If you have tables
B has a foreign key referencing
A, then trying to truncate
A will result in something like this:
> truncate A; ERROR: cannot truncate a table referenced in a foreign key constraint
truncate has some tricks up its sleeve.
If you know two tables are tied together via a foreign key constraint, you can just truncate both of them at once:
> truncate A, B; TRUNCATE TABLE;
If many tables are tied together in this way and you are looking to throw all of it out, then a simpler approach is to cascade the truncation:
> truncate A cascade; NOTICE: truncate cascades to table "B" TRUNCATE TABLE
Use these with care and potentially within transactions because your data will go bye bye.