private static String getFnName(Type targetType) {
return "castTo" + targetType.getPrimitiveType().toString();
}
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 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_;
}