/
Expr.java
1929 lines (1763 loc) · 70.7 KB
/
Expr.java
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package org.apache.impala.analysis;
import static org.apache.impala.analysis.ToSqlOptions.DEFAULT;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import org.apache.impala.analysis.BinaryPredicate.Operator;
import org.apache.impala.catalog.BuiltinsDb;
import org.apache.impala.catalog.Function;
import org.apache.impala.catalog.Function.CompareMode;
import org.apache.impala.catalog.PrimitiveType;
import org.apache.impala.catalog.ScalarType;
import org.apache.impala.catalog.Type;
import org.apache.impala.common.AnalysisException;
import org.apache.impala.common.InternalException;
import org.apache.impala.common.SqlCastException;
import org.apache.impala.common.TreeNode;
import org.apache.impala.rewrite.ExprRewriter;
import org.apache.impala.service.FeSupport;
import org.apache.impala.thrift.TColumnValue;
import org.apache.impala.thrift.TExplainLevel;
import org.apache.impala.thrift.TExpr;
import org.apache.impala.thrift.TExprNode;
import org.apache.impala.thrift.TFunction;
import org.apache.impala.util.MathUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Joiner;
import com.google.common.base.MoreObjects;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicates;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
/**
* Root of the expr node hierarchy.
*/
abstract public class Expr extends TreeNode<Expr> implements ParseNode, Cloneable {
private static final Logger LOG = LoggerFactory.getLogger(Expr.class);
// Limits on the number of expr children and the depth of an expr tree. These maximum
// values guard against crashes due to stack overflows (IMPALA-432) and were
// experimentally determined to be safe.
public static final int EXPR_CHILDREN_LIMIT = 10000;
// The expr depth limit is mostly due to our recursive implementation of clone().
public static final int EXPR_DEPTH_LIMIT = 1000;
// Name of the function that needs to be implemented by every Expr that
// supports negation.
private static final String NEGATE_FN = "negate";
// To be used where we cannot come up with a better estimate (selectivity_ is -1).
public static final double DEFAULT_SELECTIVITY = 0.1;
// The relative costs of different Exprs. These numbers are not intended as a precise
// reflection of running times, but as simple heuristics for ordering Exprs from cheap
// to expensive.
// TODO(tmwarshall): Get these costs in a more principled way, eg. with a benchmark.
public static final float ARITHMETIC_OP_COST = 1;
public static final float BINARY_PREDICATE_COST = 1;
public static final float VAR_LEN_BINARY_PREDICATE_COST = 5;
public static final float COMPOUND_PREDICATE_COST = 1;
public static final float FUNCTION_CALL_COST = 10;
public static final float IS_NOT_EMPTY_COST = 1;
public static final float IS_NULL_COST = 1;
public static final float LIKE_COST = 10;
public static final float LITERAL_COST = 1;
public static final float SLOT_REF_COST = 1;
public static final float TIMESTAMP_ARITHMETIC_COST = 5;
public static final float UNKNOWN_COST = -1;
// Arbitrary max exprs considered for constant propagation due to O(n^2) complexity.
private static final int CONST_PROPAGATION_EXPR_LIMIT = 200;
// To be used when estimating the cost of Exprs of type string where we don't otherwise
// have an estimate of how long the strings produced by that Expr are.
public static final int DEFAULT_AVG_STRING_LENGTH = 5;
// returns true if an Expr is a non-analytic aggregate.
public static final com.google.common.base.Predicate<Expr> IS_AGGREGATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).isAggregateFunction();
}
};
// Returns true if an Expr is a NOT CompoundPredicate.
public static final com.google.common.base.Predicate<Expr> IS_NOT_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof CompoundPredicate &&
((CompoundPredicate)arg).getOp() == CompoundPredicate.Operator.NOT;
}
};
// Returns true if an Expr is an OR CompoundPredicate.
public static final com.google.common.base.Predicate<Expr> IS_OR_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof CompoundPredicate &&
((CompoundPredicate)arg).getOp() == CompoundPredicate.Operator.OR;
}
};
// Returns true if an Expr is a scalar subquery
public static final com.google.common.base.Predicate<Expr> IS_SCALAR_SUBQUERY =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg.isScalarSubquery();
}
};
// Returns true if an Expr has a subquery as a direct child.
