On Feb 18, 2010, at 11:55 AM, Manlio Perillo wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Michael Bayer ha scritto: >> [...] >>> so what I had in mind is that, if its given a join as the left side, >>> it just does the "natural" thing, i.e. joins to the right. >>> If the "natural" join isn't available, then it does its usual >>> search through the whole thing. > > What do you mean by "natural join isn't available"? > There is no direct foreign key relationship between the left and the > right side of the join?
yes. > >> >>> I think _match_primaries could, right before it raises its message, > > Since we are speaking about _match_primaries, I'm curious to know why > the implementation is: > > def _match_primaries(self, primary, secondary): > global sql_util > if not sql_util: > from sqlalchemy.sql import util as sql_util > return sql_util.join_condition(primary, secondary) > > What is the need for a sql_util to be global? that pattern is used when there is a circular module import between two modules. the global + boolean is to avoid repeated calls to "import". > >>> just ask "well is this particular foreign key the rightmost join on >>> the left side" and then its good. >> > > Non sure to understand what you have in mind, here. > > Do you mean that the checks: > `if len(crit) == 0` and `len(constraints) > 1` should not be done by the > util.join_condition, and instead: > > 1) `_match_primaries` method will call `util.join_condition`, using the > rightmost join on the left side (as in my patch) > 2) if len(crit) == 0, then it will call `util.join_condition` again, but > this time using the left side of the join, as is that is pretty much what I mean. if the left side is a join, then call join_condition with the rightmost side of the left first, if nothing returned, call with the full left side. > > ? > > >>> to get non-default behavior, as always you'd specify the on clause. >>> which you'd have to do anyway even without the natural feature if you >>> wanted to join....unnaturally. >> > > Manlio > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.10 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > > iEYEARECAAYFAkt9cOYACgkQscQJ24LbaUSS7QCeMchE6p2t3WaHDJzH+dTAu2Xk > BBUAmQHpDq8Naq9f4cWsolK9BRnjTBcf > =UAU4 > -----END PGP SIGNATURE----- > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
