Karim Nassar <karim(dot)nassar(at)NAU(dot)EDU> writes:
>> Look at what your triggers are doing. My private bet is that you have
>> unindexed foreign keys referencing this table, and so each deletion
>> forces a seqscan of some other, evidently very large, table(s).
> Almost. I have a large table (6.3 million rows) with a foreign key
> reference to this one (which has 749 rows), however it is indexed.
In that case there's a datatype mismatch between the referencing and
referenced columns, which prevents the index from being used for the
FK check.
regards, tom lane