Thread: thw rewriter and default values, again
Hi, here we go again... As you know there is a problem executing something like: create table foo ( col1 serial, col2 int ); create view v_foo as select * from foo; create rule ins_rule as on insert to v_foo do instead insert into foo(col1, col2) values (new.col1, new.col2); insert into v_foo(col2) values (1); this give an error like: psql:f:/views.sql:13: ERROR: null value in column "col1" violates not-null constraint ---- There is a workaround about this creating default values to the view. Now, for updateable views we need this happen automatically, attached there is a solution to this. The only problem i have found until now is that update v_foo set col1 = DEFAULT; execute nextval twice per every record. so there will be a gasp between numbers, but AFAIK nextval has no guarantee of returning sequential numbers. Any comments on this? -- regards, Jaime Casanova (DBA: DataBase Aniquilator ;)
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Jaime Casanova <systemguards@gmail.com> writes: > The only problem i have found until now is that > update v_foo set col1 = DEFAULT; execute nextval twice per every record. > so there will be a gasp between numbers, but AFAIK nextval has no guarantee > of returning sequential numbers. While there's no guarantee that strong there's still an expected behaviour. sequences generate sequential numbers and only skip in specific cases. I think this would still surprise and bother most users. -- greg
Jaime Casanova <systemguards@gmail.com> writes: > create rule ins_rule as on insert to v_foo do instead > insert into foo(col1, col2) values (new.col1, new.col2); > insert into v_foo(col2) values (1); > this give an error like: > psql:f:/views.sql:13: ERROR: null value in column "col1" violates > not-null constraint That's not a bug, and "fixing" it isn't acceptable. The correct solution to the problem you are looking at is to attach default expressions to the view itself. Adding alter table v_foo alter col1 set default nextval('public.foo_col1_seq'); to your example makes it work as you wish. regards, tom lane
On 5/28/05, Tom Lane <tgl@sss.pgh.pa.us> wrote: > Jaime Casanova <systemguards@gmail.com> writes: > > create rule ins_rule as on insert to v_foo do instead > > insert into foo(col1, col2) values (new.col1, new.col2); > > > insert into v_foo(col2) values (1); > > > this give an error like: > > psql:f:/views.sql:13: ERROR: null value in column "col1" violates > > not-null constraint > > That's not a bug, and "fixing" it isn't acceptable. > > The correct solution to the problem you are looking at is > to attach default expressions to the view itself. Adding > > alter table v_foo alter col1 set default nextval('public.foo_col1_seq'); > > to your example makes it work as you wish. > I know you're right, but -when dealing with updateable views- doing that implies to add a lot of time altering views when base table change, and of course we maybe don't want all views get that values. -- regards, Jaime Casanova (DBA: DataBase Aniquilator ;)
On 28 May 2005 10:25:48 -0400, Greg Stark <gsstark@mit.edu> wrote: > > Jaime Casanova <systemguards@gmail.com> writes: > > > The only problem i have found until now is that > > update v_foo set col1 = DEFAULT; execute nextval twice per every record. > > so there will be a gasp between numbers, but AFAIK nextval has no > guarantee > > of returning sequential numbers. > > While there's no guarantee that strong there's still an expected behaviour. > sequences generate sequential numbers and only skip in specific cases. > > I think this would still surprise and bother most users. > Certainly, i will look deeper in it. -- regards, Jaime Casanova (DBA: DataBase Aniquilator ;)
Jaime Casanova wrote: > I know you're right, but -when dealing with updateable views- doing > that implies to add a lot of time altering views when base table > change, and of course we maybe don't want all views get that values. Sorry for the late posting on this thread. Might there be any way to have something like ...SET DEFAULT pg_same_as('public','foo','col1'). Hmm - you'd need pg_same_as_int/text/etc. depending on the return-type - still not ideal. -- Richard Huxton Archonet Ltd
On 6/6/05, Richard Huxton <dev@archonet.com> wrote: > Jaime Casanova wrote: > > I know you're right, but -when dealing with updateable views- doing > > that implies to add a lot of time altering views when base table > > change, and of course we maybe don't want all views get that values. > > Sorry for the late posting on this thread. > > Might there be any way to have something like ...SET DEFAULT > pg_same_as('public','foo','col1'). > > Hmm - you'd need pg_same_as_int/text/etc. depending on the return-type - > still not ideal. > Actually, i try to do that but i need the function to be polymorphic and because polymorphic functions needs to receive at least one polymorphic argument that teach about the return type of the function i can't go ahead with this idea. About the code i talk earler in this thread i solve the problem with the update to serial columns. -- Atentamente, Jaime Casanova (DBA: DataBase Aniquilator ;)