join condition against where with coalesce

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От Sim Zacks
Тема join condition against where with coalesce
Дата
Msg-id ej6m1n$1qep$1@news.hub.org
обсуждение исходный текст
Ответы Re: join condition against where with coalesce  (Sim Zacks <sim@compulab.co.il>)
Re: join condition against where with coalesce  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
Should there be any difference between:

select * from table1 a left join table2 b on a.pk=b.fk and b.typeid=14
and
select * from table1 a left join table2 b on a.pk=b.fk
where coalesce(b.typeid,14)=14

The reason I need to use the coalesce is because my goal is to do it with a full join and can't use
the and condition because it is not merge-joinable.

My test with the left join showed me that with the where it doesn't give any results, while I would
expect it to give me all the results in the first table.

Any thoughts?

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