synchronized (m_tableStatsData) {
TableStatistics stats = m_tableStatsData.get(catalog_tbl);
if (stats == null) {
stats = new TableStatistics(catalog_tbl);
stats.preprocess(catalogContext.database);
m_tableStatsData.put(catalog_tbl, stats);
}
vt.resetRowPosition();
while (vt.advanceRow()) {
VoltTableRow row = vt.getRow();