def pk_and_sequence_for(table)
result = query( SELECT attr.attname, seq.relname FROM pg_class seq, pg_attribute attr, pg_depend dep, pg_constraint cons WHERE seq.oid = dep.objid AND seq.relkind = 'S' AND attr.attrelid = dep.refobjid AND attr.attnum = dep.refobjsubid AND attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1] AND cons.contype = 'p' AND dep.refobjid = '#{quote_table_name(table)}'::regclass, 'SCHEMA')[0]
if result.nil? or result.empty?
result = query( SELECT attr.attname, CASE WHEN pg_get_expr(def.adbin, def.adrelid) !~* 'nextval' THEN NULL WHEN split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2) ~ '.' THEN substr(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2), strpos(split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2), '.')+1) ELSE split_part(pg_get_expr(def.adbin, def.adrelid), '''', 2) END FROM pg_class t JOIN pg_attribute attr ON (t.oid = attrelid) JOIN pg_attrdef def ON (adrelid = attrelid AND adnum = attnum) JOIN pg_constraint cons ON (conrelid = adrelid AND adnum = conkey[1]) WHERE t.oid = '#{quote_table_name(table)}'::regclass AND cons.contype = 'p' AND pg_get_expr(def.adbin, def.adrelid) ~* 'nextval|uuid_generate', 'SCHEMA')[0]
end
[result.first, result.last]
rescue
nil
end