/// <summary>
/// Forms a command plan <see cref="IQueryPlanNode"/> from the given
/// <see cref="TableSelectExpression"/> and <see cref="TableExpressionFromSet"/>.
/// </summary>
/// <param name="db"></param>
/// <param name="expression">Describes the <i>SELECT</i> command
/// (or sub-command).</param>
/// <param name="fromSet">Used to resolve expression references.</param>
/// <param name="orderBy">A list of <see cref="ByColumn"/> objects
/// that represent an optional <i>ORDER BY</i> clause. If this is null
/// or the list is empty, no ordering is done.</param>
/// <returns></returns>
public static IQueryPlanNode FormQueryPlan(IDatabaseConnection db, TableSelectExpression expression, TableExpressionFromSet fromSet, IList <ByColumn> orderBy)
{
IQueryContext context = new DatabaseQueryContext(db);
// ----- Resolve the SELECT list
// If there are 0 columns selected, then we assume the result should
// show all of the columns in the result.
bool doSubsetColumn = (expression.Columns.Count != 0);
// What we are selecting
var columnSet = BuildColumnSet(expression, fromSet);
// Prepare the column_set,
columnSet.Prepare(context);
ResolveOrderByRefs(columnSet, orderBy);
// -----
// Set up plans for each table in the from clause of the command. For
// sub-queries, we recurse.
var tablePlanner = SetupPlanners(db, fromSet);
// -----
// The WHERE and HAVING clauses
FilterExpression whereClause = expression.Where;
FilterExpression havingClause = expression.Having;
whereClause = PrepareJoins(tablePlanner, expression, fromSet, whereClause);
// Prepare the WHERE and HAVING clause, qualifies all variables and
// prepares sub-queries.
whereClause = PrepareSearchExpression(db, fromSet, whereClause);
havingClause = PrepareSearchExpression(db, fromSet, havingClause);
// Any extra Aggregate functions that are part of the HAVING clause that
// we need to add. This is a list of a name followed by the expression
// that contains the aggregate function.
var extraAggregateFunctions = new List <Expression>();
if (havingClause != null && havingClause.Expression != null)
{
Expression newHavingClause = FilterHavingClause(havingClause.Expression, extraAggregateFunctions, context);
havingClause = new FilterExpression(newHavingClause);
}
// Any GROUP BY functions,
ObjectName[] groupByList;
IList <Expression> groupByFunctions;
var gsz = ResolveGroupBy(expression, fromSet, context, out groupByList, out groupByFunctions);
// Resolve GROUP MAX variable to a reference in this from set
ObjectName groupmaxColumn = ResolveGroupMax(expression, fromSet);
// -----
// Now all the variables should be resolved and correlated variables set
// up as appropriate.
// If nothing in the FROM clause then simply evaluate the result of the
// select
if (fromSet.SetCount == 0)
{
return(EvaluateSingle(columnSet));
}
// Plan the where clause. The returned node is the plan to evaluate the
// WHERE clause.
IQueryPlanNode node = tablePlanner.PlanSearchExpression(whereClause);
Expression[] defFunList;
string[] defFunNames;
var fsz = MakeupFunctions(columnSet, extraAggregateFunctions, out defFunList, out defFunNames);
node = PlanGroup(node, columnSet, groupmaxColumn, gsz, groupByList, groupByFunctions, fsz, defFunNames, defFunList);
// The result column list
List <SelectColumn> selectColumns = columnSet.SelectedColumns;
int sz = selectColumns.Count;
// Evaluate the having clause if necessary
if (havingClause != null && havingClause.Expression != null)
{
// Before we evaluate the having expression we must substitute all the
// aliased variables.
Expression havingExpr = havingClause.Expression;
havingExpr = SubstituteAliasedVariables(havingExpr, selectColumns);
havingClause = new FilterExpression(havingExpr);
PlanTableSource source = tablePlanner.SingleTableSource;
source.UpdatePlan(node);
node = tablePlanner.PlanSearchExpression(havingClause);
}
// Do we have a composite select expression to process?
