/**
* Returns a tuple descriptor for the aggregation/analytic's intermediate or final result,
* depending on whether isOutputTuple is true or false. Also updates the appropriate substitution
* map, and creates and registers auxiliary equality predicates between the grouping slots and the
* grouping exprs.
*/
private TupleDescriptor createTupleDesc(Analyzer analyzer, boolean isOutputTuple) {
TupleDescriptor result =
analyzer
.getDescTbl()
.createTupleDescriptor(tupleDebugName() + (isOutputTuple ? "-out" : "-intermed"));
List<Expr> exprs =
Lists.newArrayListWithCapacity(groupingExprs_.size() + aggregateExprs_.size());
exprs.addAll(groupingExprs_);
exprs.addAll(aggregateExprs_);
int aggregateExprStartIndex = groupingExprs_.size();
for (int i = 0; i < exprs.size(); ++i) {
Expr expr = exprs.get(i);
SlotDescriptor slotDesc = analyzer.addSlotDescriptor(result);
slotDesc.setLabel(expr.toSql());
slotDesc.setStats(ColumnStats.fromExpr(expr));
Preconditions.checkState(expr.getType().isValid());
slotDesc.setType(expr.getType());
if (i < aggregateExprStartIndex) {
// register equivalence between grouping slot and grouping expr;
// do this only when the grouping expr isn't a constant, otherwise
// it'll simply show up as a gratuitous HAVING predicate
// (which would actually be incorrect if the constant happens to be NULL)
if (!expr.isConstant()) {
analyzer.createAuxEquivPredicate(new SlotRef(slotDesc), expr.clone());
}
} else {
Preconditions.checkArgument(expr instanceof FunctionCallExpr);
FunctionCallExpr aggExpr = (FunctionCallExpr) expr;
if (aggExpr.isMergeAggFn()) {
slotDesc.setLabel(aggExpr.getChild(0).toSql());
} else {
slotDesc.setLabel(aggExpr.toSql());
}
// count(*) is non-nullable.
if (aggExpr.getFnName().getFunction().equals("count")) {
// TODO: Consider making nullability a property of types or of builtin agg fns.
// row_number, rank, and dense_rank are non-nullable as well.
slotDesc.setIsNullable(false);
}
if (!isOutputTuple) {
Type intermediateType = ((AggregateFunction) aggExpr.fn_).getIntermediateType();
if (intermediateType != null) {
// Use the output type as intermediate if the function has a wildcard decimal.
if (!intermediateType.isWildcardDecimal()) {
slotDesc.setType(intermediateType);
} else {
Preconditions.checkState(expr.getType().isDecimal());
}
}
}
}
}
String prefix = (isOutputTuple ? "result " : "intermediate ");
LOG.trace(prefix + " tuple=" + result.debugString());
return result;
}
public CastExpr(Type targetType, Expr e, boolean isImplicit) {
super();
Preconditions.checkArgument(targetType.isValid());
this.targetType_ = targetType;
this.isImplicit_ = isImplicit;
Preconditions.checkNotNull(e);
if (isImplicit) {
// replace existing implicit casts
if (e instanceof CastExpr) {
CastExpr castExpr = (CastExpr) e;
if (castExpr.isImplicit()) e = castExpr.getChild(0);
}
children_.add(e);
// Implicit casts don't call analyze()
// TODO: this doesn't seem like the cleanest approach but there are places
// we generate these (e.g. table loading) where there is no analyzer object.
try {
analyze();
computeNumDistinctValues();
} catch (AnalysisException ex) {
Preconditions.checkState(false, "Implicit casts should never throw analysis exception.");
}
isAnalyzed_ = true;
} else {
children_.add(e);
}
}
/** Checks for type compatibility of column and expr. Returns compatible (possibly cast) expr. */
private Expr checkTypeCompatibility(Column column, Expr expr) throws AnalysisException {
// Check for compatible type, and add casts to the selectListExprs if necessary.
// We don't allow casting to a lower precision type.