public static final com.google.common.base.Predicate<Expr> HAS_SUBQUERY_CHILD =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
for (Expr child : arg.getChildren()) {
if (child instanceof Subquery) return true;
}
return false;
}
};
// Returns true if an Expr is an aggregate function that returns non-null on
// an empty set (e.g. count).
public static final com.google.common.base.Predicate<Expr>
NON_NULL_EMPTY_AGG = new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).returnsNonNullOnEmpty();
}
};
// Returns true if an Expr is a builtin aggregate function.
public static final com.google.common.base.Predicate<Expr> IS_BUILTIN_AGG_FN =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr &&
((FunctionCallExpr)arg).getFnName().isBuiltin();
}
};
// Returns true if an Expr is a user-defined aggregate function.
public static final com.google.common.base.Predicate<Expr> IS_UDA_FN =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return IS_AGGREGATE.apply(arg) &&
!((FunctionCallExpr)arg).getFnName().isBuiltin();
}
};
public static final com.google.common.base.Predicate<Expr> IS_TRUE_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BoolLiteral && ((BoolLiteral)arg).getValue();
}
};
public static final com.google.common.base.Predicate<Expr> IS_FALSE_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BoolLiteral && !((BoolLiteral)arg).getValue();
}
};
public static final com.google.common.base.Predicate<Expr> IS_EQ_BINARY_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) { return BinaryPredicate.getEqSlots(arg) != null; }
};
public static final com.google.common.base.Predicate<Expr> IS_NOT_EQ_BINARY_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BinaryPredicate
&& ((BinaryPredicate) arg).getOp() != Operator.EQ
&& ((BinaryPredicate) arg).getOp() != Operator.NOT_DISTINCT;
}
};
public static final com.google.common.base.Predicate<Expr> IS_BINARY_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) { return arg instanceof BinaryPredicate; }
};
public static final com.google.common.base.Predicate<Expr>
IS_EXPR_EQ_LITERAL_PREDICATE = new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BinaryPredicate
&& ((BinaryPredicate) arg).getOp() == Operator.EQ
&& IS_LITERAL.apply(((BinaryPredicate) arg).getChild(1));
}
};
public static final com.google.common.base.Predicate<Expr>
IS_NONDETERMINISTIC_BUILTIN_FN_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr
&& ((FunctionCallExpr) arg).isNondeterministicBuiltinFn();
}
};
public static final com.google.common.base.Predicate<Expr> IS_UDF_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr
&& !((FunctionCallExpr) arg).getFnName().isBuiltin();
}
};
/**
* @return true if the expression is a literal.
*/
public static final com.google.common.base.Predicate<Expr> IS_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof LiteralExpr;
}
};
/**
* @return true if the expression is a null literal.
*/
public static final com.google.common.base.Predicate<Expr> IS_NULL_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof NullLiteral;
}
};
/**
* @return true if the expression is a literal value other than NULL.
*/
public static final com.google.common.base.Predicate<Expr> IS_NON_NULL_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return IS_LITERAL.apply(arg) && !IS_NULL_LITERAL.apply(arg);
}
};
/**
* @return true if the expression is a null literal, or a
* cast of a null (as created by the ConstantFoldingRule.)
*/
public static final com.google.common.base.Predicate<Expr> IS_NULL_VALUE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
if (arg instanceof NullLiteral) return true;
if (! (arg instanceof CastExpr)) return false;
return IS_NULL_VALUE.apply(((CastExpr) arg).getChild(0));
}
};
/**
* @return true if the expression is a literal, or a
* cast of a null (as created by the ConstantFoldingRule.)
*/
public static final com.google.common.base.Predicate<Expr> IS_LITERAL_VALUE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return IS_LITERAL.apply(arg) || IS_NULL_VALUE.apply(arg);
}
};
public static final com.google.common.base.Predicate<Expr> IS_INT_LITERAL =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return IS_LITERAL.apply(arg) && arg.getType().isIntegerType();
}
};
public static final com.google.common.base.Predicate<Expr>
IS_CONDITIONAL_BUILTIN_FN_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr
&& ((FunctionCallExpr) arg).isConditionalBuiltinFn();
}
};
public static final com.google.common.base.Predicate<Expr> IS_IS_NULL_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof IsNullPredicate
&& !((IsNullPredicate) arg).isNotNull();
}
};
public static final com.google.common.base.Predicate<Expr>
IS_DISTINCT_FROM_OR_NOT_DISTINCT_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof BinaryPredicate
&& (((BinaryPredicate) arg).getOp() == Operator.DISTINCT_FROM
|| ((BinaryPredicate) arg).getOp() == Operator.NOT_DISTINCT);
}
};
public static final com.google.common.base.Predicate<Expr> IS_CASE_EXPR_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof CaseExpr;
}
};
public static final com.google.common.base.Predicate<Expr> IS_ALWAYS_TRUE_PREDICATE =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof Predicate
&& ((Predicate) arg).hasAlwaysTrueHint();
}
};
// Returns true if an Expr is a builtin sleep function.