IQueryPlanNode rightComposite = null;
if (expression.NextComposite != null)
{
TableSelectExpression compositeExpr = expression.NextComposite;
// Generate the TableExpressionFromSet hierarchy for the expression,
TableExpressionFromSet compositeFromSet = GenerateFromSet(compositeExpr, db);
// Form the right plan
rightComposite = FormQueryPlan(db, compositeExpr, compositeFromSet, null);
}
// Do we do a final subset column?
ObjectName[] aliases = null;
if (doSubsetColumn)
{
// Make up the lists
ObjectName[] subsetVars = new ObjectName[sz];
aliases = new ObjectName[sz];
for (int i = 0; i < sz; ++i)
{
SelectColumn scol = selectColumns[i];
subsetVars[i] = scol.InternalName.Clone();
aliases[i] = scol.Alias.Clone();
}
// If we are distinct then add the DistinctNode here
if (expression.Distinct)
{
node = new DistinctNode(node, subsetVars);
}
// Process the ORDER BY?
// Note that the ORDER BY has to occur before the subset call, but
// after the distinct because distinct can affect the ordering of the
// result.
if (rightComposite == null && orderBy != null)
{
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
}
// Rename the columns as specified in the SELECT
node = new SubsetNode(node, subsetVars, aliases);
}
else
{
// Process the ORDER BY?
if (rightComposite == null && orderBy != null)
{
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
}
}
// Do we have a composite to merge in?
if (rightComposite != null)
{
// For the composite
node = new CompositeNode(node, rightComposite,
expression.CompositeFunction, expression.IsCompositeAll);
// Final order by?
if (orderBy != null)
{
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
}
// Ensure a final subset node
if (!(node is SubsetNode) && aliases != null)
{
node = new SubsetNode(node, aliases, aliases);
}
}
return(node);
}
/// <summary>
/// Forms a command plan <see cref="IQueryPlanNode"/> from the given
/// <see cref="TableSelectExpression"/> and <see cref="TableExpressionFromSet"/>.
/// </summary>
/// <param name="db"></param>
/// <param name="expression">Describes the <i>SELECT</i> command
/// (or sub-command).</param>
/// <param name="fromSet">Used to resolve expression references.</param>
/// <param name="orderBy">A list of <see cref="ByColumn"/> objects
/// that represent an optional <i>ORDER BY</i> clause. If this is null
/// or the list is empty, no ordering is done.</param>
/// <returns></returns>
public static IQueryPlanNode FormQueryPlan(IDatabaseConnection db, TableSelectExpression expression, TableExpressionFromSet fromSet, IList<ByColumn> orderBy)
{
IQueryContext context = new DatabaseQueryContext(db);
// ----- Resolve the SELECT list
// If there are 0 columns selected, then we assume the result should
// show all of the columns in the result.
bool doSubsetColumn = (expression.Columns.Count != 0);
// What we are selecting
var columnSet = BuildColumnSet(expression, fromSet);
// Prepare the column_set,
columnSet.Prepare(context);
ResolveOrderByRefs(columnSet, orderBy);
// -----
// Set up plans for each table in the from clause of the command. For
// sub-queries, we recurse.
var tablePlanner = SetupPlanners(db, fromSet);
// -----
// The WHERE and HAVING clauses
FilterExpression whereClause = expression.Where;
FilterExpression havingClause = expression.Having;
whereClause = PrepareJoins(tablePlanner, expression, fromSet, whereClause);
// Prepare the WHERE and HAVING clause, qualifies all variables and
// prepares sub-queries.
whereClause = PrepareSearchExpression(db, fromSet, whereClause);
havingClause = PrepareSearchExpression(db, fromSet, havingClause);
// Any extra Aggregate functions that are part of the HAVING clause that
// we need to add. This is a list of a name followed by the expression
// that contains the aggregate function.
