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Re: [Pharo-project] relational database and id field

by Benoit St-Jean

One more remark, Since you're storing objects into a RDBMS, I guess what you're trying to express into "the relational world" is a notion of pointer (such as an object contains a collection of something in one of its instance variable, or a child has a mother kinda relationship, link). In that case, to save you headaches and lots of "weird object-oriented modeling", an oid (object id) is what is used normally. Any sequence (the shorter the better, don't use GUID for instance!) would do... ----------------- Benoit St-Jean Yahoo! Messenger: bstjean A standpoint is an intellectual horizon of radius zero. (Albert Einstein) ________________________________ From: Alexandre Bergel <alexandre.bergel(a)me.com> To: Benoit St-Jean <bstjean(a)yahoo.com> Cc: Pharo-project(a)lists.gforge.inria.fr Sent: Thu, April 7, 2011 9:49:11 AM Subject: Re: [Pharo-project] relational database and id field > Normally, you should always have a primary key to uniquely identify a record in >a database table. If you have an attribute (or a set of attributes) that can >uniquely identify your ComicBook, you don't need an id field. BUT, if you tell >me you're going to store lots and lots and lots of those ComicBook instances, >having an id (integer) as the primary key has potential non-negligeable >advantages over, say, something like a name. Mainly because an id (let's >suppose it's an INT) takes way less storage than say a name (VARCHAR(30) for >instance) and thus more index records can fit into the key buffer in memory. Ok, I understand. > 1) yes, always provide a primary key > 2) if you have already A primary key (even a composite one) > 2a) if you need performance and are gonna store LOTS of those objects, the >smaller the key the better so you could create a surrogate key (the id key) >instead of using the "real" primary key > 2b) if performance is not an issue, you can use what is already available >that uniquely identifies your object (row) in the database table Thanks! > P.S. Are you using a particular OO-RDBMS framework? No, I am correcting a student thesis :-) I would probably not use SQL if I had to :-) Cheers, Alexandre > > ----------------- > Benoit St-Jean > Yahoo! Messenger: bstjean > A standpoint is an intellectual horizon of radius zero. > (Albert Einstein) > > > From: Alexandre Bergel <alexandre.bergel(a)me.com> > To: Pharo Development <Pharo-project(a)lists.gforge.inria.fr> > Sent: Thu, April 7, 2011 9:19:03 AM > Subject: [Pharo-project] relational database and id field > > Hi! > > Since there are some experts in databases here, I ask a general question about >it. > Assume that I have to use a relational database to store, let's stay instances >of Stef's ComicBook class. > Should the class ComicBook have a field id to uniquely identify a book? > > Cheers, > Alexandre > -- > _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: > Alexandre Bergel http://www.bergel.eu > ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. > > > > > > -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

April 7, 2011

Re: [Pharo-project] relational database and id field

by laurent laffont

On Thu, Apr 7, 2011 at 2:39 PM, laurent laffont <laurent.laffont(a)gmail.com>wrote: > On Thu, Apr 7, 2011 at 3:19 PM, Alexandre Bergel <alexandre.bergel(a)me.com>wrote: > >> Hi! >> >> Since there are some experts in databases here, I ask a general question >> about it. >> Assume that I have to use a relational database to store, let's stay >> instances of Stef's ComicBook class. >> Should the class ComicBook have a field id to uniquely identify a book? >> > > I always put an id field. All cases without id I've encountered were always > a pain. > > I don't have any argument against unique id. > > And if you are thinking about ISBN: - ISBN "should" be unique. In reality they're not. Because we communicate with software that have bugs. People who enter ISBN have bugs too. And when you mashup datas you always get soon or later 2 different documents with same ISBN. - documents edited before 1972 and not reedited after don't have ISBN. Laurent. > Laurent. > > > >> >> Cheers, >> Alexandre >> -- >> _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: >> Alexandre Bergel http://www.bergel.eu >> ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. >> >> >> >> >> >> >> >

April 7, 2011

Re: [Pharo-project] relational database and id field

by Henrik Sperre Johansen

On 07.04.2011 15:19, Alexandre Bergel wrote: > Hi! > > Since there are some experts in databases here, I ask a general question about it. > Assume that I have to use a relational database to store, let's stay instances of Stef's ComicBook class. > Should the class ComicBook have a field id to uniquely identify a book? > > Cheers, > Alexandre IANAE, but my definitive answer would be... Maybe. :) Depends on what other tables are in the database, their relationship with the ComicBook table,which you intend to query often, what you intend to query them for, etc. Cheers, Henry

