Re: xmlelement AND timestamps.

Lynn Dobbs <lynn.dobbs@xxxxxxxxxxxxxx> · Tue, 14 Feb 2017 10:12:07 -0800



    Well, I couldn't reproduce allowing infinite timestamps in 9.2.4
      either. 

    
    While fixing some other minor issues that came up in the
      migration to 9.6.1, I copied a replaced good functions with bad
      ones.
    The good functions called another function when putting my
      starting,ending columns in xml.  That function dates the timestamp
      or date and formats it and converts to text.
    The documentation does say, "The particular behavior for
      individual data types is expected to evolve in order to align the
      SQL and PostgreSQL data types with the XML Schema specification,
      ...."  I didn't go chasing that down.  My bad.
    My bad functions were written using the xml2 extension that
      treated the xml as text rather than "real" xml.  

    
    Lynn Dobbs
Chief Technical Office
CreditLink Corporation
858-496-1000 x 103
    On 02/13/2017 06:10 PM, David G.
      Johnston wrote:

    
        On Mon, Feb 13, 2017 at
            6:36 PM, Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote:

        
            On
                02/13/2017 02:56 PM, Lynn Dobbs wrote:

                
                  I just migrated from 9.2.4 to 9.6.1 and had several
                  user created

                  functions fail.

                  
                  Recreating the failure with "SELECT xmlelement(name
                  foo,

                  'infinity'::timestamp)

                  ERROR: timestamp out of range

                  DETAIL: XML does not support infinite timestamp
                  values.

                  
                  I don't find anything in the documentation that
                  explains this.  I

                  consider this a regression.

                
              All I could find was this thread from 2009:

              
              https://www.postgresql.org/message-id/41F26B729B014C3E8F20F5B7%40teje

              
              which indicated it was fixed at that time.
            

            Actually,
              the cause of said commit (circa 2009) is that xmlelements
              were failing but xmlattributes were not...which makes me
              wonder how a 9.2 era release (circa 2012) supposedly
              worked with the submitted _expression_.
            

            The basic
              answer is that the XML data type is defined by standard
              and we attempt to conform to the standard.  In order to do
              so we must disallow infinite timestamps even though we
              accept them in SQL.
            

            I just
              tested the OP query on 9.0.x and 9.4.x and get the same
              error on both.
            

            There'd be
              a bit more sympathy if the OP were complaining about a
              patch release changing behavior - bug fix or not - but
              since the complaint involves going from 9.2 to 9.6 on its
              face this is an allowed behavior change regardless of the
              history.
            

            However,
              feel free to make a straight argument for accepting
              infinite timestamps and thus go above-and-beyond the
              relevant standards.  Personally this seems like a
              not-so-useful restriction on our implementation.  Let the
              user decide whether they want to deviate from the standard
              and risk cross-system incompatibilities.  XML itself is
              textual and we don't have any internal support for DTD or
              Schema as it is so I'm not sure what material benefit we
              gain by restraining ourselves here.
            

            David J.