"Florian G. Pflug" <fgp@xxxxxxxx> writes:
> when deleting a lot of rows from a large table - and each time it has to find
> referencing tuples by doing an index scan
Are you sure it was even an index scan? And not doing a sequential table scan
for every deletion? In order to do an index scan you need an index on foreign
key columns in the referencing tables, not just the referenced tables. Usually
people only think about the referenced tables because usually that's all they
need. Only when you start cascading updates and deletes do you need indexes on
the columns in the referencing tables.
--
greg
---------------------------(end of broadcast)---------------------------
TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
