/// <summary>
/// Check if the expression is minimal: does not have a subselect, aggregation and does not need view resources
/// </summary>
/// <param name="expression">to inspect</param>
/// <returns>null if minimal, otherwise name of offending sub-expression</returns>
public static string IsMinimalExpression(ExprNode expression)
{
ExprNodeSubselectDeclaredDotVisitor subselectVisitor = new ExprNodeSubselectDeclaredDotVisitor();
expression.Accept(subselectVisitor);
if (subselectVisitor.Subselects.Count > 0) {
return "a subselect";
}
ExprNodeViewResourceVisitor viewResourceVisitor = new ExprNodeViewResourceVisitor();
expression.Accept(viewResourceVisitor);
if (viewResourceVisitor.ExprNodes.Count > 0) {
return "a function that requires view resources (prior, prev)";
}
IList<ExprAggregateNode> aggregateNodes = new List<ExprAggregateNode>();
ExprAggregateNodeUtil.GetAggregatesBottomUp(expression, aggregateNodes);
if (!aggregateNodes.IsEmpty()) {
return "an aggregation function";
}
return null;
}
public static StatementSpecCompiled Compile(
StatementSpecRaw spec,
Compilable compilable,
bool isSubquery,
bool isOnDemandQuery,
Attribute[] annotations,
IList<ExprSubselectNode> subselectNodes,
IList<ExprTableAccessNode> tableAccessNodes,
StatementRawInfo statementRawInfo,
StatementCompileTimeServices compileTimeServices)
{
IList<StreamSpecCompiled> compiledStreams;
ISet<string> eventTypeReferences = new HashSet<string>();
if (!isOnDemandQuery && spec.FireAndForgetSpec != null) {
throw new StatementSpecCompileException(
"Provided EPL expression is an on-demand query expression (not a continuous query)",
compilable.ToEPL());
}
// If not using a join and not specifying a data window, make the where-clause, if present, the filter of the stream
// if selecting using filter spec, and not subquery in where clause
if (spec.StreamSpecs.Count == 1 &&
spec.StreamSpecs[0] is FilterStreamSpecRaw &&
spec.StreamSpecs[0].ViewSpecs.Length == 0 &&
spec.WhereClause != null &&
spec.OnTriggerDesc == null &&
!isSubquery &&
!isOnDemandQuery &&
(tableAccessNodes == null || tableAccessNodes.IsEmpty())) {
bool disqualified;
ExprNode whereClause = spec.WhereClause;
var visitorX = new ExprNodeSubselectDeclaredDotVisitor();
whereClause.Accept(visitorX);
disqualified = visitorX.Subselects.Count > 0 ||
HintEnum.DISABLE_WHEREEXPR_MOVETO_FILTER.GetHint(annotations) != null;
if (!disqualified) {
var viewResourceVisitor = new ExprNodeViewResourceVisitor();
whereClause.Accept(viewResourceVisitor);
disqualified = viewResourceVisitor.ExprNodes.Count > 0;
}
if (!disqualified) {
spec.WhereClause = null;
var streamSpec = (FilterStreamSpecRaw) spec.StreamSpecs[0];
streamSpec.RawFilterSpec.FilterExpressions.Add(whereClause);
}
}
// compile select-clause
var selectClauseCompiled = CompileSelectClause(spec.SelectClauseSpec);
// Determine subselects in filter streams, these may need special handling for locking
var visitor = new ExprNodeSubselectDeclaredDotVisitor();
try {
StatementSpecRawWalkerSubselectAndDeclaredDot.WalkStreamSpecs(spec, visitor);
}
catch (ExprValidationException ex) {
throw new StatementSpecCompileException(ex.Message, ex, compilable.ToEPL());
}
foreach (var subselectNode in visitor.Subselects) {
subselectNode.IsFilterStreamSubselect = true;
}
// Determine subselects for compilation, and lambda-expression shortcut syntax for named windows
visitor.Reset();
GroupByClauseExpressions groupByRollupExpressions;
try {
StatementSpecRawWalkerSubselectAndDeclaredDot.WalkSubselectAndDeclaredDotExpr(spec, visitor);
var expressionCopier = new ExpressionCopier(
spec,
statementRawInfo.OptionalContextDescriptor,
compileTimeServices,
visitor);
groupByRollupExpressions = GroupByExpressionHelper.GetGroupByRollupExpressions(
spec.GroupByExpressions,
spec.SelectClauseSpec,
spec.HavingClause,
spec.OrderByList,
expressionCopier);
}
catch (ExprValidationException ex) {
throw new StatementSpecCompileException(ex.Message, ex, compilable.ToEPL());
}
if (isSubquery && !visitor.Subselects.IsEmpty()) {
throw new StatementSpecCompileException(
"Invalid nested subquery, subquery-within-subquery is not supported",
compilable.ToEPL());
}
if (isOnDemandQuery && !visitor.Subselects.IsEmpty()) {
throw new StatementSpecCompileException(
"Subqueries are not a supported feature of on-demand queries",
compilable.ToEPL());
}
foreach (var subselectNode in visitor.Subselects) {
if (!subselectNodes.Contains(subselectNode)) {
subselectNodes.Add(subselectNode);
}
}
// Compile subselects found
var subselectNumber = 0;
foreach (var subselect in subselectNodes) {
StatementSpecRaw raw = subselect.StatementSpecRaw;
var compiled = Compile(
raw,
compilable,
true,
isOnDemandQuery,
annotations,
Collections.GetEmptyList<ExprSubselectNode>(),
Collections.GetEmptyList<ExprTableAccessNode>(),
statementRawInfo,
compileTimeServices);
subselect.SetStatementSpecCompiled(compiled, subselectNumber);
subselectNumber++;
}
// Set table-access number
var tableAccessNumber = 0;
foreach (var tableAccess in tableAccessNodes) {
tableAccess.TableAccessNumber = tableAccessNumber;
tableAccessNumber++;
}
// compile each stream used
try {
compiledStreams = new List<StreamSpecCompiled>(spec.StreamSpecs.Count);
var streamNum = 0;
foreach (var rawSpec in spec.StreamSpecs) {
streamNum++;
var compiled = StreamSpecCompiler.Compile(
rawSpec,
eventTypeReferences,
spec.InsertIntoDesc != null,
spec.StreamSpecs.Count > 1,
false,
spec.OnTriggerDesc != null,
rawSpec.OptionalStreamName,
streamNum,
statementRawInfo,
compileTimeServices);
compiledStreams.Add(compiled);
}
}
catch (ExprValidationException ex) {
if (ex.Message == null) {
throw new StatementSpecCompileException(
"Unexpected exception compiling statement, please consult the log file and report the exception",
ex,
compilable.ToEPL());
}
throw new StatementSpecCompileException(ex.Message, ex, compilable.ToEPL());
}
catch (EPException ex) {
throw new StatementSpecCompileException(ex.Message, ex, compilable.ToEPL());
}
catch (Exception ex) {
var text = "Unexpected error compiling statement";
Log.Error(text, ex);
throw new StatementSpecCompileException(
text + ": " + ex.GetType().Name + ":" + ex.Message,
ex,
compilable.ToEPL());
}
return new StatementSpecCompiled(
spec,
compiledStreams.ToArray(),
selectClauseCompiled,
annotations,
groupByRollupExpressions,
subselectNodes,
visitor.DeclaredExpressions,
tableAccessNodes);
}
