On 06/09/2014 07:13 PM, Andres Freund wrote: > On 2014-06-09 13:42:22 +0200, Vik Fearing wrote: >> On 06/09/2014 09:06 AM, Gavin Flower wrote: >>> From memory all unique keys can be considered 'candidate primary keys', >>> but only one can be designated 'the PRIMARY KEY'. >> >> Almost. Candidate keys are also NOT NULL. > > The list actually is a bit longer. They also cannot be partial.
What? AFAIK, that only applies to an index. How can the data itself be partial? > There's generally also the restriction that for some contexts - like > e.g. foreign keys - primary/candidate keys may not be deferrable.. Again, what is deferrable data? -- Vik -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
