RE: [HACKERS] Duplicate constraint names in 7.0.3
OK, I have modifed heap.c so that it won't automatically generate duplicate constraint names. I have _not_ compiled this yet, as it's a bit of a pain for me cos I don't have bison, etc. However, it looks good to me, and if someone else wants to test it and then maybe think about if the patch is necessary that's fine by me. If no-one wants to test it, I will eventually get around to testing it myself. Given that this is my first code patch for Postgres - I should treat it with caution! Chris -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Christopher Kings-Lynne Sent: Friday, 4 May 2001 12:33 PM To: Hackers Subject: RE: [HACKERS] Duplicate constraint names in 7.0.3 A reasonable interpretation of DROP CONSTRAINT foo is to drop *all* constraints named foo on the target table. Then it should probably be a good thing to avoid the automatic generation of duplicate names? I might take a look at that, actually... Chris ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl heap.diff ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: [HACKERS] Duplicate constraint names in 7.0.3
If I read the spec correctly, table constraint names are supposed to be unique across a schema. So technically the constraint name should also not conflict with the name of an fk constraint, or a unique index. In addition, generated constraint names are supposed to follow the same syntax rules (which includes the uniqueness) which seems to imply that in cases like the below, that's not an error, and a different name should be generated for the unnamed constraint. However, unnamed column constraints seem to get the empty string as a name. I'd say don't worry about it for the purposes of drop constraint. :) On Fri, 4 May 2001, Christopher Kings-Lynne wrote: Hi, I have noticed that it is possible to create duplicate CHECK (haven't tried other) constraints in 7.0.3 by doing something like this: CREATE TABLE test ( a int4, CHECK (a 400), CONSTRAINT $1 CHECK (a 5) ); I was just fiddling around with trying to implement the 'DROP CONSTRAINT' code (it's quite hard - don't wait up for me!) and it would seem to be a bad thing that it's possible to have two constraints with the same name in a table. Surely there should be a UNIQUE (rcrelid, rcname) on pg_relcheck?, or at least better checking in the CREATE TABLE code? ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
RE: [HACKERS] Duplicate constraint names in 7.0.3
I left it unsaid that, in fact, all constraint names should be unique. Unnamed column constraints as far as I can tell get a '$n' automatically assigned name. Maybe the create table function should process named constraints first, and then the unnamed ones to prevent such a problem? Chris -Original Message- From: Stephan Szabo [mailto:[EMAIL PROTECTED]] Sent: Friday, 4 May 2001 10:48 AM To: Christopher Kings-Lynne Cc: Hackers Subject: Re: [HACKERS] Duplicate constraint names in 7.0.3 If I read the spec correctly, table constraint names are supposed to be unique across a schema. So technically the constraint name should also not conflict with the name of an fk constraint, or a unique index. In addition, generated constraint names are supposed to follow the same syntax rules (which includes the uniqueness) which seems to imply that in cases like the below, that's not an error, and a different name should be generated for the unnamed constraint. However, unnamed column constraints seem to get the empty string as a name. I'd say don't worry about it for the purposes of drop constraint. :) On Fri, 4 May 2001, Christopher Kings-Lynne wrote: Hi, I have noticed that it is possible to create duplicate CHECK (haven't tried other) constraints in 7.0.3 by doing something like this: CREATE TABLE test ( a int4, CHECK (a 400), CONSTRAINT $1 CHECK (a 5) ); I was just fiddling around with trying to implement the 'DROP CONSTRAINT' code (it's quite hard - don't wait up for me!) and it would seem to be a bad thing that it's possible to have two constraints with the same name in a table. Surely there should be a UNIQUE (rcrelid, rcname) on pg_relcheck?, or at least better checking in the CREATE TABLE code? ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] Duplicate constraint names in 7.0.3
Stephan Szabo [EMAIL PROTECTED] writes: If I read the spec correctly, table constraint names are supposed to be unique across a schema. That's what the spec says, but I doubt we should enforce it. For one thing, what do you do with inherited constraints? Invent a random name for them? No thanks. The absolute limit of what I'd accept is constraint name unique for a given table ... and even that seems like an unnecessary restriction. I was just fiddling around with trying to implement the 'DROP CONSTRAINT' code (it's quite hard - don't wait up for me!) and it would seem to be a bad thing that it's possible to have two constraints with the same name in a table. A reasonable interpretation of DROP CONSTRAINT foo is to drop *all* constraints named foo on the target table. regards, tom lane ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl
Re: [HACKERS] Duplicate constraint names in 7.0.3
On Thu, 3 May 2001, Tom Lane wrote: Stephan Szabo [EMAIL PROTECTED] writes: If I read the spec correctly, table constraint names are supposed to be unique across a schema. That's what the spec says, but I doubt we should enforce it. For one thing, what do you do with inherited constraints? Invent a random name for them? No thanks. The absolute limit of what I'd accept is constraint name unique for a given table ... and even that seems like an unnecessary restriction. The only thing I'd say is it might be confusing to people that some constraint names must be unique (unique, primary key) and that others can be duplicated (check, foreign key), not that all that many people probably name their unique constraints. I was just fiddling around with trying to implement the 'DROP CONSTRAINT' code (it's quite hard - don't wait up for me!) and it would seem to be a bad thing that it's possible to have two constraints with the same name in a table. A reasonable interpretation of DROP CONSTRAINT foo is to drop *all* constraints named foo on the target table. Definately true if non-unique names are allowed. ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
RE: [HACKERS] Duplicate constraint names in 7.0.3
A reasonable interpretation of DROP CONSTRAINT foo is to drop *all* constraints named foo on the target table. Then it should probably be a good thing to avoid the automatic generation of duplicate names? I might take a look at that, actually... Chris ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://www.postgresql.org/search.mpl
