private void pushOrderingDown(ResultSetNode rsn) throws StandardException {
ContextManager cm = getContextManager();
NodeFactory nf = getNodeFactory();
OrderByList orderByList = (OrderByList) nf.getNode(C_NodeTypes.ORDER_BY_LIST, cm);
for (int i = 0; i < intermediateOrderByColumns.length; i++) {
OrderByColumn orderByColumn =
(OrderByColumn)
nf.getNode(
C_NodeTypes.ORDER_BY_COLUMN,
nf.getNode(
C_NodeTypes.INT_CONSTANT_NODE,
ReuseFactory.getInteger(intermediateOrderByColumns[i] + 1),
cm),
cm);
if (intermediateOrderByDirection[i] < 0) orderByColumn.setDescending();
if (intermediateOrderByNullsLow[i]) orderByColumn.setNullsOrderedLow();
orderByList.addOrderByColumn(orderByColumn);
}
orderByList.bindOrderByColumns(rsn);
rsn.pushOrderByList(orderByList);
} // end of pushOrderingDown
/**
* Preprocess a ResultSetNode - this currently means: o Generating a referenced table map for each
* ResultSetNode. o Putting the WHERE and HAVING clauses in conjunctive normal form (CNF). o
* Converting the WHERE and HAVING clauses into PredicateLists and classifying them. o Ensuring
* that a ProjectRestrictNode is generated on top of every FromBaseTable and generated in place of
* every FromSubquery. o Pushing single table predicates down to the new ProjectRestrictNodes.
*
* @param numTables The number of tables in the DML Statement
* @param gbl The group by list, if any
* @param fromList The from list, if any
* @return ResultSetNode at top of preprocessed tree.
* @exception StandardException Thrown on error
*/
public ResultSetNode preprocess(int numTables, GroupByList gbl, FromList fromList)
throws StandardException {
// Push the order by list down to the ResultSet
if (orderByList != null) {
// If we have more than 1 ORDERBY columns, we may be able to
// remove duplicate columns, e.g., "ORDER BY 1, 1, 2".
if (orderByList.size() > 1) {
orderByList.removeDupColumns();
}
subquery.pushOrderByList(orderByList);
orderByList = null;
}
subquery.pushOffsetFetchFirst(offset, fetchFirst, hasJDBClimitClause);
/* We want to chop out the FromSubquery from the tree and replace it
* with a ProjectRestrictNode. One complication is that there may be
* ColumnReferences above us which point to the FromSubquery's RCL.
* What we want to return is a tree with a PRN with the
* FromSubquery's RCL on top. (In addition, we don't want to be
* introducing any redundant ProjectRestrictNodes.)
* Another complication is that we want to be able to only push
* projections and restrictions down to this ProjectRestrict, but
* we want to be able to push them through as well.
* So, we:
* o call subquery.preprocess() which returns a tree with
* a SelectNode or a RowResultSetNode on top.
* o If the FSqry is flattenable(), then we return (so that the
* caller can then call flatten()), otherwise we:
* o generate a PRN, whose RCL is the FSqry's RCL, on top of the result.
* o create a referencedTableMap for the PRN which represents
* the FSqry's tableNumber, since ColumnReferences in the outer
* query block would be referring to that one.
* (This will allow us to push restrictions down to the PRN.)
*/
subquery = subquery.preprocess(numTables, gbl, fromList);
/* Return if the FSqry is flattenable()
* NOTE: We can't flatten a FromSubquery if there is a group by list
* because the group by list must be ColumnReferences. For:
* select c1 from v1 group by c1,
* where v1 is select 1 from t1
* The expression under the last redundant ResultColumn is an IntConstantNode,
* not a ColumnReference.
* We also do not flatten a subquery if tableProperties is non-null,
* as the user is specifying 1 or more properties for the derived table,
* which could potentially be lost on the flattening.
* RESOLVE - this is too restrictive.
*/
if ((gbl == null || gbl.size() == 0)
&& tableProperties == null
&& subquery.flattenableInFromSubquery(fromList)) {
/* Set our table map to the subquery's table map. */
setReferencedTableMap(subquery.getReferencedTableMap());
return this;
}
return extractSubquery(numTables);
}