go for the very lowest 
option though. (Usually more like "the top option is best, but the one 
just below it is very much faster with only a couple of drawbacks"...)

> In theory, all tables should be at least 3rd normal form of Boyce-Codd
> normal form. In reality, you will get tables that are intentionally in 1st
> or 2nd normal form.

"Flexing the model?"

As in, use the theory, work out the theoretically ideal configuration, 
and then denormalise from there, making a note of what extra hoops you 
have to jump through with each denormalisation step and making sure the 
payoff is worth it. Is the way they taught us anyway... we never 
actually got as far as doing that in practice.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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Orchid XP v7 wrote:
> I missed the part that there was exactly 1 writer.

Well, depends on the table. There's a few that get real-time data feeds 
from exactly one supplier. There are others that everyone writes to, but 
each writer has its own keyspace (such as the table that stores all the 
debugging output, keyed by host name, PID, and timestamp).

> I thought you were 
> just saying that you only ever write to one end of the table. [This 
> condition alone obviously doesn't preclude Bad Things.]

If nobody overwrites anything, then yes, everyone is by definition 
writing to the "end" of the table. (Appending to the table, that is.)

>> A bit kludgey, I'll admit, but better than holding a transactional 
>> lock on the table for 30 seconds at a time.
> 
> Which is why I prefer Oracle's lock-free approach. But let's not start a 
> flamewar about that too...

Well, this is optimistic locking, performed manually. :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Orchid XP v7 nous apporta ses lumieres en ce 2007/12/17 11:27:
> Tom Galvin wrote:
> 
>> Why reinvent the wheel?
> 
> I was hoping that if I make it simple enough, it will be impossible to 
> misconfigure it. ;-)
> 
The simplest programm that can have any configuration *CAN* be misconfigured! No 
mather what trap you implement, what failsafe you place, what sanity check you 
build, there is some genial idiot that will find a way to screw things...

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you have ever "Hand-Coded" a 
bezier patch.
Stephan Ahonen

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Orchid XP v7 wrote:
> Gilles Tran wrote:
>> How difficult it is to actually listen to what professionals like 
>> Darren and Tom and Gail are telling you?
> 
> When somebody says "oh yeah, transactions aren't really all that 
> important" when I spent 4 months learning about how important 
> transactions are, I have to think "hmm, who is right here?"
> 


I am.


It's a helpdesk.  It's not for 10,000 employees at Microsoft, GM, NASA, 
or for members of Parliament.  It will not hold company financial 
information, or vital medical records during an epidemic, or operations 
at a nuclear power plant.  KISS, and don't reinvent the wheel.

Post a reply to this message

Orchid XP v7 wrote:
> Tom Galvin wrote:
> 
>> Why reinvent the wheel?
> 
> I was hoping that if I make it simple enough, it will be impossible to 
> misconfigure it. ;-)
> 

Why do you lie right to my face.  You know that's not possible.  You 
want to play.  Admit it.

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Alain <ele### [at] netscapenet> wrote:
....
> The simplest programm that can have any configuration *CAN* be misconfigured! No
> mather what trap you implement, what failsafe you place, what sanity check you
> build, there is some genial idiot that will find a way to screw things...

The most valuable programming course I have ever taken was taught by one Dr.
Breckenridge, who was justifiably notorious for the difficulty of his exams.
He did, however, give us one small break. A full five percentage points was
added to the score of any test paper with the following written verbatim at the
top:

"The statement: 'No one could possibly be that stupid,' is universally false."

Best Regards,
Mike C.

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On Mon, 17 Dec 2007 13:19:51 -0800, Darren New wrote:

> Jim Henderson wrote:
>> My point here is that he's actually stood up and said "now wait just a
>> damned minute" - something that he has needed to do for a while.
> 
> Does that make him a triffid? ;-)

LOL!  Is he planted?

Jim

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Mike the Elder nous apporta ses lumieres en ce 2007/12/18 09:08:
> Alain <ele### [at] netscapenet> wrote:
> ....
>> The simplest programm that can have any configuration *CAN* be misconfigured! No
>> mather what trap you implement, what failsafe you place, what sanity check you
>> build, there is some genial idiot that will find a way to screw things...
> 
> The most valuable programming course I have ever taken was taught by one Dr.
> Breckenridge, who was justifiably notorious for the difficulty of his exams.
> He did, however, give us one small break. A full five percentage points was
> added to the score of any test paper with the following written verbatim at the
> top:
> 
> "The statement: 'No one could possibly be that stupid,' is universally false."
> 
> Best Regards,
> Mike C.
> 
> 
In a programing course, the teacher asked for a program where all input was 
filtered to reject invalid entry. One student came up with his solution saying 
that his filtering was foolproof. The teacher, without ever looking, slamed his 
fingers across the keyboard and hit the return key. Instant crash! The program 
was expecting a numerical value faling within a given range. It filtered a 
numerical entry against that range. It was unable to cope with alphanumeric entry.

-- 
Alain
-------------------------------------------------
   A hooker once told me she had a headache.
   	Rodney Dangerfield

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