Re: [GENERAL] Need schema design advice

[Ben Chobot]

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');