/// <summary>
/// Plans an ORDER BY set.
/// </summary>
/// <param name="plan"></param>
/// <param name="orderBy"></param>
/// <param name="fromSet"></param>
/// <param name="selectedColumns"></param>
/// <remarks>
/// This is given its own function because we may want to plan
/// this at the end of a number of composite functions.
/// </remarks>
/// <returns></returns>
private static IQueryPlanNode PlanForOrderBy(IQueryPlanNode plan, IList <ByColumn> orderBy, TableExpressionFromSet fromSet, IList <SelectColumn> selectedColumns)
{
var functionTable = new ObjectName("FUNCTIONTABLE");
// Sort on the ORDER BY clause
if (orderBy.Count > 0)
{
int sz = orderBy.Count;
var orderList = new ObjectName[sz];
var ascendingList = new bool[sz];
var functionOrders = new List <Expression>();
for (int i = 0; i < sz; ++i)
{
ByColumn column = orderBy[i];
Expression exp = column.Expression;
ascendingList[i] = column.Ascending;
ObjectName v = exp.AsVariable();
if (v != null)
{
ObjectName newV = fromSet.ResolveReference(v);
if (newV == null)
{
throw new ApplicationException("Can not resolve ORDER BY variable: " + v);
}
newV = SubstituteAliasedVariable(newV, selectedColumns);
orderList[i] = newV;
}
else
{
// Otherwise we must be ordering by an expression such as
// '0 - a'.
// Resolve the expression,
exp = exp.Prepare(fromSet.ExpressionQualifier);
// Make sure we substitute any aliased columns in the order by
// columns.
exp = SubstituteAliasedVariables(exp, selectedColumns);
// The new ordering functions are called 'FUNCTIONTABLE.#ORDER-n'
// where n is the number of the ordering expression.
orderList[i] = new ObjectName(functionTable, "#ORDER-" + functionOrders.Count);
functionOrders.Add(exp);
}
}
// If there are functional orderings,
// For this we must define a new FunctionTable with the expressions,
// then order by those columns, and then use another SubsetNode
// command node.
int fsz = functionOrders.Count;
if (fsz > 0)
{
var funs = new Expression[fsz];
var fnames = new String[fsz];
for (int n = 0; n < fsz; ++n)
{
funs[n] = functionOrders[n];
fnames[n] = "#ORDER-" + n;
}
if (plan is SubsetNode)
{
// If the top plan is a QueryPlan.SubsetNode then we use the
// information from it to create a new SubsetNode that
// doesn't include the functional orders we have attached here.
var topSubsetNode = (SubsetNode)plan;
ObjectName[] mappedNames = topSubsetNode.NewColumnNames;
// Defines the sort functions
plan = new CreateFunctionsNode(plan, funs, fnames);
// Then plan the sort
plan = new SortNode(plan, orderList, ascendingList);
// Then plan the subset
plan = new SubsetNode(plan, mappedNames, mappedNames);
}
else
{
// Defines the sort functions
plan = new CreateFunctionsNode(plan, funs, fnames);
// Plan the sort
plan = new SortNode(plan, orderList, ascendingList);
}
}
else
{
// No functional orders so we only need to sort by the columns
// defined.
plan = new SortNode(plan, orderList, ascendingList);
}
}
return(plan);
}
/// <summary>
/// Plans an ORDER BY set.
/// </summary>
/// <param name="plan"></param>
/// <param name="orderBy"></param>
/// <param name="fromSet"></param>
/// <param name="selectedColumns"></param>
/// <remarks>
/// This is given its own function because we may want to plan
/// this at the end of a number of composite functions.
/// </remarks>
/// <returns></returns>
private static IQueryPlanNode PlanForOrderBy(IQueryPlanNode plan, IList<ByColumn> orderBy, TableExpressionFromSet fromSet, IList<SelectColumn> selectedColumns)
{
var functionTable = new ObjectName("FUNCTIONTABLE");
// Sort on the ORDER BY clause
if (orderBy.Count > 0) {
int sz = orderBy.Count;
var orderList = new ObjectName[sz];
var ascendingList = new bool[sz];
var functionOrders = new List<Expression>();
for (int i = 0; i < sz; ++i) {
ByColumn column = orderBy[i];
Expression exp = column.Expression;
ascendingList[i] = column.Ascending;
ObjectName v = exp.AsVariable();
if (v != null) {
ObjectName newV = fromSet.ResolveReference(v);
if (newV == null)
throw new ApplicationException("Can not resolve ORDER BY variable: " + v);
newV = SubstituteAliasedVariable(newV, selectedColumns);
orderList[i] = newV;
} else {
// Otherwise we must be ordering by an expression such as
// '0 - a'.
// Resolve the expression,
exp = exp.Prepare(fromSet.ExpressionQualifier);
// Make sure we substitute any aliased columns in the order by
// columns.
exp = SubstituteAliasedVariables(exp, selectedColumns);
// The new ordering functions are called 'FUNCTIONTABLE.#ORDER-n'
// where n is the number of the ordering expression.
orderList[i] = new ObjectName(functionTable, "#ORDER-" + functionOrders.Count);
functionOrders.Add(exp);
}
}
// If there are functional orderings,
// For this we must define a new FunctionTable with the expressions,
// then order by those columns, and then use another SubsetNode
// command node.
int fsz = functionOrders.Count;
if (fsz > 0) {
var funs = new Expression[fsz];
var fnames = new String[fsz];
for (int n = 0; n < fsz; ++n) {
funs[n] = functionOrders[n];
fnames[n] = "#ORDER-" + n;
}
if (plan is SubsetNode) {
// If the top plan is a QueryPlan.SubsetNode then we use the
// information from it to create a new SubsetNode that
// doesn't include the functional orders we have attached here.
var topSubsetNode = (SubsetNode)plan;
ObjectName[] mappedNames = topSubsetNode.NewColumnNames;
// Defines the sort functions
plan = new CreateFunctionsNode(plan, funs, fnames);
// Then plan the sort
plan = new SortNode(plan, orderList, ascendingList);
// Then plan the subset
plan = new SubsetNode(plan, mappedNames, mappedNames);
} else {
// Defines the sort functions
plan = new CreateFunctionsNode(plan, funs, fnames);
// Plan the sort
plan = new SortNode(plan, orderList, ascendingList);
}
} else {
// No functional orders so we only need to sort by the columns
// defined.
plan = new SortNode(plan, orderList, ascendingList);
}
}
return plan;
}