/* This file is part of VoltDB.
* Copyright (C) 2008-2014 VoltDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with VoltDB. If not, see <http://www.gnu.org/licenses/>.
*/
package org.voltdb.plannodes;
import java.util.ArrayList;
import java.util.List;
import org.json_voltpatches.JSONArray;
import org.json_voltpatches.JSONException;
import org.json_voltpatches.JSONObject;
import org.json_voltpatches.JSONStringer;
import org.voltdb.catalog.Cluster;
import org.voltdb.catalog.Database;
import org.voltdb.compiler.DatabaseEstimates;
import org.voltdb.compiler.ScalarValueHints;
import org.voltdb.expressions.AbstractExpression;
import org.voltdb.expressions.ExpressionUtil;
import org.voltdb.expressions.TupleValueExpression;
import org.voltdb.types.PlanNodeType;
import org.voltdb.types.SortDirectionType;
public class OrderByPlanNode extends AbstractPlanNode {
public enum Members {
SORT_COLUMNS,
SORT_EXPRESSION,
SORT_DIRECTION;
}
protected List<AbstractExpression> m_sortExpressions = new ArrayList<AbstractExpression>();
/**
* Sort Directions
*/
protected List<SortDirectionType> m_sortDirections = new ArrayList<SortDirectionType>();
public OrderByPlanNode() {
super();
}
@Override
public PlanNodeType getPlanNodeType() {
return PlanNodeType.ORDERBY;
}
@Override
public void validate() throws Exception {
super.validate();
// Make sure that they have the same # of columns and directions
if (m_sortExpressions.size() != m_sortDirections.size()) {
throw new Exception("ERROR: PlanNode '" + toString() + "' has " +
"'" + m_sortExpressions.size() + "' sort expressions but " +
"'" + m_sortDirections.size() + "' sort directions");
}
// Make sure that none of the items are null
for (int ctr = 0, cnt = m_sortExpressions.size(); ctr < cnt; ctr++) {
if (m_sortExpressions.get(ctr) == null) {
throw new Exception("ERROR: PlanNode '" + toString() + "' has a null " +
"sort expression at position " + ctr);
} else if (m_sortDirections.get(ctr) == null) {
throw new Exception("ERROR: PlanNode '" + toString() + "' has a null " +
"sort direction at position " + ctr);
}
}
}
/**
* Add a sort to the order-by
* @param sortExpr The input expression on which to order the rows
* @param sortDir
*/
public void addSort(AbstractExpression sortExpr, SortDirectionType sortDir)
{
assert(sortExpr != null);
// PlanNodes all need private deep copies of expressions
// so that the resolveColumnIndexes results
// don't get bashed by other nodes or subsequent planner runs
m_sortExpressions.add((AbstractExpression) sortExpr.clone());
m_sortDirections.add(sortDir);
}
public int countOfSortExpressions() {
return m_sortExpressions.size();
}
public List<AbstractExpression> getSortExpressions() {
return m_sortExpressions;
}
@Override
public void resolveColumnIndexes()
{
// Need to order and resolve indexes of output columns AND
// the sort columns
assert(m_children.size() == 1);
m_children.get(0).resolveColumnIndexes();
NodeSchema input_schema = m_children.get(0).getOutputSchema();
for (SchemaColumn col : m_outputSchema.getColumns())
{
// At this point, they'd better all be TVEs.
assert(col.getExpression() instanceof TupleValueExpression);
TupleValueExpression tve = (TupleValueExpression)col.getExpression();
int index = tve.resolveColumnIndexesUsingSchema(input_schema);
tve.setColumnIndex(index);
}
m_outputSchema.sortByTveIndex();
// Find the proper index for the sort columns. Not quite
// sure these should be TVEs in the long term.
List<TupleValueExpression> sort_tves =
new ArrayList<TupleValueExpression>();
for (AbstractExpression sort_exps : m_sortExpressions)
{
sort_tves.addAll(ExpressionUtil.getTupleValueExpressions(sort_exps));
}
for (TupleValueExpression tve : sort_tves)
{
int index = tve.resolveColumnIndexesUsingSchema(input_schema);
tve.setColumnIndex(index);
}
}
@Override
public void computeCostEstimates(long childOutputTupleCountEstimate,
Cluster cluster,
Database db,
DatabaseEstimates estimates,
ScalarValueHints[] paramHints)
{
// This method doesn't do anything besides what the parent method does,
// but it is a nice place to put a comment. Really, sorts should be pretty
// expensive and they're not costed as such yet because sometimes that
// backfires in our simplistic model.
//
// What's really interesting here is costing an index scan who has sorted
// output vs. an index scan that filters out a bunch of tuples, but still
// requires a sort. Which is best depends on how well the filter reduces the
// number of tuples, and that's not possible for us to know right now.
// The index scanner cost has been pretty carefully set up to do what we think
// we want, given the lack of table stats.
m_estimatedOutputTupleCount = childOutputTupleCountEstimate;
m_estimatedProcessedTupleCount = childOutputTupleCountEstimate;
}
@Override
public void toJSONString(JSONStringer stringer) throws JSONException {
super.toJSONString(stringer);
assert (m_sortExpressions.size() == m_sortDirections.size());
stringer.key(Members.SORT_COLUMNS.name()).array();
for (int ii = 0; ii < m_sortExpressions.size(); ii++) {
stringer.object();
stringer.key(Members.SORT_EXPRESSION.name());
stringer.object();
m_sortExpressions.get(ii).toJSONString(stringer);
stringer.endObject();
stringer.key(Members.SORT_DIRECTION.name()).value(m_sortDirections.get(ii).toString());
stringer.endObject();
}
stringer.endArray();
}
@Override
public void loadFromJSONObject( JSONObject jobj, Database db ) throws JSONException {
helpLoadFromJSONObject(jobj, db);
JSONArray jarray = null;
if( !jobj.isNull(Members.SORT_COLUMNS.name()) ){
jarray = jobj.getJSONArray( Members.SORT_COLUMNS.name() );
}
int size = jarray.length();
for( int i = 0; i < size; i++ ) {
JSONObject tempObj = jarray.getJSONObject(i);
m_sortDirections.add( SortDirectionType.get(tempObj.getString( Members.SORT_DIRECTION.name())) );
m_sortExpressions.add( AbstractExpression.fromJSONChild(tempObj, Members.SORT_EXPRESSION.name()) );
}
}
@Override
protected String explainPlanForNode(String indent) {
return "ORDER BY (SORT)";
}
}