Re: [PATCHES] Inherited Constraints - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [PATCHES] Inherited Constraints
Date
Msg-id 200603030408.k2348j712285@candle.pha.pa.us
Whole thread Raw
In response to Re: [PATCHES] Inherited Constraints  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: [PATCHES] Inherited Constraints
List pgsql-hackers
Where are we on this patch?  My testing shows it is still shows we have
a problem:test=> CREATE TABLE x(y INT CHECK(y > 0));CREATE TABLEtest=> CREATE TABLE z(a INT) inherits (x);CREATE
TABLEtest=>ALTER TABLE z DROP CONSTRAINT "x_y_check";ALTER TABLEtest=> ALTER TABLE x DROP CONSTRAINT "x_y_check";ALTER
TABLE

Deleting the parent constraint first does not require CASCADE, as it
should, I think:test=> CREATE TABLE x(y INT CHECK(y > 0));CREATE TABLEtest=> CREATE TABLE z(a INT) inherits (x);CREATE
TABLEtest=>ALTER TABLE x DROP CONSTRAINT "x_y_check";ALTER TABLEtest=> ALTER TABLE z DROP CONSTRAINT "x_y_check";ERROR:
CONSTRAINT "x_y_check" does NOT exist
 

---------------------------------------------------------------------------

Simon Riggs wrote:
> On Thu, 2005-12-08 at 11:10 +0000, Simon Riggs wrote:
> > On Wed, 2005-12-07 at 21:24 +0000, Simon Riggs wrote:
> > > Following patch implements record of whether a constraint is inherited
> > > or not, and prevents dropping of inherited constraints.
> > 
> > Patch posted to -patches list.
> > 
> > > What it doesn't do:
> > > It doesn't yet prevent dropping the parent constraint, which is wrong,
> > > clearly, but what to do about it?
> > > 1. make dropping a constraint drop all constraints dependent upon it
> > > (without any explicit cascade)
> > > 2. add a new clause to ALTER TABLE .... DROP CONSTRAINT .... CASCADE 
> > > 
> > > I prefer (1), since it is SQL Standard compliant, easier to remember and
> > > automatic de-inheritance is the natural opposite of the automatic
> > > inheritance process.
> > 
> > Comments, please -hackers?
> 
> Late night hacking again....
> 
> ALTER TABLE .... DROP CONSTRAINT .... CASCADE
> 
> does of course already exist, so the following should cause dependency
> violation ERRORs:
> - omitting the CASCADE when attempting to delete parent constraint
> - attempting to drop the child constraint
> 
> Best Regards, Simon Riggs
> 
> 
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--  Bruce Momjian   http://candle.pha.pa.us SRA OSS, Inc.   http://www.sraoss.com
 + If your life is a hard drive, Christ can be your backup. +


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