Обсуждение: defferable update & unique
Hi All Does 7.4 support defferable updates on unique column ? example unique INT colum named u_test has the following values: 1, 2, 3, 4, 5 can i do update table set u_test = u_test + 1; cheers -------------------------- Canaan Surfing Ltd. Internet Service Providers Ben-Nes Michael - Manager Tel: 972-4-6991122 Fax: 972-4-6990098 http://www.canaan.net.il --------------------------
On Wed, 19 Nov 2003, Ben-Nes Michael wrote: > Does 7.4 support defferable updates on unique column ? Not yet, and I'm not sure if any work is actively being done on it (although some discussions on ways to handle it have happened fairly recently)
Ben-Nes Michael wrote: > Hi All > > Does 7.4 support defferable updates on unique column ? > > example > > unique INT colum named u_test has the following values: 1, 2, 3, 4, 5 > > can i do update table set u_test = u_test + 1; No, this is on our TODO list. Also, I can't think of a workaround. :-( -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
On Wed, 19 Nov 2003, Bruce Momjian wrote: > Ben-Nes Michael wrote: > > Hi All > > > > Does 7.4 support defferable updates on unique column ? > > > > example > > > > unique INT colum named u_test has the following values: 1, 2, 3, 4, 5 > > > > can i do update table set u_test = u_test + 1; > > No, this is on our TODO list. Also, I can't think of a workaround. :-( If negative values aren't allowed normally, I think you can do it in an ugly fashion through two updates, something like: update table set u_test=-u_test-1; update table set u_test=-u_test;
"Ben-Nes Michael" <miki@canaan.co.il> writes: > Does 7.4 support defferable updates on unique column ? no -- greg
Stephan Szabo wrote: > On Wed, 19 Nov 2003, Bruce Momjian wrote: > > > Ben-Nes Michael wrote: > > > Hi All > > > > > > Does 7.4 support defferable updates on unique column ? > > > > > > example > > > > > > unique INT colum named u_test has the following values: 1, 2, 3, 4, 5 > > > > > > can i do update table set u_test = u_test + 1; > > > > No, this is on our TODO list. Also, I can't think of a workaround. :-( > > If negative values aren't allowed normally, I think you can do it in an > ugly fashion through two updates, something like: > > update table set u_test=-u_test-1; > update table set u_test=-u_test; Excellent idea. You might want to add a VACUUM in there: > update table set u_test=-u_test-1; > VACUUM > update table set u_test=-u_test; > VACUUM -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073
i found a workaround, but relativly slow. The column is not unique and when the update is finished i fire up a trigger that check for uniqueness. lets wait for pg7.5 :) -------------------------- Canaan Surfing Ltd. Internet Service Providers Ben-Nes Michael - Manager Tel: 972-4-6991122 Fax: 972-4-6990098 http://www.canaan.net.il -------------------------- ----- Original Message ----- From: "Bruce Momjian" <pgman@candle.pha.pa.us> To: "Ben-Nes Michael" <miki@canaan.co.il> Cc: "postgresql" <pgsql-general@postgresql.org> Sent: Wednesday, November 19, 2003 6:39 PM Subject: Re: [GENERAL] defferable update & unique > Ben-Nes Michael wrote: > > Hi All > > > > Does 7.4 support defferable updates on unique column ? > > > > example > > > > unique INT colum named u_test has the following values: 1, 2, 3, 4, 5 > > > > can i do update table set u_test = u_test + 1; > > No, this is on our TODO list. Also, I can't think of a workaround. :-( > > -- > Bruce Momjian | http://candle.pha.pa.us > pgman@candle.pha.pa.us | (610) 359-1001 > + If your life is a hard drive, | 13 Roberts Road > + Christ can be your backup. | Newtown Square, Pennsylvania 19073 >