public static final com.google.common.base.Predicate<Expr> IS_FN_SLEEP =
new com.google.common.base.Predicate<Expr>() {
@Override
public boolean apply(Expr arg) {
return arg instanceof FunctionCallExpr
&& ((FunctionCallExpr) arg).getFnName().isBuiltin()
&& ((FunctionCallExpr) arg).getFnName().getFunction() != null
&& ((FunctionCallExpr) arg).getFnName().getFunction().equals("sleep");
}
};
// id that's unique across the entire query statement and is assigned by
// Analyzer.registerConjuncts(); only assigned for the top-level terms of a
// conjunction, and therefore null for most Exprs
protected ExprId id_;
// true if Expr is an auxiliary predicate that was generated by the plan generation
// process to facilitate predicate propagation;
// false if Expr originated with a query stmt directly
private boolean isAuxExpr_ = false;
protected Type type_; // result of analysis
protected boolean isOnClauseConjunct_; // set by analyzer
// Flag to indicate whether to wrap this expr's toSql() in parenthesis. Set by parser.
// Needed for properly capturing expr precedences in the SQL string.
protected boolean printSqlInParens_ = false;
// Estimated probability of a predicate evaluating to true. Set during analysis.
// Between 0 and 1, or set to -1 if the selectivity could not be estimated.
protected double selectivity_;
// Estimated relative cost of evaluating this expression, including the costs of
// its children. Set during analysis and used to sort conjuncts within a PlanNode.
// Has a default value of -1 indicating unknown cost if the cost of this expression
// or any of its children was not set, but it is required to be set for any
// expression which may be part of a conjunct.
protected float evalCost_;
// estimated number of distinct values produced by Expr; invalid: -1
// set during analysis
protected long numDistinctValues_;
// Cached value of IsConstant(), set during analyze() and valid if isAnalyzed_ is true.
private boolean isConstant_;
// The function to call. This can either be a scalar or aggregate function.
// Set in analyze().
protected Function fn_;
// True after analysis successfully completed. Protected by accessors isAnalyzed() and
// analysisDone().
private boolean isAnalyzed_ = false;
// True if this has already been counted towards the number of statement expressions
private boolean isCountedForNumStmtExprs_ = false;
// For exprs of type Predicate, this keeps track of predicate hints
protected List<PlanHint> predicateHints_;
// Is codegen disabled for this expression ?
private boolean isCodegenDisabled_ = false;
protected Expr() {
type_ = Type.INVALID;
selectivity_ = -1.0;
evalCost_ = -1.0f;
numDistinctValues_ = -1;
}
/**
* Copy c'tor used in clone().
*/
protected Expr(Expr other) {
id_ = other.id_;
isAuxExpr_ = other.isAuxExpr_;
type_ = other.type_;
isAnalyzed_ = other.isAnalyzed_;
isOnClauseConjunct_ = other.isOnClauseConjunct_;
printSqlInParens_ = other.printSqlInParens_;
selectivity_ = other.selectivity_;
evalCost_ = other.evalCost_;
numDistinctValues_ = other.numDistinctValues_;
isConstant_ = other.isConstant_;
fn_ = other.fn_;
isCountedForNumStmtExprs_ = other.isCountedForNumStmtExprs_;
children_ = Expr.cloneList(other.children_);
if (other.predicateHints_ != null) {
predicateHints_ = new ArrayList<>();
predicateHints_.addAll(other.predicateHints_);
}
isCodegenDisabled_ = other.isCodegenDisabled_;
}
public boolean isAnalyzed() { return isAnalyzed_; }
public ExprId getId() { return id_; }
protected void setId(ExprId id) { id_ = id; }
public Type getType() { return type_; }
public double getSelectivity() { return selectivity_; }
public boolean hasSelectivity() { return selectivity_ >= 0; }
public float getCost() {
Preconditions.checkState(isAnalyzed_);
return evalCost_;
}
public boolean hasCost() { return evalCost_ >= 0; }
public long getNumDistinctValues() { return numDistinctValues_; }
public boolean getPrintSqlInParens() { return printSqlInParens_; }
public void setPrintSqlInParens(boolean b) { printSqlInParens_ = b; }
public boolean isOnClauseConjunct() { return isOnClauseConjunct_; }
public void setIsOnClauseConjunct(boolean b) { isOnClauseConjunct_ = b; }
public boolean isAuxExpr() { return isAuxExpr_; }
public void setIsAuxExpr() { isAuxExpr_ = true; }
public Function getFn() { return fn_; }
public void disableCodegen() {
isCodegenDisabled_ = true;
for (Expr child : children_) {
child.disableCodegen();
}
}
/**
* Perform semantic analysis of node and all of its children.
