| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> |
| Cc: | "Peter Eisentraut" <peter_e(at)gmx(dot)net>, "PostgreSQL Development" <pgsql-hackers(at)postgreSQL(dot)org> |
| Subject: | Re: Happy column adding (was RE: [HACKERS] Happy column dropping) |
| Date: | 2000-01-25 17:23:15 |
| Message-ID: | 14033.948820995@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
"Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> writes:
>>>> Even default is not allowed in ADD COLUMN now.
>>
>> It's not a matter of *allowed*, it's a parsing deficiency. The fact that
>> there was a default declared gets silently ignored.
> IIRC,there were some reason that default for new column had been rejected.
Well, yeah: wouldn't you expect that "ADD COLUMN x DEFAULT 42" would
cause every row currently existing in the table to acquire x = 42,
rather than x = NULL? In fact that would *have* to happen to allow
constraints to be added; consider ADD COLUMN x DEFAULT 42 NOT NULL.
The only way to make that happen is for ADD COLUMN to switch over to
an implementation that rewrites all the tuples. Which I think is the
right way to go ... but per this discussion, it's not a trivial fix.
regards, tom lane
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