Re: optimization for repeated values within JOINs

Bill Schneider wrote:

> Does the PostgreSQL JDBC driver/protocol perform any optimization for 
> repeated values created by joins?

No. The existing protocol is documented at 
http://www.postgresql.org/docs/8.0/static/protocol.html

> Has anyone else thought about this, or does it just not affect 
> performance enough to matter?

pgsql-hackers is probably the place to discuss it.

> select a.id, a.longText, b.id
>   from a join b on b.a_id = a.id
>   order by a.id; 

In this case, you could of course turn it into two separate queries when 
you know the characteristics of the query make that a win. It seems like 
a lot of work for marginal benefit to try to do some sort of 
duplicate-elimination automatically in the protocol.

-O