| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Mats Lofkvist <mal(at)algonet(dot)se>, pgsql-bugs(at)postgresql(dot)org |
| Subject: | Re: _bt_check_unique checks every row in table when doing update?? |
| Date: | 2002-09-12 16:26:47 |
| Message-ID: | 200209121626.g8CGQl804506@candle.pha.pa.us |
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| Lists: | pgsql-bugs |
Tom Lane wrote:
> > (In my case, I think the call to _bt_check_unique could be
> > avoided altogether since the update isn't changing any of
> > the columns present in the unique key.
>
> It's fairly difficult for the index AM to know that; in general we don't
> have access to the old tuple to check, at the time the index update is
> running.
We do have a TODO item:
* Prevent index uniqueness checks when UPDATE does not modifying column
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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