Migration-only method

        Notes:
            Precondition: buid cache must be disabled

async def _storBuidSet(self, oper):
        '''
        Migration-only method

        Notes:
            Precondition: buid cache must be disabled
        '''
        assert self.buidcache.disabled

        _, (form, oldb, newb) = oper

        fenc = form.encode() + b'\x00'

        pvoldval = s_msgpack.en((oldb,))
        pvnewval = s_msgpack.en((newb,))

        for lkey, lval in self.layrslab.scanByPref(oldb, db=self.bybuid):

            proputf8 = lkey[32:]
            valu, indx = s_msgpack.un(lval)

            if indx is not None:

                # <prop><00><indx>
                propindx = proputf8 + b'\x00' + indx

                if proputf8[0] in (46, 35): # ".univ" or "#tag"
                    self.layrslab.put(propindx, pvnewval, dupdata=True, db=self.byuniv)
                    self.layrslab.delete(propindx, pvoldval, db=self.byuniv)

                bypropkey = fenc + propindx

                self.layrslab.put(bypropkey, pvnewval, db=self.byprop)
                self.layrslab.delete(bypropkey, pvoldval, db=self.byprop)

            self.layrslab.put(newb + proputf8, lval, db=self.bybuid)
            self.layrslab.delete(lkey, db=self.bybuid)