Re: [HACKERS] PostgreSQL 10 changes in exclusion constraints - didsomething change? CASE WHEN behavior oddity - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: [HACKERS] PostgreSQL 10 changes in exclusion constraints - didsomething change? CASE WHEN behavior oddity
Date
Msg-id 20170610180419.2gref4t7oipjcri5@alvherre.pgsql
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In response to Re: [HACKERS] PostgreSQL 10 changes in exclusion constraints - did something change? CASE WHEN behavior oddity  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [HACKERS] PostgreSQL 10 changes in exclusion constraints - did something change? CASE WHEN behavior oddity  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> I wrote:
> > Yes, we already have guards for those cases, but they return fairly opaque
> > error messages to the tune of "set-valued function called in context that
> > cannot accept a set", because the executor hasn't enough context to do
> > better.  I'd like the messages to be more specific, like "set-valued
> > function cannot appear within CASE" and so on.
> 
> Here's an expanded version of the "bottom up" patch that adjusts some
> parser APIs to allow these additional messages to be thrown.  This changes
> all occurrences of "set-valued function called in context that cannot
> accept a set" in the core regression tests into something more specific.
> There are probably some remaining cases that this doesn't cover, but the
> existing execution-time checks will still catch those.

Interesting stuff.  Here's a small recommendation for a couple of those
new messages.



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Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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