var extraAggregateFunctions = new List<Expression>();
if (havingClause != null && havingClause.Expression != null) {
Expression newHavingClause = FilterHavingClause(havingClause.Expression, extraAggregateFunctions, context);
havingClause = new FilterExpression(newHavingClause);
}
// Any GROUP BY functions,
ObjectName[] groupByList;
IList<Expression> groupByFunctions;
var gsz = ResolveGroupBy(expression, fromSet, context, out groupByList, out groupByFunctions);
// Resolve GROUP MAX variable to a reference in this from set
ObjectName groupmaxColumn = ResolveGroupMax(expression, fromSet);
// -----
// Now all the variables should be resolved and correlated variables set
// up as appropriate.
// If nothing in the FROM clause then simply evaluate the result of the
// select
if (fromSet.SetCount == 0)
return EvaluateSingle(columnSet);
// Plan the where clause. The returned node is the plan to evaluate the
// WHERE clause.
IQueryPlanNode node = tablePlanner.PlanSearchExpression(whereClause);
Expression[] defFunList;
string[] defFunNames;
var fsz = MakeupFunctions(columnSet, extraAggregateFunctions, out defFunList, out defFunNames);
node = PlanGroup(node, columnSet, groupmaxColumn, gsz, groupByList, groupByFunctions, fsz, defFunNames, defFunList);
// The result column list
List<SelectColumn> selectColumns = columnSet.SelectedColumns;
int sz = selectColumns.Count;
// Evaluate the having clause if necessary
if (havingClause != null && havingClause.Expression != null) {
// Before we evaluate the having expression we must substitute all the
// aliased variables.
Expression havingExpr = havingClause.Expression;
havingExpr = SubstituteAliasedVariables(havingExpr, selectColumns);
havingClause = new FilterExpression(havingExpr);
PlanTableSource source = tablePlanner.SingleTableSource;
source.UpdatePlan(node);
node = tablePlanner.PlanSearchExpression(havingClause);
}
// Do we have a composite select expression to process?
IQueryPlanNode rightComposite = null;
if (expression.NextComposite != null) {
TableSelectExpression compositeExpr = expression.NextComposite;
// Generate the TableExpressionFromSet hierarchy for the expression,
TableExpressionFromSet compositeFromSet = GenerateFromSet(compositeExpr, db);
// Form the right plan
rightComposite = FormQueryPlan(db, compositeExpr, compositeFromSet, null);
}
// Do we do a final subset column?
ObjectName[] aliases = null;
if (doSubsetColumn) {
// Make up the lists
ObjectName[] subsetVars = new ObjectName[sz];
aliases = new ObjectName[sz];
for (int i = 0; i < sz; ++i) {
SelectColumn scol = selectColumns[i];
subsetVars[i] = scol.InternalName.Clone();
aliases[i] = scol.Alias.Clone();
}
// If we are distinct then add the DistinctNode here
if (expression.Distinct)
node = new DistinctNode(node, subsetVars);
// Process the ORDER BY?
// Note that the ORDER BY has to occur before the subset call, but
// after the distinct because distinct can affect the ordering of the
// result.
if (rightComposite == null && orderBy != null)
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
// Rename the columns as specified in the SELECT
node = new SubsetNode(node, subsetVars, aliases);
} else {
// Process the ORDER BY?
if (rightComposite == null && orderBy != null)
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
}
// Do we have a composite to merge in?
if (rightComposite != null) {
// For the composite
node = new CompositeNode(node, rightComposite,
expression.CompositeFunction, expression.IsCompositeAll);
// Final order by?
if (orderBy != null) {
node = PlanForOrderBy(node, orderBy, fromSet, selectColumns);
}
// Ensure a final subset node
if (!(node is SubsetNode) && aliases != null) {
node = new SubsetNode(node, aliases, aliases);
}
}
return node;
}