* Throws exception if any errors found.
* @see ParseNode#analyze(Analyzer)
*/
// TODO: Analyze for expressions should return a possibly-rewritten
// expression, leaving the StmtNode version to analyze statements
// in-place.
public final void analyze(Analyzer analyzer) throws AnalysisException {
if (isAnalyzed()) return;
// Check the expr child limit.
if (children_.size() > EXPR_CHILDREN_LIMIT) {
String sql = toSql();
String sqlSubstr = sql.substring(0, Math.min(80, sql.length()));
throw new AnalysisException(String.format("Exceeded the maximum number of child " +
"expressions (%s).\nExpression has %s children:\n%s...",
EXPR_CHILDREN_LIMIT, children_.size(), sqlSubstr));
}
// analyzer may be null for certain literal constructions (e.g. IntLiteral).
if (analyzer != null) {
analyzer.incrementCallDepth();
// Check the expr depth limit. Do not print the toSql() to not overflow the stack.
if (analyzer.getCallDepth() > EXPR_DEPTH_LIMIT) {
throw new AnalysisException(String.format("Exceeded the maximum depth of an " +
"expression tree (%s).", EXPR_DEPTH_LIMIT));
}
incrementNumStmtExprs(analyzer);
}
for (Expr child: children_) {
child.analyze(analyzer);
}
if (analyzer != null) analyzer.decrementCallDepth();
computeNumDistinctValues();
// Do all the analysis for the expr subclass before marking the Expr analyzed.
analyzeImpl(analyzer);
evalCost_ = computeEvalCost();
analysisDone();
}
protected void analyzeHints(Analyzer analyzer) throws AnalysisException {
if (predicateHints_ != null && !predicateHints_.isEmpty()) {
if (!(this instanceof Predicate)) {
throw new AnalysisException("Expr hints are only supported for predicates");
}
for (PlanHint hint : predicateHints_) {
if (hint.is("ALWAYS_TRUE")) {
((Predicate) this).setHasAlwaysTrueHint(true);
// If the top level expr has always_true hint, its conjuncts must
// also have the same hint (note that there's a TODO in the parser
// grammar to allow hints on a per expr basis).
List<Expr> conjuncts = getConjuncts();
if (conjuncts.size() > 1) {
for (Expr e : conjuncts) ((Predicate) e).setHasAlwaysTrueHint(true);
}
analyzer.setHasPlanHints();
} else {
analyzer.addWarning("Predicate hint not recognized: " + hint);
}
}
}
}
/**
* Does subclass-specific analysis. Subclasses should override analyzeImpl().
*/
abstract protected void analyzeImpl(Analyzer analyzer) throws AnalysisException;
/**
* Helper function to analyze this expr and assert that the analysis was successful.
* TODO: This function could be used in many more places to clean up. Consider
* adding an IAnalyzable interface or similar to and move this helper into Analyzer
* such that non-Expr things can use the helper also.
*/
public void analyzeNoThrow(Analyzer analyzer) {
try {
analyze(analyzer);
} catch (AnalysisException e) {
throw new IllegalStateException(e);
}
}
/**
* Helper function to properly count the number of statement expressions.
* If this expression has not been counted already and this is not a WITH clause,
* increment the number of statement expressions. This function guarantees that an
* expression will be counted at most once.
