On Sun, Apr 17, 2011 at 04:55:51PM +0100, Jack Douglas wrote: > I discovered the 'fields' option of 'interval', but i can't figure out > from the docs how it is supposed to work. Are "hour to minute" and "day > to minute" really the same thing? And if not, in what circumstances are > they treated differently? As of version 8.4, they behave identically. The code has this comment, some form of which probably belongs in the documentation: /* * Our interpretation of intervals with a limited set of fields is * that fields to the right of the last one specified are zeroed out, * but those to the left of it remain valid. Thus for example there * is no operational difference between INTERVAL YEAR TO MONTH and * INTERVAL MONTH. In some cases we could meaningfully enforce that * higher-order fields are zero; for example INTERVAL DAY could reject * nonzero "month" field. However that seems a bit pointless when we * can't do it consistently. (We cannot enforce a range limit on the * highest expected field, since we do not have any equivalent of * SQL's <interval leading field precision>.) * * Note: before PG 8.4 we interpreted a limited set of fields as * actually causing a "modulo" operation on a given value, potentially * losing high-order as well as low-order information. But there is * no support for such behavior in the standard, and it seems fairly * undesirable on data consistency grounds anyway. Now we only * perform truncation or rounding of low-order fields. */ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
