| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | cpainterwakefield(at)gmail(dot)com |
| Cc: | pgsql-docs(at)lists(dot)postgresql(dot)org |
| Subject: | Re: clarification on chaining of set operations |
| Date: | 2021-10-04 23:40:38 |
| Message-ID: | 4017319.1633390838@sss.pgh.pa.us |
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| Lists: | pgsql-docs |
PG Doc comments form <noreply(at)postgresql(dot)org> writes:
> Regarding section 7.4 of the documentation. I was curious about the
> behavior when combining different set operations in one query, e.g,
> query1 op1 query2 op2 query3;
> where op1 and op2 are one of UNION, INTERSECT, EXCEPT.
> The documentation suggests that this is equivalent to
> (query1 op1 query2) op2 query3;
> but only states it for the case when op1 = op2 = UNION.
The SELECT reference page explains that INTERSECT binds more tightly
than UNION or EXCEPT. I think it's an oversight that section 7.4
doesn't mention that.
regards, tom lane
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