Re: patch: function xmltable

Something I just noticed is that transformTableExpr takes a TableExpr
node and returns another TableExpr node.  That's unlike what we do in
other places, where the node returned is of a different type than the
input node.  I'm not real clear what happens if you try to re-transform
a node that was already transformed, but it seems worth thinking about.

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