Re: BUG #17877: Referencing a system column in a foreign key leads to incorrect memory access
| От | Ranier Vilela |
|---|---|
| Тема | Re: BUG #17877: Referencing a system column in a foreign key leads to incorrect memory access |
| Дата | |
| Msg-id | CAEudQAq=q1xGR+Ju4L=ss+dv2-+PsPSqQbLuGUBKrOpKfxOz9g@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: BUG #17877: Referencing a system column in a foreign key leads to incorrect memory access (Tom Lane <tgl@sss.pgh.pa.us>) |
| Ответы |
Re: BUG #17877: Referencing a system column in a foreign key leads to incorrect memory access
|
| Список | pgsql-hackers |
Em sex., 31 de mar. de 2023 às 16:25, Tom Lane <tgl@sss.pgh.pa.us> escreveu:
Ranier Vilela <ranier.vf@gmail.com> writes:
> I think that commit f0d65c0
> <https://github.com/postgres/postgres/commit/f0d65c0eaf05d6acd3ae05cde4a31465eb3992b2>
> has an oversight.
> Attnum == 0, is system column too, right?
No, it's not valid in pg_attribute rows.
> All other places at tablecmds.c, has this test:
> if (attnum <= 0)
> ereport(ERROR,
I was actually copying this code in indexcmds.c:
if (attno < 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("index creation on system columns is not supported")));
There's really no reason to prefer one over the other in this context.
I think the documentation is a bit confusing.
According to the current documentation:
/*
* attnum is the "attribute number" for the attribute: A value that
* uniquely identifies this attribute within its class. for user
* attributes, Attribute numbers are greater than 0 and not greater than
* the number of attributes in the class. i.e. if the Class pg_class says
* that Class XYZ has 10 attributes, then the user attribute numbers in
* Class pg_attribute must be 1-10.
*
* System attributes have attribute numbers less than 0 that are unique
* within the class, but not constrained to any particular range.
*
* Note that (attnum - 1) is often used as the index to an array.
Attributes equal to zero are in limbo.
According to the current documentation:
/*
* attnum is the "attribute number" for the attribute: A value that
* uniquely identifies this attribute within its class. for user
* attributes, Attribute numbers are greater than 0 and not greater than
* the number of attributes in the class. i.e. if the Class pg_class says
* that Class XYZ has 10 attributes, then the user attribute numbers in
* Class pg_attribute must be 1-10.
*
* System attributes have attribute numbers less than 0 that are unique
* within the class, but not constrained to any particular range.
*
* Note that (attnum - 1) is often used as the index to an array.
Attributes equal to zero are in limbo.
IMO should be:
* System attributes have attribute numbers less or equal to 0 that are
* unique
* within the class, but not constrained to any particular range.
* System attributes have attribute numbers less or equal to 0 that are
* unique
* within the class, but not constrained to any particular range.
regards,
Ranier Vilela
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