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From: Tom Lane <tgl@sss.pgh.pa.us>
To: John Lumby <johnlumby@hotmail.com>
cc: "David G. Johnston" <david.g.johnston@gmail.com>,
        pgsql-sql <pgsql-sql@lists.postgresql.org>
Subject: Re: value returned by EXTRACT, date_part
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Comments: In-reply-to John Lumby <johnlumby@hotmail.com>
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John Lumby <johnlumby@hotmail.com> <DM6PR06MB55625C1A9319BC921F4FB4ACA3530=
@DM6PR06MB5562.namprd06.prod.outlook.com> writes:
> What is not clear to me is how the "components" (aka "subfields") of an =

> interval are defined.

The spec says that year,month,day,hour,minute,second are independent
fields.  Postgres doesn't implement it quite that way: we treat the
basic fields as being months, days, and (micro)seconds, folding the
other values into those for storage.  That's why "14 months" comes out
as "1 year 2 months", for example.

			regards, tom lane