OMG, I never know what is index (Sorry for my newbies) I will study about them and update you all about their performance. Thanks and Regards Yan Cheng CHEOK --- On Wed, 1/13/10, Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx> wrote: > From: Craig Ringer <craig@xxxxxxxxxxxxxxxxxxxxx> > Subject: Re: Extremely Slow Cascade Delete Operation > To: "Yan Cheng Cheok" <yccheok@xxxxxxxxx> > Cc: pgsql-general@xxxxxxxxxxxxxx > Date: Wednesday, January 13, 2010, 7:01 PM > On 13/01/2010 4:09 PM, Yan Cheng > Cheok wrote: > > I have 3 tables - lot, unit and measurement > > > > 1 lot is having relationship to many unit. > > 1 unit is having relationship to many measurement. > > delete cascade is being used among their relationship > > > > > SemiconductorInspection=# delete from lot where lot_id > = 2; > > Are there indexes on fk_lot_id and fk_unit_id ? If not, a > DELETE from lot will cause a seqscan of unit for affected > units, and if any must be deleted each will cause a seqscan > of measurement for affected measurements. That's going to > get ugly fast. > > -- > Craig Ringer > > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
