Re: Table/Column Constraints

At 00:22 21/11/00 -0500, Rod Taylor wrote:
>Christopher Kings-Lynne wrote:
>
>/*******************************
> * TABLE: example
> *
> * Used to accomplish stuff
> */
>CREATE TABLE example
> ( example_id serial
>
> /* Must be a ZIP or Postal Code */
> , region varchar(6) UNIQUE
> NOT NULL
>
> /* Descriptive text */
> , description varchar(60) NOT NULL
> );

From the point of view of efficient dump & load, I think you actually need
to dump:

CREATE TABLE example
( example_id serial

-- Must be a ZIP or Postal Code
, region varchar(6)

-- Descriptive text
, description varchar(60)
);

Followed by:

ALTER TABLE example Alter Column region UNIQUE NOT NULL;
...etc. (Whatever the correct syntax is).

The reason for this is that UNIQUE constraints in particular are probably
very nasty things to check when loading a table. I would expect it to be
more efficient to create tables, load them, and define constraints. Also,
for FK constraints this is essential. Unless of course someone implements a
'SET ALL CONSTRAINTS OFF/ON'.

It is also nice to be able to dump constraints only.

So it's definitely a good idea to separate them, IMO.

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