Re: pg_get_triggerdef in pg_dump - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: pg_get_triggerdef in pg_dump
Date
Msg-id 200306240252.h5O2q3011727@candle.pha.pa.us
Whole thread Raw
In response to Re: pg_get_triggerdef in pg_dump  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Add to TODO:
       o Allow ALTER TABLE to modify column lengths and change to binary         compatible types

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

Tom Lane wrote:
> "Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
> >> There might be other cases of legal direct change of system catalog 
> >> entries, e,g. varchar to text, if they all are only names for internally 
> >> identical data structures. Can you tell which datatypes may be legally 
> >> interchanged?
> 
> > Yes, you can check if they're binary compatible from the pg_cast table....
> 
> But nearly all of the interesting cases require you to understand the
> type's interpretation of typmod, and you can't learn that from a table.
> How many cases are there where blindly looking for a binary-compatible
> cast in pg_cast will really do you much good?  AFAICS you'd have to set
> atttypmod to -1 if you change atttypid without knowing very specifically
> what you are changing from and to.
> 
>             regards, tom lane
> 
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--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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