Jon Nelson wrote:
> What is the difference between a plain join and a semi join?
As soon as a semi join finds a match it stops looking for more.
-Kevin
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On Mon, Mar 7, 2011 at 2:00 PM, Tom Lane wrote:
> Jon Nelson writes:
>> I was hoping that somebody could help me understand the differences
>> between three plans.
>> All of the plans are updating a table using a second table, and should
>> be logically equivalent.
>> Two of the plans use joins,
On Mon, Mar 7, 2011 at 1:07 PM, Jon Nelson wrote:
> Originally, I posted to -general but I found some time to write some
> samples, and realized it's probably more of a performance question.
>
> The original post is here:
> http://archives.postgresql.org/pgsql-general/2011-03/msg00198.php
>
> I wa
Jon Nelson writes:
> I was hoping that somebody could help me understand the differences
> between three plans.
> All of the plans are updating a table using a second table, and should
> be logically equivalent.
> Two of the plans use joins, and one uses an exists subquery.
> One of the plans uses
