docs: protected StmtSubqueryScan addSubqueryToStmtCache(
              AbstractParsedStmt subquery, String tableAlias) {
          assert(subquery != null);
          // If there is no usable alias because the subquery is inside an expression,
          // generate a unique one for internal use.
          if (tableAlias == null) {
              tableAlias = AbstractParsedStmt.TEMP_TABLE_NAME + "_" + subquery.m_stmtId;
          }
          StmtSubqueryScan subqueryScan =
                  new StmtSubqueryScan(subquery, tableAlias, m_stmtId);
          StmtTableScan prior = m_tableAliasMap.put(tableAlias, subqueryScan);
          assert(prior == null);
          return subqueryScan;
      }