On Tue, Nov 5, 2019 at 12:13:06PM -0500, Bruce Momjian wrote: > On Tue, Oct 29, 2019 at 02:00:38PM +0200, Tuomas Leikola wrote: > > On Thu, Oct 24, 2019 at 5:31 PM Bruce Momjian <br...@momjian.us> wrote: > > > > Uh, I am wondering if it is just too details for our docs. Can you > > think of some text and its location? > > > > > > > > "Unique indexes on functions can be used to create special types of > > constraints, like considering unique values equal (coalesce) or only > > allowing a > > single unique integer value of a float column (floor). A filtered unique > > index > > only enforces uniqueness on the subset of rows that match the filter." > > > > I guess this would append to the paragraph "When an index is declared > > unique, > > multiple table rows with equal indexed values are not allowed. Null values > > are > > not considered equal. A multicolumn unique index will only reject cases > > where > > all indexed columns are equal in multiple rows.". Links to the mentioned > > keywords and concepts would of course be helpful, but not strictly > > necessary. > > > > I also thought of mentioning the caveat of (un)scannability of function or > > filtered indexes but maybe that is a bit much. > > I have reviewed our documentation and found approrpiate places to > mention your floor() example, and my IS NULL example. Patch attached.
Patch applied back through 9.4. Thanks. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
