Re: COALESCE implementation question

At 17:22 5/08/00 +1000, Philip Warner wrote:
>P.S. What's worse, I should have mentioned that the plan *with* indexes
>seems flawed:
>
>Create Table t1(f1 int);
>Create Table t1(f1 int, f2 int);
>Create Unique Index t2f1 on t2(f1);
>Create Unique Index t2f2 on t2(f2);
>
>explain update t1 set f1 = Coalesce( (select f2 from t2 x where x.f1 =
>t1.f1), t1.f1);
>NOTICE:  QUERY PLAN:
>
>Seq Scan on t1  (cost=0.00..20.00 rows=1000 width=10)
>  SubPlan
>    ->  Index Scan using t2f1 on t2 x  (cost=0.00..8.14 rows=10 width=4)
>    ->  Seq Scan on t2 x  (cost=0.00..22.50 rows=1000 width=4)
>

Oddly enough, I now think that the EXPLAIN output is a lie; it seems that
it never does a sequential scan. So I am now even more confused...


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