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От | root@blik.samara.su (Samara CIT) |
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Тема | ... |
Дата | |
Msg-id | 199812291025.OAA19563@blik.samara.su обсуждение исходный текст |
Список | pgsql-hackers |
>From [194.58.47.100]!mcit.aris.ru!hub.org!owner-pgsql-hackers Mon Dec 28 10:36:52 GMT 1998 remote from doom Received: from mcit.aris.ru ([194.58.47.100]) by doom.samara.su with SMTP id AA00394 (5.65/IDA-simtel for <evg@relay1.cit.ru>);Mon, 28 Dec 1998 10:36:52 +0400 Received: from hub.org by mcit.aris.ru with ESMTP id JAA15478; (8.8.5-MVC-230497/vak/1.9) Sun, 27 Dec 1998 09:45:26 +0300(MSK) Received: from localhost (majordom@localhost)by hub.org (8.9.1/8.9.1) with SMTP id BAA04767;Sun, 27 Dec 1998 01:40:47 -0500(EST)(envelope-from owner-pgsql-hackers@hub.org) Received: by hub.org (TLB v0.10a (1.23 tibbs 1997/01/09 00:29:32)); Sun, 27 Dec 1998 01:36:02 +0000 (EST) Received: (from majordom@localhost)by hub.org (8.9.1/8.9.1) id BAA03806for pgsql-hackers-outgoing; Sun, 27 Dec 1998 01:35:28-0500 (EST)(envelope-from owner-pgsql-hackers@postgreSQL.org) Received: from trends.net (root@clio.trends.ca [209.47.148.2])by hub.org (8.9.1/8.9.1) with ESMTP id BAA03232for <pgsql-hackers@postgresql.org>;Sun, 27 Dec 1998 01:30:30 -0500 (EST)(envelope-from honza@ied.com) Received: from enrico.ied.com (root@miranda.uwaterloo.ca [129.97.130.69])by trends.net (8.8.8/8.8.8) with ESMTP id WAA26868for<pgsql-hackers@postgreSQL.org>; Sat, 26 Dec 1998 22:37:23 -0500 (EST) Received: from ann.ied.com (honza@ann.ied.com [192.168.200.20])by enrico.ied.com (8.8.7/8.8.7) with ESMTP id WAA25889for<pgsql-hackers@postgreSQL.org>; Sat, 26 Dec 1998 22:36:23 -0500 Date: Sat, 26 Dec 1998 22:36:53 -0500 (EST) From: Jan Vicherek <honza@ied.com> To: pgsql-hackers@postgreSQL.org Subject: [HACKERS] space usage of NULL fields Message-Id: <Pine.LNX.4.04.9812262213380.11035-100000@ann.ied.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-pgsql-hackers@postgreSQL.org Precedence: bulk Hello, a quick question (I couldn't contact postgresql.org, so I didn't check the FAQ, but I doubt it would be there.) When I create a table with field "nnn float8" and total row size, say 140 bytes, and then I insert a row with NULL in this field, will my record take up those 8 bytes in physical page (say 140 bytes) or will it take up less (like 140-8=132), i.e. will it be shortened by those 8 bytes, since the value is NULL and no information is stored in that field ? ( I *hate* run-on sentences :) In general, what are the savings/overheads associated in PG with NULL/not NULL fields ? I.e. if will I save the space if I define the field as varchar(8) instead of float8 ? Thanx, Jan -- Gospel of Jesus is the saving power of God for all who believe -- ## To some, nothing is impossible. ## http://Vicherek.Waterloo.on.ca/
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