Looks like a there's a call to SvSETMAGIC missing in DBI or DBD::ODBC. Just to confirm, does the following cause length to return the correct length? 
$txt=$txt;

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By the way, using constant SQL_WCHAR would be clearer than using -8.

In reply to Re: length() returns wrong result - suspicious magic by ikegami
in thread length() returns wrong result - suspicious magic by mje

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