The unique constraint probably could be broken during the execution. For example, Probe-cache requires at most one row returned per probe and a violation could mean more than one row is returned. Currently, the cache is not built for such condition.
Thanks --Qifan On Tue, Feb 2, 2016 at 4:09 PM, Eric Owhadi <[email protected]> wrote: > Can you elaborate on this? > As I understand Suresh message, even with NULLABLE columns, we still assume > uniqueness of the concatenation of all column making up the PK. > So your sentence "a full PK will map to up to one row" is still respected? > Or am I misunderstanding? > Eric > > -----Original Message----- > From: Qifan Chen [mailto:[email protected]] > Sent: Tuesday, February 2, 2016 4:05 PM > To: dev <[email protected]> > Subject: Re: [DISCUSS] Change the default setting of > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > Allowing NULL in primary key columns could break some existing assumptions > in our code base on PKs. For example, a full PK will map to up to one row, > which is a logic constraint that the compiler takes full advantage of. > > Thanks --Qifan > > On Tue, Feb 2, 2016 at 4:01 PM, Dave Birdsall <[email protected]> > wrote: > > > ANSI in general does not concern itself with physical issues. So no > > partitioning, no indexing, and so on in ANSI. > > > > > > -----Original Message----- > > From: Eric Owhadi [mailto:[email protected]] > > Sent: Tuesday, February 2, 2016 1:59 PM > > To: [email protected] > > Subject: RE: [DISCUSS] Change the default setting of > > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > > > Great, so my 2 cts is that we should not worry about ANSI on the > > default not supporting NULL, since ANSI did not account for > > partitioning... > > Eric > > > > -----Original Message----- > > From: Roberta Marton [mailto:[email protected]] > > Sent: Tuesday, February 2, 2016 3:55 PM > > To: [email protected] > > Subject: RE: [DISCUSS] Change the default setting of > > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > > > Store by is not ANSI standard. > > > > Roberta > > > > -----Original Message----- > > From: Eric Owhadi [mailto:[email protected]] > > Sent: Tuesday, February 2, 2016 1:53 PM > > To: [email protected] > > Subject: RE: [DISCUSS] Change the default setting of > > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > > > Do you happen to know if STORE BY is part of the ANSI standard, and if > > ANSI mandate that anything in STORE BY must be part of the PK? > > Eric > > > > -----Original Message----- > > From: Dave Birdsall [mailto:[email protected]] > > Sent: Tuesday, February 2, 2016 3:45 PM > > To: [email protected] > > Subject: RE: [DISCUSS] Change the default setting of > > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > > > Our default behavior would not be ANSI standard if this is changed. I > > don’t know if that is a compelling reason not to do this though. > > > > Dave > > > > -----Original Message----- > > From: Suresh Subbiah [mailto:[email protected]] > > Sent: Tuesday, February 2, 2016 1:37 PM > > To: [email protected] > > Subject: [DISCUSS] Change the default setting of > > ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON > > > > Hi, > > > > Do you foresee potential problems if we change the default setting > > for ALLOW_NULLABLE_UNIQUE_KEY_CONSTRAINT to ON. ? > > It does seem that users are asking for using and setting this CQD in > > their individual applications. > > Other than JIRA 1801, there are no known issues when this attribute is > > set to ON. > > Having the default set to ON could make Trafodion easier to use. > > > > I can file a JIRA if there is agreement or if we think the discussion > > should be moved to a JIRA. > > > > Thank you > > Suresh > > > > > > -- > Regards, --Qifan > -- Regards, --Qifan
