On Feb 3, 2008 11:14 PM, Alex Turner <[EMAIL PROTECTED]> wrote:
> I"m not a database expert, but wouldn't
>
> create table attribute (
> attribute_id int
> attribute text
> )
>
> create table value (
> value_id int
> value text
> )
>
> create table attribute_value (
>entity_id int
> a
In article <[EMAIL PROTECTED]>,
Alex Turner <[EMAIL PROTECTED]> wrote:
%
% I"m not a database expert, but wouldn't
%
% create table attribute (
% attribute_id int
% attribute text
% )
%
% create table value (
% value_id int
% value text
% )
%
% create table attribute_value (
% entity_
On Feb 5, 2008, at 10:17 AM, Alex Turner wrote:
On Feb 4, 2008 7:09 AM, Scott Marlowe <[EMAIL PROTECTED]> wrote:
On Feb 3, 2008 10:14 PM, Alex Turner <[EMAIL PROTECTED]> wrote:
I"m not a database expert, but wouldn't
create table attribute (
attribute_id int
attribute text
)
create tabl
I just thought of another problem, the system can have multiple values
for a single attribute. How do you normalise that without basically
adding a link table that's just the same thing as given below (I know
there are array types in Postgresql, but there aren't in other DBs and
I'm a fan of keepi
That is a very awesome system. I am constantly impressed at the
awesomeness of Postgresql.
Alex
On Feb 4, 2008 1:06 PM, Tom Lane <[EMAIL PROTECTED]> wrote:
> Jorge Godoy <[EMAIL PROTECTED]> writes:
> > Em Monday 04 February 2008 07:03:47 Dawid Kuroczko escreveu:
> >> Well, but PostgreSQL's NULLs
How do you normalize 90 arbitrary attributes away into subordinate tables?
There will still be 90 of them, you can split them up into multiple tables,
but it would just make joins a pain and potentially bog down the query
planner I would think.
Alex
On Feb 4, 2008 7:09 AM, Scott Marlowe <[EMAIL P
Jorge Godoy <[EMAIL PROTECTED]> writes:
> Em Monday 04 February 2008 07:03:47 Dawid Kuroczko escreveu:
>> Well, but PostgreSQL's NULLs occupy almost no space, or rather a bit of
>> space, that is one bit exactly. ;-) I am pretty much sure that
>> storage-wise looking NULLs
>> are more efficient.
On Mon, Feb 04, 2008 at 10:49:51AM +0100, Masse Jacques wrote:
> Hello
[much garbage including HTML trimmed.]
Please set your mail client to text-only. HTML does not make your
point better, and it annoys the heck out of people whose mail readers
use text.
> This model is known as Entity-Value-A
"Scott Marlowe" <[EMAIL PROTECTED]> writes:
> On Feb 3, 2008 10:14 PM, Alex Turner <[EMAIL PROTECTED]> wrote:
>
>> give you a lot less pages to load than building a table with say 90 columns
>> in it that are all null, which would result in better rather than worse
>> performance?
Fwiw Postgres
On Sat, 2 Feb 2008 09:45:57 -0800
David Fetter <[EMAIL PROTECTED]> wrote:
> On Sat, Feb 02, 2008 at 01:38:19PM +0100, Thomas Pundt wrote:
> > Hi,
> >
> > vladimir konrad wrote:
> >> I think that I understand basic relational theory but
>
> Clearly, you'll have to revisit that thought.
>
> > [exa
On Feb 3, 2008 10:14 PM, Alex Turner <[EMAIL PROTECTED]> wrote:
> I"m not a database expert, but wouldn't
>
> create table attribute (
> attribute_id int
> attribute text
> )
>
> create table value (
> value_id int
> value text
> )
>
> create table attribute_value (
>entity_id int
> a
Em Monday 04 February 2008 07:03:47 Dawid Kuroczko escreveu:
> On Feb 4, 2008 5:14 AM, Alex Turner <[EMAIL PROTECTED]> wrote:
> > I"m not a database expert, but wouldn't
>
> [...]
>
> > give you a lot less pages to load than building a table with say 90
> > columns in it that are all null, which w
On Feb 4, 2008 5:14 AM, Alex Turner <[EMAIL PROTECTED]> wrote:
> I"m not a database expert, but wouldn't
>
[...]
