/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Nov 27, 2011
*/
package com.bigdata.rdf.sparql.ast.hints;
import com.bigdata.rdf.sparql.ast.ASTBase;
import com.bigdata.rdf.sparql.ast.FilterExistsModeEnum;
import com.bigdata.rdf.sparql.ast.FilterNode;
import com.bigdata.rdf.sparql.ast.IQueryNode;
import com.bigdata.rdf.sparql.ast.IValueExpressionNode;
import com.bigdata.rdf.sparql.ast.JoinGroupNode;
import com.bigdata.rdf.sparql.ast.QueryHints;
import com.bigdata.rdf.sparql.ast.QueryRoot;
import com.bigdata.rdf.sparql.ast.StaticAnalysis;
import com.bigdata.rdf.sparql.ast.SubqueryFunctionNodeBase;
import com.bigdata.rdf.sparql.ast.eval.AST2BOpContext;
/**
* Used to specify the query plan for FILTER (NOT) EXISTS. There are two basic
* plans: vectored sub-plan and subquery with LIMIT ONE. Each plan has its
* advantages.
*
* @see FilterExistsModeEnum
* @see <a href="http://trac.blazegraph.com/ticket/988"> bad performance for FILTER
* EXISTS </a>
*/
final class FilterExistsHint extends AbstractQueryHint<FilterExistsModeEnum> {
protected FilterExistsHint() {
super(QueryHints.FILTER_EXISTS,
QueryHints.DEFAULT_FILTER_EXISTS);
}
@Override
public void handle(final AST2BOpContext context,
final QueryRoot queryRoot,
final QueryHintScope scope, final ASTBase op,
final FilterExistsModeEnum value) {
if (op instanceof JoinGroupNode
&& ((JoinGroupNode) op).getParent() == null) {
/*
* This is the top-level join group inside of the FILTER. It does
* not have a direct parent. We resolve the parent ExistsNode or
* NotExistsNode by searching from the top-level query root.
*/
final JoinGroupNode filterGroup = (JoinGroupNode) op;
final IQueryNode p = StaticAnalysis.findParent(queryRoot,
filterGroup);
if (p instanceof FilterNode) {
final IValueExpressionNode n = ((FilterNode) p)
.getValueExpressionNode();
if (n instanceof SubqueryFunctionNodeBase) {
((SubqueryFunctionNodeBase) n).setFilterExistsMode(value);
}
}
// _setAnnotation(context, scope, op, getName(), value);
}
}
@Override
public FilterExistsModeEnum validate(final String value) {
return FilterExistsModeEnum.valueOf(value);
}
}