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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mongo/db/query/query_planner.h"
#include "mongo/db/query/query_solution.h"
#include "mongo/db/matcher/expression_parser.h"
namespace mongo {
// static
void QueryPlanner::plan(const CanonicalQuery& query, vector<QuerySolution*> *out) {
const MatchExpression* root = query.root();
// TODO: If pq.hasOption(QueryOption_OplogReplay) use FindingStartCursor equivalent which
// must be translated into stages.
// The default plan is always a collection scan with a heavy filter. This is a valid
// solution for any query that does not require an index.
if (!requiresIndex(root)) {
auto_ptr<QuerySolution> soln(new QuerySolution());
soln->filterData = query.getQueryObj();
// TODO: have a MatchExpression::copy function(?)
StatusWithMatchExpression swme = MatchExpressionParser::parse(soln->filterData);
verify(swme.isOK());
soln->filter.reset(swme.getValue());
// Make the (only) node, a collection scan.
CollectionScanNode* csn = new CollectionScanNode();
csn->name = query.ns();
csn->filter = soln->filter.get();
// Add this solution to the list of solutions.
soln->root.reset(csn);
out->push_back(soln.release());
// TODO: limit and skip
// TODO: sort.
}
}
// static
bool QueryPlanner::requiresIndex(const MatchExpression* node) {
if (MatchExpression::GEO_NEAR == node->matchType()) {
return true;
}
for (size_t i = 0; i < node->numChildren(); ++i) {
if (requiresIndex(node->getChild(i))) {
return true;
}
}
return false;
}
} // namespace mongo
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