parallel pg installation and functions gotcha

I've just spent a day trying to migrate my databases from 7.1 to 7.3.2.  Th=
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only problem has been that every time a function was called, I got the=20
following error:

  FATAL:  Pre-7.3 object file made an elog() call.  Recompile.

The problem, I now realize, is that the output of pg_dumpall contains lines=
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like=20

CREATE FUNCTION plpgsql_call_handler () RETURNS opaque
    AS '/usr/local/lib/plpgsql.so', 'plpgsql_call_handler'
    LANGUAGE "C";

However, my approach to upgrading involved installing a parallel copy of th=
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pg binaries, in a directory other than /usr/local/.  So my functions were,=
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apparently, using the 7.1 plpgsql.so.

My solution: switch the lines in the output of pg_dumpall to point to the=
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current plpgsql.so, and restore normally. Everything works now.

A caution in INSTALL's 'If You Are Upgrading' section might be useful for=
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others trying to have two different sets of binaries on the same machine.