Re: PostgreSQL vs SQL/XML Standards

From: Chapman Flack <chap(at)anastigmatix(dot)net>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Markus Winand <markus(dot)winand(at)winand(dot)at>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PostgreSQL vs SQL/XML Standards
Date: 2019-01-12 23:38:56
Message-ID: 5C3A7A90.3070207@anastigmatix.net
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On 12/30/18 03:23, Pavel Stehule wrote:
> Unfortunately, there is a different releases of libxml2 with different
> error reporting and it is hard (impossible) to prepare for all variants. :-/
>
> I prepare xml.out for my FC29 (fresh libxml2) and for no support xml.
> Other I prepare by patching - and this error (in context) is expected.

It turns out that the variant was already accounted for in the xml_2.out
variant result file, it just needed to have the new results added.

Done in xmltable-xpath-result-processing-bugfix-4.patch attached.

On 12/31/18 01:03, Pavel Stehule wrote:
> po 31. 12. 2018 v 3:15 odesílatel Chapman Flack <chap(at)anastigmatix(dot)net>
> napsal:
>> But the PostgreSQL situation is a little more strange. PG uses BY VALUE
>> semantics as the default when no passing method is specified. PG also uses
>> BY VALUE semantics when BY REF is explicitly requested, which is rude,
>> just like Oracle. But why should an explicit specification of BY VALUE
>> (which is, after all, the semantics we're going to use anyway!) produce
>> this?
>>
>> ERROR: syntax error at or near "value"
>>
>> To me, that doesn't seem like least astonishment.
>>
>> I am not seeing what would be complicated about removing that astonishment
>> by simply allowing the grammar productions to also consume BY VALUE and
>> ignore it.
>
> ok - I am not against implementation of ignored BY VALUE. But I don't like
> a idea to disable BY REF.

Done in attached xmltable-xmlexists-passing-mechanisms-1.patch along with
some corresponding documentation adjustments.

I am still working on more extensive documentation, but it seemed best
to include the changes related to BY REF / BY VALUE in the same patch
with the grammar change.

-Chap

Attachment Content-Type Size
xmltable-xpath-result-processing-bugfix-4.patch text/x-patch 13.4 KB
xmltable-xmlexists-passing-mechanisms-1.patch text/x-patch 5.8 KB

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