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Merge Expressions in QueryPlan.

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This commit is contained in:
Nikolai Kochetov 2020-11-26 22:09:42 +03:00
parent c975f8156a
commit c42cc8f1ff
1 changed files with 27 additions and 0 deletions
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27
src/Processors/QueryPlan/QueryPlan.cpp
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@ -484,6 +484,29 @@ static void tryLiftUpArrayJoin(QueryPlan::Node * parent_node, QueryPlan::Node *
: filter_step->updateInputStream(array_join_step->getOutputStream(), true);
}
static bool tryMergeExpressions(QueryPlan::Node * parent_node, QueryPlan::Node * child_node)
{
auto & parent = parent_node->step;
auto & child = child_node->step;
auto * parent_expr = typeid_cast<ExpressionStep *>(parent.get());
auto * child_expr = typeid_cast<ExpressionStep *>(child.get());
if (parent_expr && child_expr)
{
auto merged = ActionsDAG::merge(std::move(*child_expr->getExpression()),
std::move(*parent_expr->getExpression()));
auto expr = std::make_unique<ExpressionStep>(child_expr->getInputStreams().front(), merged);
expr->setStepDescription(parent_expr->getStepDescription() + " + " + child_expr->getStepDescription());
parent_node->step = std::move(expr);
parent_node->children.swap(child_node->children);
return true;
}
return false;
}
void QueryPlan::optimize()
{
struct Frame
@ -503,7 +526,11 @@ void QueryPlan::optimize()
{
/// First entrance, try push down.
if (frame.node->children.size() == 1)
{
tryPushDownLimit(frame.node->step, frame.node->children.front());
while (tryMergeExpressions(frame.node, frame.node->children.front()));
}
}
if (frame.next_child < frame.node->children.size())