Type colType = column.getType();
Type exprType = expr.getType();
// Trivially compatible.
if (colType.equals(exprType)) return expr;
Type compatibleType = Type.getAssignmentCompatibleType(colType, exprType);
// Incompatible types.
if (!compatibleType.isValid()) {
throw new AnalysisException(
String.format(
"Target table '%s' is incompatible with SELECT / PARTITION expressions.\n"
+ "Expression '%s' (type: %s) is not compatible with column '%s' (type: %s)",
targetTableName_, expr.toSql(), exprType, column.getName(), colType));
}
// Loss of precision when inserting into the table.
if (!compatibleType.equals(colType) && !compatibleType.isNull()) {
throw new AnalysisException(
String.format(
"Possible loss of precision for target table '%s'.\n"
+ "Expression '%s' (type: %s) would need to be cast to %s"
+ " for column '%s'",
targetTableName_, expr.toSql(), exprType, colType, column.getName()));
}
// Add a cast to the selectListExpr to the higher type.
return expr.castTo(compatibleType);
}
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj instanceof CastExpr) {
CastExpr other = (CastExpr) obj;
return isImplicit_ == other.isImplicit_
&& targetType_.equals(other.targetType_)
&& super.equals(obj);
}
// Ignore implicit casts when comparing expr trees.
if (isImplicit_) return getChild(0).equals(obj);
return false;
}
public static void initBuiltins(Db db) {
for (Type fromType : Type.getSupportedTypes()) {
if (fromType.isNull()) continue;
for (Type toType : Type.getSupportedTypes()) {
if (toType.isNull()) continue;
// Disable casting from string to boolean
if (fromType.isStringType() && toType.isBoolean()) continue;
// Disable casting from boolean/timestamp to decimal
if ((fromType.isBoolean() || fromType.isDateType()) && toType.isDecimal()) {
continue;
}
if (fromType.getPrimitiveType() == PrimitiveType.STRING
&& toType.getPrimitiveType() == PrimitiveType.CHAR) {
// Allow casting from String to Char(N)
String beSymbol = "impala::CastFunctions::CastToChar";
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(ScalarType.CHAR),
Lists.newArrayList((Type) ScalarType.STRING),
false,
ScalarType.CHAR,
beSymbol,
null,
null,
true));
continue;
}
if (fromType.getPrimitiveType() == PrimitiveType.CHAR
&& toType.getPrimitiveType() == PrimitiveType.CHAR) {
// Allow casting from CHAR(N) to Char(N)
String beSymbol = "impala::CastFunctions::CastToChar";
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(ScalarType.CHAR),
Lists.newArrayList((Type) ScalarType.createCharType(-1)),
false,
ScalarType.CHAR,
beSymbol,
null,
null,
true));
continue;
}
if (fromType.getPrimitiveType() == PrimitiveType.VARCHAR
&& toType.getPrimitiveType() == PrimitiveType.VARCHAR) {
// Allow casting from VARCHAR(N) to VARCHAR(M)
String beSymbol = "impala::CastFunctions::CastToStringVal";
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(ScalarType.VARCHAR),
Lists.newArrayList((Type) ScalarType.VARCHAR),
false,
ScalarType.VARCHAR,
beSymbol,
null,
null,
true));
continue;
}
if (fromType.getPrimitiveType() == PrimitiveType.VARCHAR
&& toType.getPrimitiveType() == PrimitiveType.CHAR) {
// Allow casting from VARCHAR(N) to CHAR(M)
String beSymbol = "impala::CastFunctions::CastToChar";
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(ScalarType.CHAR),
Lists.newArrayList((Type) ScalarType.VARCHAR),
false,
ScalarType.CHAR,
beSymbol,
null,
null,
true));
continue;
}
if (fromType.getPrimitiveType() == PrimitiveType.CHAR
&& toType.getPrimitiveType() == PrimitiveType.VARCHAR) {
// Allow casting from CHAR(N) to VARCHAR(M)
