Re: [OT] Inventory systems (private) - Mailing list pgsql-sql

Ries,

Sorry I missed a few days here. I was busy elsewhere.

Anyway, the speed issue is fixed with indexes. Once you know
the kind of queries you will be making, create an optimized index for 
each one of those queries.

You probably want to have a separate table for storing 
the attribute names. I.e. instead of using a text variable
in each record, use a unique id which references an entry
in an attributes table. This won't affect the speed of the
system but it will save some space. Or if nothing else, it will
be more elegant.


Cheers,

Troy

> 
> Troy, Andy,
> 
> you both are right and it was my first tought. My only concern is that would
> this system be fast enough for large tables (for me large is around 250.000
> unique items) and thus my attribute table would be around 2.500.000 and
> 5.000.000 entrys. A record for one attribute is small I think around 128
> byte in size.
> 
> One thing is that every attribute must be in it's own domain. For weight for
> example I have three different meanings ( 1] Pull weight 2] push weight 3]
> weight of the items itself) but using the method troy suggested that would
> not be a problem if I create some sort of a domain table.
> 
> Anyway so far thangs for the quick responses, I've got something to work on.
> 
> best regards,
> Ries van Twisk
> 
> 
> 
> 
> -----Oorspronkelijk bericht-----
> Van: Troy [mailto:tjk@tksoft.com]
> Verzonden: dinsdag 3 december 2002 15:47
> Aan: Ries van Twisk
> CC: pgsql-sql@postgresql.org
> Onderwerp: Re: [SQL] [OT] Inventory systems (private)
> 
> 
> Ries,
> 
> One solution is to create a table such as follows:
> 
> CREATE TABLE inventory (id serial, product text,
>     PRIMARY KEY (id)
> ) ;
> CREATE TABLE attributes (prodid int4, textkey text, textvalue text,
> int4value int4,
>     FOREIGN KEY (prodid) REFERENCES inventory (id) MATCH FULL ON DELETE CASCADE
> ON UPDATE CASCADE
> );
> 
> INSERT INTO inventory (id, product) VALUES (100, 'Tire');
> 
> INSERT INTO attributes (prodid, textkey, textvalue) VALUES (100, 'Type',
> 'matchbox tire');
> INSERT INTO attributes (prodid, textkey, textvalue) VALUES (100, 'Color',
> 'black');
> INSERT INTO attributes (prodid, textkey, int4value, textvalue) VALUES (100,
> 'Diameter', 12, 'mm');
> INSERT INTO attributes (prodid, textkey, int4value, textvalue) VALUES (100,
> 'Weight', 20, 'g');
> CREATE INDEX textkeys ON attributes USING btree (prodid);
> CREATE INDEX textkeys2 ON attributes USING btree (prodid,textkey);
> 
> To select diameter for product id 100 (Tire):
> SELECT prodid FROM attributes WHERE prodid = 100 AND textkey = 'Diameter';
> 
> To select several:
> SELECT prodid,textkey,textvalue,int4value FROM attributes WHERE prodid = 100
> AND textkey IN ('Diameter', 'Weight', 'Color', 'Type');
> 
> 
> and so on.
> 
> The indexes are just a fast guess. You would need to look at the queries
> you generate and decide which indexes are needed.
> 
> 
> 
> Cheers,
> 
> 
> Troy
> 
> Troy Korjuslommi                Tksoft Inc.
> tjk@tksoft.com
> 
> 
> 
> 
> >
> > Hi All,
> >
> > is there any whitepaper, document or website that can point me to how to
> > setup a inventory system?
> > I'm particulary interested how other people solve the problem of a unknown
> > number of attributes to a inventory item.
> >
> > example:
> > BAL                <-- Inventory Item
> >     - Color      <- Attribute
> >     - Diameter   <- Attribute
> >     - Weight     <- Attribute
> >
> > Car                <-- Inventory Item
> >     - Speed      <- Attribute
> >     - Size       <- Attribute
> >     - Weight     <- Attribute
> >     - Color      <- Attribute
> >
> > Computer                <-- Inventory Item
> >     - Brand           <- Attribute
> >     - Weight          <- Attribute
> >     - Windows/Linux   <- Attribute
> >
> >
> > I can ofcource add any number of columns to a table but for a lot of items
> > there will be a lot of NULL values and currently I don't know how many
> > attrubutes one item can have (possible between 10 and 20). This can even
> > change in feature opon request.
> >
> > Ries
> >
> >
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> >
> 
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