# Build a large XML document, bind it as a CLOB,
# extract elements through PL/SQL and return as a CLOB

# $dbh is a connected database handle
# output will be large

local $dbh->{LongReadLen} = 1_000_000;

my $in_clob = "<document>\n";
$in_clob .= "  <value>$_</value>\n" for 1 .. 10_000;
$in_clob .= "</document>\n";

my $out_clob;

my $sth = $dbh->prepare(<<PLSQL_END);
-- extract 'value' nodes
DECLARE
	x XMLTYPE := XMLTYPE(:in);
BEGIN
	:out := x.extract('/document/value').getClobVal();
END;

PLSQL_END

# :in param will be converted to a temp lob
# :out parameter will be returned as a string.

$sth->bind_param( ':in', $in_clob, { ora_type => ORA_CLOB } );
$sth->bind_param_inout( ':out', \$out_clob, 0, { ora_type => ORA_CLOB } );
$sth->execute;