[PostgreSQL] clean should remove views

[c410-f3r]

See #5

[zacck-zz]

@c410-f3r Going to try implementing this one, shall we use the flyaway implementation as well?

[c410-f3r]

@zacck Sure! Feel free to work on this issue.

You can create your own view query selection but yeah, it is probably easier to just look into the flyway implementation. Something like:

SELECT relname AS generic_column FROM pg_catalog.pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace LEFT JOIN pg_depend dep ON dep.objid = c.oid AND dep.deptype = 'e' WHERE c.relkind = 'v' AND  n.nspname = '{schema}' AND dep.objid IS NULL

[zacck-zz]

@c410-f3r I can't seem to understand the SQL operation above would you care to explain it?

[zacck-zz]

Aha I see, this searches for views which we can then drop!