function cleanValueTables()
{
/* lock */
if (!$this->store->getLock()) {
return $this->addError('Could not get lock in "cleanValueTables"');
}
$con = $this->store->getDBCon();
$tbl_prefix = $this->store->getTablePrefix();
$dbv = $this->store->getDBVersion();
/* o2val */
$sql = $dbv < '04-01' ? 'DELETE ' . $tbl_prefix . 'o2val' : 'DELETE V';
$sql .= '
FROM ' . $tbl_prefix . 'o2val V
LEFT JOIN ' . $tbl_prefix . 'triple T ON (T.o = V.id)
WHERE T.t IS NULL
';
mysqli_query($con, $sql);
/* s2val */
$sql = $dbv < '04-01' ? 'DELETE ' . $tbl_prefix . 's2val' : 'DELETE V';
$sql .= '
FROM ' . $tbl_prefix . 's2val V
LEFT JOIN ' . $tbl_prefix . 'triple T ON (T.s = V.id)
WHERE T.t IS NULL
';
mysqli_query($con, $sql);
/* id2val */
$sql = $dbv < '04-01' ? 'DELETE ' . $tbl_prefix . 'id2val' : 'DELETE V';
$sql .= '
FROM ' . $tbl_prefix . 'id2val V
LEFT JOIN ' . $tbl_prefix . 'g2t G ON (G.g = V.id)
LEFT JOIN ' . $tbl_prefix . 'triple T1 ON (T1.p = V.id)
LEFT JOIN ' . $tbl_prefix . 'triple T2 ON (T2.o_lang_dt = V.id)
WHERE G.g IS NULL AND T1.t IS NULL AND T2.t IS NULL
';
//mysql_query($sql, $con);
/* release lock */
$this->store->releaseLock();
}