-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 01/28/07 10:43, A. Kretschmer wrote: > am Sun, dem 28.01.2007, um 10:25:33 -0600 mailte Ron Johnson folgendes: >> Hi. >> >> These fields do not use any disk space, as the data in them is >> derived on the fly. >> >> For example: >> CREATE TABLE T_EXAMPLE ( >> SOME_DATE DATE, >> JDATE COMPUTED BY EXTRACT(JULIAN FROM SOME_DATE) >> ); >> >> A work-around is to create a function, and reference it in every >> query, but storing them in the table definition is the "tidy", >> low-maintenance way to do it. > > Was this a question how to do this in PostgreSQL? > > You can use a VIEW. Just create T_EXAMPLE ( SOME_DATE DATE ); > and then > > CREATE VIEW view_example AS SELECT some_date, EXTRACT(JULIAN FROM > some_date) AS julian_date FROM T_EXAMPLE;
Good point. But then you have 2 bits of metadata, and yet one more object to update when you add a column. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFFvNQjS9HxQb37XmcRArguAJ4y4e5rbpe4YoH+VNJXIW0XSrjRqQCfcLO4 78WYNnFb14wlI9hXJtwbSeM= =KZkP -----END PGP SIGNATURE----- ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