April 7, 2011

Re: [Pharo-project] relational database and id field

by Benoit St-Jean

Hi Alexandre, Normally, you should always have a primary key to uniquely identify a record in a database table. If you have an attribute (or a set of attributes) that can uniquely identify your ComicBook, you don't need an id field. BUT, if you tell me you're going to store lots and lots and lots of those ComicBook instances, having an id (integer) as the primary key has potential non-negligeable advantages over, say, something like a name. Mainly because an id (let's suppose it's an INT) takes way less storage than say a name (VARCHAR(30) for instance) and thus more index records can fit into the key buffer in memory. To be brief 1) yes, always provide a primary key 2) if you have already A primary key (even a composite one) 2a) if you need performance and are gonna store LOTS of those objects, the smaller the key the better so you could create a surrogate key (the id key) instead of using the "real" primary key 2b) if performance is not an issue, you can use what is already available that uniquely identifies your object (row) in the database table P.S. Are you using a particular OO-RDBMS framework? ----------------- Benoit St-Jean Yahoo! Messenger: bstjean A standpoint is an intellectual horizon of radius zero. (Albert Einstein) ________________________________ From: Alexandre Bergel <alexandre.bergel(a)me.com> To: Pharo Development <Pharo-project(a)lists.gforge.inria.fr> Sent: Thu, April 7, 2011 9:19:03 AM Subject: [Pharo-project] relational database and id field Hi! Since there are some experts in databases here, I ask a general question about it. Assume that I have to use a relational database to store, let's stay instances of Stef's ComicBook class. Should the class ComicBook have a field id to uniquely identify a book? Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

April 7, 2011

Re: [Pharo-project] relational database and id field

by laurent laffont

On Thu, Apr 7, 2011 at 3:19 PM, Alexandre Bergel <alexandre.bergel(a)me.com>wrote: > Hi! > > Since there are some experts in databases here, I ask a general question > about it. > Assume that I have to use a relational database to store, let's stay > instances of Stef's ComicBook class. > Should the class ComicBook have a field id to uniquely identify a book? > I always put an id field. All cases without id I've encountered were always a pain. I don't have any argument against unique id. Laurent. > > Cheers, > Alexandre > -- > _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: > Alexandre Bergel http://www.bergel.eu > ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. > > > > > > >

April 7, 2011

[Pharo-project] Issue 3970 in pharo: Finder broken with last updates related to MorphTreeMorph

by pharo＠googlecode.com

Status: Accepted Owner: marcus.d...(a)gmail.com Labels: Milestone-1.3 New issue 3970 by marcus.d...(a)gmail.com: Finder broken with last updates related to MorphTreeMorph http://code.google.com/p/pharo/issues/detail?id=3970 Finder broken with last updates related to MorphTreeMorph

April 7, 2011

Re: [Pharo-project] relational database and id field

by Schwab,Wilhelm K

Expert? Certainly not me :) The question I will be waiting to see debated is whether you should "fabricate" an ID field (probably a counter), use ISBN or similar number, or use a compound key. FWIW, I invariably regret any decision I make in these areas, because there are tradeoffs. Relational databases are very good at what they do, which is storing tabular data and (most importantly) getting it back later; they are also a pain about it :( ________________________________________ From: pharo-project-bounces(a)lists.gforge.inria.fr [pharo-project-bounces(a)lists.gforge.inria.fr] On Behalf Of Alexandre Bergel [alexandre.bergel(a)me.com] Sent: Thursday, April 07, 2011 9:19 AM To: Pharo Development Subject: [Pharo-project] relational database and id field Hi! Since there are some experts in databases here, I ask a general question about it. Assume that I have to use a relational database to store, let's stay instances of Stef's ComicBook class. Should the class ComicBook have a field id to uniquely identify a book? Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.bergel.eu ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;.

April 7, 2011

Re: [Pharo-project] Import Package from VW to Pharo

by Nicolas Cellier

In Fileout30, don't use squeak output format but rather try VW30 output format. Nicolas 2011/4/6 Glenn Swanlund <glennswanlund(a)gmail.com>: > I have a package in VW7.6 that I want to move to Pharo (Windows 7). I tried > Fileout30 but could not get it to work. I was thinking of reading the .PST > file using the XML parser and then programmatically add classes and methods > to Pharo. I've looked at various classes related to Class and am having > difficulty getting started. Can anyone provide some pointers? > > Regards, > Glenn

April 7, 2011

Re: [Pharo-project] Issue 3849 in pharo: ExternalSettings should be cleaned

by pharo＠googlecode.com

Comment #1 on issue 3849 by marcus.d...(a)gmail.com: ExternalSettings should be cleaned http://code.google.com/p/pharo/issues/detail?id=3849 ExternalSettings as no clients anymore as of update #13135

April 7, 2011

[Pharo-project] [update 1.3] #13135

by Marcus Denker

13135 ----- Issue 3969: MorphTreeMorph performance Issue 3943: remove ExternalSettings from MC - clean left over temps compression code in CompiledMethod (as its in the Trailer for a long time) -- Marcus Denker -- http://www.marcusdenker.de INRIA Lille -- Nord Europe. Team RMoD.

April 7, 2011