Re: BETWEEN Node & DROP COLUMN - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: BETWEEN Node & DROP COLUMN
Date
Msg-id 200207040038.g640c4F28847@candle.pha.pa.us
Whole thread Raw
In response to BETWEEN Node & DROP COLUMN  ("Christopher Kings-Lynne" <chriskl@familyhealth.com.au>)
List pgsql-hackers
Hiroshi Inoue wrote:
> Bruce Momjian wrote:
> > 
> > Hiroshi Inoue wrote:
> > > > As I remember, Hiroshi's drop column changed the attribute number to a
> > > > special negative value, which required lots of changes to track.
> > >
> > > ??? What do you mean by *lots of* ?
> > 
> > Yes, please remind me.  Was your solution renumbering the attno values?
> 
> Yes though I don't intend to object to Christopher's proposal.
> 
> > I think there are fewer cases to fix if we keep the existing attribute
> > numbering and just mark the column as deleted.  Is this accurate?
> 
> No. I don't understand why you think so. 

With the isdropped column, you really only need to deal with '*'
expansion in a few places, and prevent the column from being accessed. 
With renumbering, the backend loops that go through the attnos have to
be dealt with.

Is this correct?  I certainly prefer attno renumbering to isdropped
because it allows us to get DROP COLUMN without any client changes, or
at least with fewer because the dropped column has a negative attno.  Is
this accurate?

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
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