From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
Cc: | Rob Sargent <robjsargent(at)gmail(dot)com>, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>, "pgsql-generallists(dot)postgresql(dot)org" <pgsql-general(at)lists(dot)postgresql(dot)org> |
Subject: | Re: schema agnostic functions in language sql |
Date: | 2020-05-15 23:41:24 |
Message-ID: | 17840.1589586084@sss.pgh.pa.us |
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Lists: | pgsql-general |
"David G. Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> writes:
> Yes, SQL and pl/pgsql have very different behaviors when it comes to
> compilation and execution. In particular SQL performs parsing earlier
> (during creation - just like it does for views) and links the textual query
> to its parse result earlier. For pl/pgsql none of that happens until the
> function is called. Because of this pl/pgsql allows for ambiguous sql text
> to exist and be concretely resolved during execution while SQL does not.
I don't think that's accurate. SQL functions are stored as plain text,
just like any other non-C-coded function, and they are not parsed until
execution.
There are big differences from plpgsql of course. For one, it's
possible for a SQL function to be "inlined" into the calling query,
in which case parsing happens during planning of the calling query.
But other than that, I'd expect the execution-time search path
to determine how a SQL function behaves.
Since Rob didn't provide any details, it's far from clear what's
going wrong for him.
regards, tom lane
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