Re: Doubt in index subplan query

On Jun 20, 2008, at 1:11 AM, Suresh wrote:
> I have a query plan for a certain query
>
> Nested Loop (cost=100000000.00..38761761090.50 rows=3000608 width=8)
> -> Seq Scan on lineitem (cost=100000000.00..100213649.15
> rows=6001215 width=8)
> -> Index Scan using oindex2 on myorders (cost=0.00..6442.27
> rows=1 width=4)
> Index Cond: ("outer".l_orderkey = myorders.o_orderkey)
> Filter: (subplan)
> SubPlan
> -> Index Scan using cnation on customer
> (cost=0.00..12859.39 rows=5251 width=0)
> Index Cond: (c_nationkey = 10)
>
> How is the subplan handled by postgres at index level ? Is any sort
> of hashing done ?

This is better asked on pgsql-general... but the subplan does exactly
what it says; an index scan. It will be executed for every row of the
calling query.
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