| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | The Hermit Hacker <scrappy(at)hub(dot)org> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>, PostgreSQL Development <pgsql-hackers(at)postgreSQL(dot)org> |
| Subject: | Re: ALTER TABLE DROP COLUMN |
| Date: | 2000-10-09 17:32:56 |
| Message-ID: | 200010091732.NAA11347@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
> Basically, move the first 100 rows to the end of the table file, then take
> 100 and write it to position 0, 101 to position 1, etc ... that way, at
> max, you are using ( tuple * 100 ) bytes of disk space, vs 2x the table
> size ... either method is going to lock the file for a period of time, but
> one is much more friendly as far as disk space is concerned *plus*, if RAM
> is available for this, it might even be something that the backend could
> use up to -S blocks of RAM to do it off disk? If I set -S to 64meg, and
> the table is 24Meg in size, it could do it all in memory?
Yes, I liked that too.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
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