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First version of fix for LIMIT cost estimation.

This commit is contained in:
Max Neunhoeffer 2014-11-23 21:53:25 +01:00 committed by Frank Celler
parent 4ce5575eb3
commit d889974ad4
1 changed files with 2 additions and 18 deletions
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20
arangod/Aql/ExecutionNode.cpp
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@ -1538,24 +1538,8 @@ void LimitNode::toJsonHelper (triagens::basics::Json& nodes,
double LimitNode::estimateCost (size_t& nrItems) const {
size_t incoming = 0;
double depCost = _dependencies.at(0)->getCost(incoming);
if (incoming >= _offset + _limit) {
// We will actually only ask for _offset + _limit and hand
// on _limit:
nrItems = _limit;
return depCost * (_offset + _limit) / incoming + _limit;
}
else {
// We will only get less than we need, but at the full cost
// for the dependencies:
if (incoming >= _offset) {
nrItems = incoming - _offset;
return depCost + nrItems;
}
else {
nrItems = 0;
return depCost;
}
}
nrItems = std::min(_limit, std::max(0, incoming - _offset));
return depCost + nrItems;
}
// -----------------------------------------------------------------------------