Re: [HACKERS] [GENERAL] Remove useless joins (VARCHAR vs TEXT)

David Rowley <david.rowley@2ndquadrant.com> writes:
> On 17 September 2017 at 08:07, Kim Rose Carlsen <krc@hiper.dk> wrote:
>> It seems there are some difference in VARCHAR vs TEXT when postgres tries to
>> decide if a LEFT JOIN is useful or not.

> Yeah, it looks like the code to check for distinctness in the subquery
> fails to consider that the join condition may contain RelabelTypes
> instead of plain Vars.
>
> The attached fixes.

Looks like a good fix to me (except for the copied-and-pasted,
not-quite-on-point comment ;-)).  Pushed.
        regards, tom lane


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