Re: Need schema design advice

[Ben Chobot <bench@xxxxxxxxxxxxxxx>]

On Oct 12, 2008, at 5:51 PM, Martin Gainty wrote:

could you provide a brief explanation of EAV ?

Instead of:

create table vehicles

(

kind text primary key,

wheels int

);

insert into vehicles (kind, wheels) values ('car',4);

insert into vehicles (kind, wheels) values ('bike',2);

create table boats

(

kind text primary key,

displacement int

);

insert into boats (kind,displacement) values ('small boat',1000);

insert into boats (kind,displacement) values ('big boat',300000);

... in an EAV model you would do something like:

create table eav

(

kind text primary key,

attr text,

value text

);

insert into eav (kind, attr, value) values ('car','wheels','4');

insert into eav (kind, attr, value) values ('bike','wheels','2');

insert into eav (kind, attr, value) values ('small boat','displacement','1000');

insert into eav (kind, attr, value) values ('big boat','displacement','300000');