From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
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To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
Cc: | PostgreSQL Development <pgsql-hackers(at)postgreSQL(dot)org> |
Subject: | Re: [HACKERS] Re: ALTER TABLE DROP COLUMN |
Date: | 2000-02-28 00:17:08 |
Message-ID: | 200002280017.TAA11268@candle.pha.pa.us |
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Lists: | pgsql-hackers |
[Charset ISO-8859-1 unsupported, filtering to ASCII...]
> Bruce Momjian writes:
>
> > You can exclusively lock the table, then do a heap_getnext() scan over
> > the entire table, remove the dropped column, do a heap_insert(), then a
> > heap_delete() on the current tuple,
>
> Wow, that almost seems to easy to be true. I never thought that having
> tuples of different structures in the table at the same time would be
> possible. If so then I don't see a reason why this would be too hard to
> do.
If the transaction is not committed, I don't think anything actually
reads the tuple columns, so you are safe.
--
Bruce Momjian | http://www.op.net/~candle
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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