private bool TryOptimizeIN(SelectASTNode selectASTNode, ReadLogicalElement input, TableDefinition tableDefinition, out CartesianProductElement result)
{
if (selectASTNode.Condition is RelOpASTNode relOpASTNode &&
relOpASTNode.RelationOperator == Compiler.Common.RelOp.In)
{
SelectASTNode innerSelectASTNode = null;
IdentifierASTNode outerIdentifierASTNode = null;
if (relOpASTNode.Right is SelectASTNode)
{
innerSelectASTNode = (SelectASTNode)relOpASTNode.Right;
if (relOpASTNode.Left is IdentifierASTNode)
{
outerIdentifierASTNode = (IdentifierASTNode)relOpASTNode.Left;
}
}
if (relOpASTNode.Right is IdentifierASTNode)
{
outerIdentifierASTNode = (IdentifierASTNode)relOpASTNode.Right;
if (relOpASTNode.Left is SelectASTNode)
{
innerSelectASTNode = (SelectASTNode)relOpASTNode.Left;
}
}
if (innerSelectASTNode != null &&
outerIdentifierASTNode != null)
{
result = new CartesianProductElement(input, GetElementForTreeNode(innerSelectASTNode) as ReadLogicalElement, GetColumnFromIdentifierNode(tableDefinition, outerIdentifierASTNode), SelectColumnsToColumns(_relationManager.GetTable(innerSelectASTNode.From.Identifier.Identifier), innerSelectASTNode.SelectColumns).First().AttributeDefinition);
return(true);
}
}
result = null;
return(false);
}
private LogicalElement GetElementForTreeNode(SyntaxTreeNode node)
{
if (node is SelectASTNode selectASTNode)
{
Table table = _relationManager.GetTable(selectASTNode.From.Identifier.Identifier);
ReadLogicalElement result = new RelationElement(table.TableDefinition);
Condition condition = null;
if (selectASTNode.Condition != null)
{
condition = BooleanExpressionToCondition(table.TableDefinition, selectASTNode.Condition);
//// todo: IN (1,2,3)
//// todo: IN (select id from products) AND x = 1
//if (TryOptimizeIN(selectASTNode, result, table.TableDefinition, out CartesianProductElement productElement))
//{
// result = productElement;
//}
//else
//{
//}
}
if (selectASTNode.Join != null)
{
Join join = JoinNodeToJoin(table.TableDefinition, selectASTNode.Join);
ReadLogicalElement joinRelation = new RelationElement(join.RightTable);
if (condition != null)
{
(Condition leftPushedDownCondition, Condition leftover1) = TryPushdown((RelationElement)result, condition);
(Condition rightPushedDownCondition, Condition leftover2) = TryPushdown((RelationElement)joinRelation, leftover1);
leftPushedDownCondition = leftPushedDownCondition.Simplify();
rightPushedDownCondition = rightPushedDownCondition.Simplify();
condition = leftover2?.Simplify();
if (leftPushedDownCondition != null)
{
result = new SelectionElement(result, leftPushedDownCondition);
}
if (rightPushedDownCondition != null)
{
joinRelation = new SelectionElement(joinRelation, rightPushedDownCondition);
}
}
else
{
result = new RelationElement(table.TableDefinition);
joinRelation = new RelationElement(join.RightTable);
}
result = new CartesianProductElement(result, joinRelation, join.LeftColumn, join.RightColumn);
}
else
{
result = new RelationElement(table.TableDefinition);
}
if (condition != null)
{
result = new SelectionElement(result, condition);
}
result = new ProjectionElement(result, SelectColumnsToColumns(table, selectASTNode.SelectColumns));
return(result);
}
else if (node is InsertASTNode insertASTNode)
{
Table table = _relationManager.GetTable(insertASTNode.Into.Identifier);
Set set = new Set(table.TableDefinition);
set.Add(insertASTNode.Arguments.Select(x => GetValueFromFactor(x)).ToArray());
return(new InsertElement(table.TableDefinition, new MemorySetElement(table.TableDefinition, set)));
}
return(null);
}