>
> give you a lot less pages to load than building a table with say 90 columns
> in it that are all null, which would result in better rather than worse
> performance?
Well, but Postg
] "advanced" database design (long)
I"m not a database expert, but wouldn't
create table attribute (
attribute_id int
attribute text
)
create table value (
value_id int
I"m not a database expert, but wouldn't
create table attribute (
attribute_id int
attribute text
)
create table value (
value_id int
value text
)
create table attribute_value (
entity_id int
attribute_id int
value_id int
)
give you a lot less pages to load than building a table w
vladimir konrad wrote:
Worst case would be another column flagging the test type.
Why do you think this is the worst case?
Bad choice of words - just referring to using the where clause to
extract one particular test - if that is insufficient you can use a test
column to track what test i
Hello, and thanks
> Are the tests that different that you need to segregate the data?
> I see them both as being the time taken to travel a distance. The
> only difference is whether the time or distance is used to end the
> measurement.
Good point (I have realised this after posting, when I dug
vladimir konrad wrote:
The system I am developing has to handle "tests" (for rowing athletes):
1. how many meters athlete did in 10 minutes (result is float)
2. how long it took the athlete to do 5 kilo-meters (the result is time)
So it looks that I need table for each of 1 and 2 (because of di
Hello,
>> vladimir konrad wrote:
>>> I think that I understand basic relational theory but
> Clearly, you'll have to revisit that thought.
Usually I have one table per "entity" modelled (and the table holds
fields describing that entity).
E.g. subject would have name fields and date of bir
David Fetter wrote:
> The math beneath this is that query complexity goes up like O(E!A!V!)
> for Entity, Attribute and Value.
Makes sense.
> The first price, though, and by far the biggest, is that it's
> impossible to maintain any kind of data integrity in such a system, as
> such constraints,
> If you have some part of your app that needs to "select" the list of
> columns in a table you should look at
> http://www.postgresql.org/docs/8.2/interactive/catalogs.html
> particularly pg_class and pg_attribute
Thanks, this could come handy.
Vlad
---(end of broadcast
Lewis Cunningham wrote:
--- vladimir konrad <[EMAIL PROTECTED]> wrote:
I think that I understand basic relational theory but then I had an
idea.
Basically, instead of adding field to a table every time there is a
need for it, have a table split in two: one holds identity (id) and
one holds t
On Sat, Feb 02, 2008 at 01:38:19PM +0100, Thomas Pundt wrote:
> Hi,
>
> vladimir konrad wrote:
>> I think that I understand basic relational theory but
Clearly, you'll have to revisit that thought.
> [example stripped]
>
> Yes, this is known as eg. Entity-Attribute-Value model (cf.
> wikipedia).
> Basically, you would be creating your own data dictionary (i.e.
> system catalog) on top of the db data dictionary. The database
> already comes with a way to easily add columns: ddl. I have seen
> newbie database designers reinvent this method a hundred times. The
> performance hits and compl
vladimir konrad <[EMAIL PROTECTED]> wrote:
>
> Hello,
>
> I think that I understand basic relational theory but then I had an
> idea. What I would like to know if this is sometimes done or that I am
> possibly mad... Also, I do not know the terminology for this kind of
> thing so I do not know whe
--- vladimir konrad <[EMAIL PROTECTED]> wrote:
> I think that I understand basic relational theory but then I had an
> idea.
> Basically, instead of adding field to a table every time there is a
> need for it, have a table split in two: one holds identity (id) and
> one holds the attributes (li
> Yes, this is known as eg. Entity-Attribute-Value model (cf.
> wikipedia).
Thank you for the pointer and term. This will get me started.
> IMO most times its disadvantages (it can be very hard to write
> performant queries compared to the traditional row based model) weigh
> higher than you gain
Hi,
vladimir konrad wrote:
I think that I understand basic relational theory but then I had an
idea. What I would like to know if this is sometimes done or that I am
possibly mad... Also, I do not know the terminology for this kind of
thing so I do not know where and what to look for.
Basically
Hello,
I think that I understand basic relational theory but then I had an
idea. What I would like to know if this is sometimes done or that I am
possibly mad... Also, I do not know the terminology for this kind of
thing so I do not know where and what to look for.
Basically, instead of adding f
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