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Re: Optimising a query - Mailing list pgsql-performance

From Jeremy Harris
Subject Re: Optimising a query
Date
Msg-id 476950E8.50009@wizmail.org
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In response to Optimising a query  (Paul Lambert <paul.lambert@reynolds.com.au>)
List pgsql-performance
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Paul Lambert wrote:
> "                                            ->  Merge Join
> (cost=35.56..19732.91 rows=12 width=48) (actual time=0.841..2309.828
> rows=206748 loops=1)"

I'm no expert, but in the interests of learning: why is the
rows estimate so far out for this join?

Thanks,
    Jeremy

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