That sounds reasonable too.
On Mon, Apr 11, 2016 at 05:41:57AM +0000, Elluru, Krishna Mohan wrote: > Hi Ben, > If the below idea of allowing NULL values for Indexed columns makes > sense., shall we add an attribute (allow_null_index = false kind) as an > optional parameter for such type of columns and ensure compatibility with > existing/old schema? Does it sound okay? > > Thanks > Krishna Mohan > > -----Original Message----- > From: Ben Pfaff [mailto:b...@ovn.org] > Sent: Monday, April 11, 2016 11:00 AM > To: Ansari, Shad <shad.ans...@hpe.com> > Cc: Elluru, Krishna Mohan <elluru.kri.mo...@hpe.com>; dev@openvswitch.org > Subject: Re: [ovs-dev] [PATCH] ovsdb: Force columns that contain weak > references to be immutable. > > On Mon, Apr 04, 2016 at 10:38:40PM +0000, Ansari, Shad wrote: > > > > > > HI Ben, > > > How does column which is weak reference and also configured as an > > > Index? If it is mutable, and the corresponding UUID going > > > away(deletion of record) leaves column value as NULL right? And what > > > would be the behavior if the table is a Root table also? > > > I am listing down, my assumptions: > > > > > > 1. In table X, If the column is index and a weak reference to table > > > y, on table y row deletion, the index field would become NULL and > > > since it is an index, constraint violation would occur and to avoid, > > > it is expected to remove the row first in table X and table Y row > > > deletion can happen in same txn or consequent transactions. Correct? > > > 2. If the table X is also a root table, and one of its column is an > > > index and weak reference to table Y, on row deletion in table Y, > > > constraint violation would occur, hence similar to above table X row > > > cleanup is expected to happen prior to table Y row deletion. > > > > > > If above 2 statements is true, index with weak reference is > > > becoming equivalent to strong reference. Am I correct? > > > > > > Thanks > > > Krishna Mohan > > > > Would it make sense to allow NULL values for columns that are references > > and indexes. Something like what MySQL allows for unique keys. > > > > http://dev.mysql.com/doc/refman/5.0/en/create-index.html > > That's a reasonable idea. It could theoretically break some currently > working use cases, if someone has an OVSDB schema that relies on an index to > ensure the uniqueness of an empty column. I don't know whether there are > schemas out there that rely on this property. > > I don't know how this idea would extend to multi-column indexes. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
