| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | pgsql-committers(at)lists(dot)postgresql(dot)org |
| Subject: | pgsql: Doc: add example of type resolution in nested UNIONs. |
| Date: | 2018-03-25 20:15:34 |
| Message-ID: | E1f0C3C-0002eg-36@gemulon.postgresql.org |
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| Lists: | pgsql-committers |
Doc: add example of type resolution in nested UNIONs.
Section 10.5 didn't say explicitly that multiple UNIONs are resolved
pairwise. Since the resolution algorithm is described as taking any
number of inputs, readers might well think that a query like
"select x union select y union select z" would be resolved by
considering x, y, and z in one resolution step. But that's not what
happens (and I think that behavior is per SQL spec). Add an example
clarifying this point.
Per bug #15129 from Philippe Beaudoin.
Discussion: https://postgr.es/m/152196085023.32649.9916472370480121694@wrigleys.postgresql.org
Branch
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REL_10_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/915bed756da0a91cad589dd9c213b924ace5a17a
Modified Files
--------------
doc/src/sgml/typeconv.sgml | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
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