String beSymbol = "impala::CastFunctions::CastToStringVal";
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(ScalarType.VARCHAR),
Lists.newArrayList((Type) ScalarType.CHAR),
false,
ScalarType.VARCHAR,
beSymbol,
null,
null,
true));
continue;
}
// Disable no-op casts
if (fromType.equals(toType) && !fromType.isDecimal()) continue;
String beClass =
toType.isDecimal() || fromType.isDecimal() ? "DecimalOperators" : "CastFunctions";
String beSymbol = "impala::" + beClass + "::CastTo" + Function.getUdfType(toType);
db.addBuiltin(
ScalarFunction.createBuiltin(
getFnName(toType),
Lists.newArrayList(fromType),
false,
toType,
beSymbol,
null,
null,
true));
}
}
}
private static String getFnName(Type targetType) {
return "castTo" + targetType.getPrimitiveType().toString();
}
private void analyze() throws AnalysisException {
targetType_.analyze();
if (targetType_.isComplexType()) {
throw new AnalysisException("Unsupported cast to complex type: " + targetType_.toSql());
}
boolean readyForCharCast =
children_.get(0).getType().getPrimitiveType() == PrimitiveType.STRING
|| children_.get(0).getType().getPrimitiveType() == PrimitiveType.CHAR;
if (targetType_.getPrimitiveType() == PrimitiveType.CHAR && !readyForCharCast) {
// Back end functions only exist to cast string types to CHAR, there is not a cast
// for every type since it is redundant with STRING. Casts to go through 2 casts:
// (1) cast to string, to stringify the value
// (2) cast to CHAR, to truncate or pad with spaces
CastExpr tostring = new CastExpr(ScalarType.STRING, children_.get(0), true);
tostring.analyze();
children_.set(0, tostring);
}
if (children_.get(0) instanceof NumericLiteral && targetType_.isFloatingPointType()) {
// Special case casting a decimal literal to a floating point number. The
// decimal literal can be interpreted as either and we want to avoid casts
// since that can result in loss of accuracy.
((NumericLiteral) children_.get(0)).explicitlyCastToFloat(targetType_);
}
if (children_.get(0).getType().isNull()) {
// Make sure BE never sees TYPE_NULL
uncheckedCastChild(targetType_, 0);
}
// Ensure child has non-null type (even if it's a null literal). This is required
// for the UDF interface.
if (children_.get(0) instanceof NullLiteral) {
NullLiteral nullChild = (NullLiteral) (children_.get(0));
nullChild.uncheckedCastTo(targetType_);
}
Type childType = children_.get(0).type_;
Preconditions.checkState(!childType.isNull());
if (childType.equals(targetType_)) {
noOp_ = true;
type_ = targetType_;
return;
}
FunctionName fnName = new FunctionName(Catalog.BUILTINS_DB, getFnName(targetType_));
Type[] args = {childType};
Function searchDesc = new Function(fnName, args, Type.INVALID, false);
if (isImplicit_) {
fn_ = Catalog.getBuiltin(searchDesc, CompareMode.IS_SUPERTYPE_OF);
Preconditions.checkState(fn_ != null);
} else {
fn_ = Catalog.getBuiltin(searchDesc, CompareMode.IS_IDENTICAL);
if (fn_ == null) {
// allow for promotion from CHAR to STRING; only if no exact match is found
fn_ = Catalog.getBuiltin(searchDesc.promoteCharsToStrings(), CompareMode.IS_IDENTICAL);
}
}
if (fn_ == null) {
throw new AnalysisException(
"Invalid type cast of "
+ getChild(0).toSql()
+ " from "
+ childType
+ " to "
+ targetType_);
}
Preconditions.checkState(
targetType_.matchesType(fn_.getReturnType()), targetType_ + " != " + fn_.getReturnType());
type_ = targetType_;
}
@Override
public String toSqlImpl() {
if (isImplicit_) return getChild(0).toSql();
return "CAST(" + getChild(0).toSql() + " AS " + targetType_.toString() + ")";
}