*/
private void incrementNumStmtExprs(Analyzer analyzer) {
// WITH clauses use a separate Analyzer with its own GlobalState. Skip counting
// this expression towards that GlobalState. If the view defined by the WITH
// clause is referenced, it will be counted during that analysis.
if (analyzer.hasWithClause()) return;
// If the expression is already counted, do not count it again. This is important
// for expressions that can be cloned (e.g. when doing Expr::trySubstitute()).
if (isCountedForNumStmtExprs_) return;
analyzer.incrementNumStmtExprs();
isCountedForNumStmtExprs_ = true;
}
/**
* Compute and return evalcost of this expr given the evalcost of all children has been
* computed. Should be called bottom-up whenever the structure of subtree is modified.
*/
abstract protected float computeEvalCost();
protected void computeNumDistinctValues() {
if (isConstant()) {
numDistinctValues_ = 1;
} else {
numDistinctValues_ = -1;
// get the max number of distinct values over all children of this node
for (Expr child: children_) {
// A constant should not override a -1 from a SlotRef, so we only consider
// non-constant expressions. This is functionally similar to considering
// only the SlotRefs, except that it allows an Expr to override the values
// that come out of its children.
if (!child.isConstant()) {
numDistinctValues_ = Math.max(numDistinctValues_, child.getNumDistinctValues());
}
}
}
}
/**
* Collects the returns types of the child nodes in an array.
*/
protected Type[] collectChildReturnTypes() {
Type[] childTypes = new Type[children_.size()];
for (int i = 0; i < children_.size(); ++i) {
childTypes[i] = children_.get(i).type_;
}
return childTypes;
}
/**
* Looks up in the catalog the builtin for 'name' and 'argTypes'.
* Returns null if the function is not found.
*/
protected Function getBuiltinFunction(Analyzer analyzer, String name,
Type[] argTypes, CompareMode mode) throws AnalysisException {
FunctionName fnName = new FunctionName(BuiltinsDb.NAME, name);
Function searchDesc = new Function(fnName, argTypes, Type.INVALID, false);
return analyzer.getCatalog().getFunction(searchDesc, mode);
}
/**
* Generates the necessary casts for the children of this expr to call fn_.
* child(0) is cast to the function's first argument, child(1) to the second etc.
*
* If ignoreWildcardDecimals is true, the function will not cast arguments that
* are wildcard decimals. This is used for builtins where the cast is done within
* the BE function.
* Otherwise, if the function signature contains wildcard decimals, each wildcard child
* argument will be cast to the highest resolution that can contain all of the child
* wildcard arguments.
* e.g. fn(decimal(*), decimal(*))
* called with fn(decimal(10,2), decimal(5,3))
* both children will be cast to (11, 3).
*
* If strictDecimal is true, we will only consider casts between decimal types that
* result in no loss of information. If it is not possible to come with such casts,
* we will throw an exception.
*/
protected void castForFunctionCall(
boolean ignoreWildcardDecimals, boolean strictDecimal) throws AnalysisException {
Preconditions.checkState(fn_ != null);
Type[] fnArgs = fn_.getArgs();
Type resolvedWildcardType = getResolvedWildCardType(strictDecimal);
if (resolvedWildcardType != null) {
if (resolvedWildcardType.isNull()) {
throw new SqlCastException(String.format(
"Cannot resolve DECIMAL precision and scale from NULL type in %s function.",
fn_.getFunctionName().getFunction()));
}
if (resolvedWildcardType.isInvalid() && !ignoreWildcardDecimals) {
StringBuilder argTypes = new StringBuilder();
for (int j = 0; j < children_.size(); ++j) {
if (argTypes.length() > 0) argTypes.append(", ");
Type childType = children_.get(j).type_;
argTypes.append(childType.toSql());
}
throw new SqlCastException(String.format(
"Cannot resolve DECIMAL types of the %s(%s) function arguments. You need " +
"to wrap the arguments in a CAST.", fn_.getFunctionName().getFunction(),
argTypes.toString()));
}
}
for (int i = 0; i < children_.size(); ++i) {
// For varargs, we must compare with the last type in fnArgs.argTypes.
int ix = Math.min(fnArgs.length - 1, i);
if (fnArgs[ix].isWildcardDecimal()) {
if (children_.get(i).type_.isDecimal() && ignoreWildcardDecimals) continue;
if (children_.get(i).type_.isDecimal() || !ignoreWildcardDecimals) {
Preconditions.checkState(resolvedWildcardType != null);
Preconditions.checkState(!resolvedWildcardType.isInvalid());
if (!children_.get(i).type_.equals(resolvedWildcardType)) {
castChild(resolvedWildcardType, i);
}
} else if (children_.get(i).type_.isNull()) {
castChild(ScalarType.createDecimalType(), i);
} else {
Preconditions.checkState(children_.get(i).type_.isScalarType());
// It is safe to assign an arbitrary decimal here only if the backend function
// can handle it (in which case ignoreWildcardDecimals is true).
