Re: Seamless replacement to MySQL's GROUP_CONCAT function... - Mailing list pgsql-general

From immersive.excel@gmail.com
Subject Re: Seamless replacement to MySQL's GROUP_CONCAT function...
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Msg-id 51FFE994.8050701@gmail.com
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In response to Re: Seamless replacement to MySQL's GROUP_CONCAT function...  (Richard Broersma <richard.broersma@gmail.com>)
Responses Re: Seamless replacement to MySQL's GROUP_CONCAT function...
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    I believe his VARIADIC might cover the optional delimiter use, but
    he suggests using an array aggregation function instead -which does
    not return a string list, so you would still have to rework the
    original queries.

    Now you could write a GROUP_CONCAT aggregate that uses a final
    function to convert the array to a string list -but correct me if
    I'm wrong, I believe the way I am concatenating as I go uses less
    resources (an array of, say, 5000 elements versus a string...)

    But while I am testing use of the ANYELEMENT, I will see if VARIADIC
    can simplify things a tad more...

    ========================
    On 08/05/2013 01:15 PM, Richard Broersma wrote:
    <blockquote
cite="mid:CABvLTWEZyie9+zZZ9+xJNgaPsNLOL=OfOn2KROSrbryyQY2QEg@mail.gmail.com"
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        For posterity that finalized function could be posted here:

          <a moz-do-not-send="true"

href="http://okbob.blogspot.com/2009/08/mysql-functions-for-postgresql.html">http://okbob.blogspot.com/2009/08/mysql-functions-for-postgresql.html 



        There's already a GROUP_CONCAT, listed there, but I guess this
        one was lacking in some way.



        On Mon, Aug 5, 2013 at 10:04 AM, Alvaro Herrera <<a
              moz-do-not-send="true"
              href="mailto:alvherre@2ndquadrant.com">alvherre@2ndquadrant.com>
          wrote:
          <a moz-do-not-send="true"
              href="mailto:immersive.excel@gmail.com">immersive.excel@gmail.com
            escribió:

              >     Note: I found some close-but-no cigar aggregates
              shared online, but
              >     they would not accept integer arguments, nor
              would they handle the
              >     optionally furnished delimiter. People would
              suggesting casting the
              >     argument to the pseudo-GROUP_CONCAT. Again:
              Rewrite perhaps hundreds

            >     of queries?<br>

            I don't think you need all the variations; you should be
            able to make
            them all work with a single set of functions, taking
            ANYELEMENT instead
            of text/int8/int4 etc.


              --
              Álvaro Herrera                <a moz-do-not-send="true"
                href="http://www.2ndQuadrant.com/">http://www.2ndQuadrant.com/
              PostgreSQL Development, 24x7 Support, Training &
              Services


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        Richard Broersma Jr.

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