Re: [HACKERS] patch: function xmltable

Given
https://www.postgresql.org/message-id/20170116210019.a3glfwspg5lnfrnm@alap3.anarazel.de
which is going to heavily change how the executor works in this area, I
am returning this patch to you again.  I would like a few rather minor
changes:

1. to_xmlstr can be replaced with calls to xmlCharStrdup.
2. don't need xml_xmlnodetostr either -- just use xml_xmlnodetoxmltype  (which returns text*) and extract the cstring
fromthe varlena.  It's  a bit more wasteful in terms of cycles, but I don't think we care.  If we do care, change the
functionso that it returns cstring, and  have the callers that want text wrap it in cstring_to_text.
 
3. have a new perValueCxt memcxt in TableExprState, child of buildercxt,  and switch to it just before GetValue()
(resetit just before  switching).  Then, don't worry about leaks in GetValue.  This way,  the text* conversions et al
don'tmatter.
 

After that I think we're going to need to get this working on top of
Andres' changes.  Which I'm afraid is going to be rather major surgery,
but I haven't looked.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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