Re: _bt_check_unique checks every row in table when doing update??

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Mats Lofkvist <mal(at)algonet(dot)se>
Cc: pgsql-bugs(at)postgresql(dot)org
Subject: Re: _bt_check_unique checks every row in table when doing update??
Date: 2002-09-09 20:21:50
Message-ID: 13421.1031602910@sss.pgh.pa.us
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Mats Lofkvist <mal(at)algonet(dot)se> writes:
> But when doing ~1000 updates (i.e. setting val0 and val1 with
> a where on an existing key0/key1/key2 triplet), I get this which
> seems very strange to me:

I suppose you repeatedly updated the same row 1000 times? That creates
an O(N^2) behavior because the dead tuples have to be rechecked again
and again.

7.3 will be smarter about this.

regards, tom lane

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