See my prior reply to Philip: the problem is that the given string is
longer than NAMEDATALEN. When you writerulename = 'foo'
(rulename is of type NAME) the untyped literal string 'foo' gets coerced
to NAME, ie truncated to fit, and all is well. When you writerulename = ('foo' || 'bar')
the result of the || operator is type TEXT, so instead rulename is
converted to TEXT and a text comparison is performed. In this case the
righthand value is not truncated and so the match will always fail.
regards, tom lane