Preconditions.checkState(ignoreWildcardDecimals);
castChild(((ScalarType) children_.get(i).type_).getMinResolutionDecimal(), i);
}
} else if (!children_.get(i).type_.matchesType(fnArgs[ix])) {
castChild(fnArgs[ix], i);
}
}
}
/**
* Returns the max resolution type of all the wild card decimal types.
* Returns null if there are no wild card types. If strictDecimal is enabled, will
* return an invalid type if it is not possible to come up with a decimal type that
* is guaranteed to not lose information.
*/
Type getResolvedWildCardType(boolean strictDecimal) {
Type result = null;
Type[] fnArgs = fn_.getArgs();
for (int i = 0; i < children_.size(); ++i) {
// For varargs, we must compare with the last type in fnArgs.argTypes.
int ix = Math.min(fnArgs.length - 1, i);
if (!fnArgs[ix].isWildcardDecimal()) continue;
Type childType = children_.get(i).type_;
Preconditions.checkState(!childType.isWildcardDecimal(),
"Child expr should have been resolved.");
Preconditions.checkState(childType.isScalarType(),
"Function should not have resolved with a non-scalar child type.");
if (result == null) {
ScalarType decimalType = (ScalarType) childType;
result = decimalType.getMinResolutionDecimal();
} else {
result = Type.getAssignmentCompatibleType(
result, childType, false, strictDecimal);
}
}
if (result != null && !result.isNull()) {
result = ((ScalarType)result).getMinResolutionDecimal();
Preconditions.checkState(result.isDecimal() || result.isInvalid());
Preconditions.checkState(!result.isWildcardDecimal());
}
return result;
}
/**
* Returns true if e is a CastExpr and the target type is a decimal.
*/
private boolean isExplicitCastToDecimal(Expr e) {
if (!(e instanceof CastExpr)) return false;
CastExpr c = (CastExpr)e;
return !c.isImplicit() && c.getType().isDecimal();
}
/**
* Returns a clone of child with all decimal-typed NumericLiterals in it explicitly
* cast to targetType.
*/
private Expr convertDecimalLiteralsToFloat(Analyzer analyzer, Expr child,
Type targetType) throws AnalysisException {
if (!targetType.isFloatingPointType() && !targetType.isIntegerType()) return child;
if (targetType.isIntegerType()) targetType = Type.DOUBLE;
List<NumericLiteral> literals = new ArrayList<>();
child.collectAll(Predicates.instanceOf(NumericLiteral.class), literals);
ExprSubstitutionMap smap = new ExprSubstitutionMap();
for (NumericLiteral l: literals) {
if (!l.getType().isDecimal()) continue;
NumericLiteral castLiteral = (NumericLiteral) l.clone();
castLiteral.explicitlyCastToFloat(targetType);
smap.put(l, castLiteral);
}
return child.substitute(smap, analyzer, false);
}
/**
* DECIMAL_V1:
* ----------
* This function applies a heuristic that casts literal child exprs of this expr from
* decimal to floating point in certain circumstances to reduce processing cost. In
* earlier versions of Impala's decimal support, it was much slower than floating point
* arithmetic. The original rationale for the automatic casting follows.
*
* Decimal has a higher processing cost than floating point and we should not pay
* the cost if the user does not require the accuracy. For example:
* "select float_col + 1.1" would start out with 1.1 as a decimal(2,1) and the
* float_col would be promoted to a high accuracy decimal. This function will identify
* this case and treat 1.1 as a float.
* In the case of "decimal_col + 1.1", 1.1 would remain a decimal.
* In the case of "float_col + cast(1.1 as decimal(2,1))", the result would be a
* decimal.
*
* Another way to think about it is that DecimalLiterals are analyzed as returning
* decimals (of the narrowest precision/scale) and we later convert them to a floating
* point type according to a heuristic that attempts to guess what the user intended.
