> Maybe odd, but simpler to optimize this way. > > Your idea would be also a very good optimization, there was > already a discussion about that here: > http://archives.postgresql.org/pgsql-performance/2006-01/msg00 > 151.php, but that time Tom refused it because it was too > expensive and rare. Maybe now he has a different opinion. > However, left join optimization is lot simpler and cheaper, > and can be useful not only for O/R mappers, but for efficient > vertical partitioning as Simon mentioned.
For the views use case there is a simple solution without the expensive optimization: If you have a PK FK relationship simply rewrite the view to use a left join instead of a join. Since there is always one row on the outer (PK) side it makes no difference to the result set. And then the left join optimization can be used. Andreas ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
