pgsql-server/src/bin/psql print.c

Out of interest, how does one get a table of no columns?

Chris

On Fri, 1 Nov 2002, Tom Lane wrote:

On Sun, 2002-11-03 at 06:37, Christopher Kings-Lynne wrote:

Out of interest, how does one get a table of no columns?

ALTER TABLE DROP COLUMN :)

On Fri, 1 Nov 2002, Tom Lane wrote:

CVSROOT: /cvsroot
Module name: pgsql-server
Changes by: tgl@postgresql.org 02/11/01 10:12:19

Modified files:
src/bin/psql : print.c

Log message:
Avoid malloc(0) when printing a table of no columns. On some platforms
this returns NULL, which confuses the code.

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Rod Taylor

Nup - DROP COLUMN (well at least the code I wrote) deliberately prevents you
from doing that!

Chris

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:

Nup - DROP COLUMN (well at least the code I wrote) deliberately prevents you
from doing that!

Yeah, but we ripped it out later, per this CVS log entry:

2002-09-28 16:00 tgl

* src/: backend/access/common/tupdesc.c,
backend/commands/tablecmds.c, backend/executor/execTuples.c,
backend/executor/nodeAgg.c, backend/parser/parse_target.c,
test/regress/expected/alter_table.out (REL7_3_STABLE),
backend/access/common/tupdesc.c, backend/commands/tablecmds.c,
backend/executor/execTuples.c, backend/executor/nodeAgg.c,
backend/parser/parse_target.c,
test/regress/expected/alter_table.out: Make the world at least
somewhat safe for zero-column tables, and remove the special case
in ALTER DROP COLUMN to prohibit dropping a table's last column.

I forget the details of the discussion leading up to that, but we
decided that prohibiting a DROP of a table's last column was creating
so much ugliness that we should try to remove the restriction; and upon
looking into it, there weren't *that* many places that would choke on
it. So as of the last month or so, you can do it. I would not be
surprised to find one or two more lurking problems with zero-column
tables, but I'd rather fix those than have the weird special case.

regards, tom lane

Ah ok - so it's something that went in while I wasn't subscribed. Do you
now allow this as well?

CREATE TABLE test ();

Chris

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:

Ah ok - so it's something that went in while I wasn't subscribed. Do you
now allow this as well?

CREATE TABLE test ();

No. In theory we could, but I'm not seeing the point; do you have an
example where this would be useful?

regards, tom lane

"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:

Ah ok - so it's something that went in while I wasn't

subscribed. Do you

now allow this as well?

CREATE TABLE test ();

No. In theory we could, but I'm not seeing the point; do you have an
example where this would be useful?

Not in the slightest - it'd just be consistent ;)

I don't advocate implementing it either!

Chris