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
