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Re: _bt_check_unique checks every row in table when doing update?? - Mailing list pgsql-bugs

From Tom Lane
Subject Re: _bt_check_unique checks every row in table when doing update??
Date
Msg-id 13421.1031602910@sss.pgh.pa.us
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In response to _bt_check_unique checks every row in table when doing update??  (Mats Lofkvist <mal@algonet.se>)
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Mats Lofkvist <mal@algonet.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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