*
* DECIMAL_V2:
* ----------
* This function does nothing. All decimal numeric literals are interpreted as decimals
* and the normal expression typing rules apply.
*/
protected void convertNumericLiteralsFromDecimal(Analyzer analyzer)
throws AnalysisException {
Preconditions.checkState(this instanceof ArithmeticExpr ||
this instanceof BinaryPredicate);
// This heuristic conversion is not part of DECIMAL_V2.
if (analyzer.getQueryOptions().isDecimal_v2()) return;
if (getChildCount() == 1) return; // Do not attempt to convert for unary ops
Preconditions.checkState(getChildCount() == 2);
Type t0 = getChild(0).getType();
Type t1 = getChild(1).getType();
boolean c0IsConstantDecimal = getChild(0).isConstant() && t0.isDecimal();
boolean c1IsConstantDecimal = getChild(1).isConstant() && t1.isDecimal();
if (c0IsConstantDecimal && c1IsConstantDecimal) return;
if (!c0IsConstantDecimal && !c1IsConstantDecimal) return;
// Only child(0) or child(1) is a const decimal. See if we can cast it to
// the type of the other child.
if (c0IsConstantDecimal && !isExplicitCastToDecimal(getChild(0))) {
Expr c0 = convertDecimalLiteralsToFloat(analyzer, getChild(0), t1);
setChild(0, c0);
}
if (c1IsConstantDecimal && !isExplicitCastToDecimal(getChild(1))) {
Expr c1 = convertDecimalLiteralsToFloat(analyzer, getChild(1), t0);
setChild(1, c1);
}
}
/**
* Helper function: analyze list of exprs
*/
public static void analyze(List<? extends Expr> exprs, Analyzer analyzer)
throws AnalysisException {
if (exprs == null) return;
for (Expr expr: exprs) {
expr.analyze(analyzer);
}
}
@Override
public final String toSql() {
return toSql(DEFAULT);
}
/**
* Some expression nodes are also statement-like and know about
* before/after rewrite expressions.
*/
@Override
public String toSql(ToSqlOptions options) {
return (printSqlInParens_) ? "(" + toSqlImpl(options) + ")" : toSqlImpl(options);
}
/**
* Returns a SQL string representing this expr. Subclasses should override this method
* instead of toSql() to ensure that parenthesis are properly added around the toSql().
*/
protected abstract String toSqlImpl(ToSqlOptions options);
protected String toSqlImpl() { return toSqlImpl(DEFAULT); };
// Convert this expr, including all children, to its Thrift representation.
public TExpr treeToThrift() {
if (type_.isNull()) {
// Hack to ensure BE never sees TYPE_NULL. If an expr makes it this far without
// being cast to a non-NULL type, the type doesn't matter and we can cast it
// arbitrarily.
Preconditions.checkState(IS_NULL_LITERAL.apply(this) ||
this instanceof SlotRef);
return NullLiteral.create(ScalarType.BOOLEAN).treeToThrift();
}
TExpr result = new TExpr();
treeToThriftHelper(result);
return result;
}
// Append a flattened version of this expr, including all children, to 'container'.
protected void treeToThriftHelper(TExpr container) {
Preconditions.checkState(isAnalyzed_,
"Must be analyzed before serializing to thrift. %s", this);
Preconditions.checkState(!type_.isWildcardDecimal());
// The BE should never see TYPE_NULL
Preconditions.checkState(!type_.isNull(), "Expr has type null!");
TExprNode msg = new TExprNode();
msg.type = type_.toThrift();
msg.is_constant = isConstant_;
msg.num_children = children_.size();
msg.setIs_codegen_disabled(isCodegenDisabled_);
if (fn_ != null) {
TFunction thriftFn = fn_.toThrift();
thriftFn.setLast_modified_time(fn_.getLastModifiedTime());
msg.setFn(thriftFn);
if (fn_.hasVarArgs()) msg.setVararg_start_idx(fn_.getNumArgs() - 1);
}
toThrift(msg);
container.addToNodes(msg);
for (Expr child: children_) {
child.treeToThriftHelper(container);
}
}
// Convert this expr into msg (excluding children), which requires setting
// msg.op as well as the expr-specific field.
protected abstract void toThrift(TExprNode msg);
/**
* Returns the product of the given exprs' number of distinct values or -1 if any of
* the exprs have an invalid number of distinct values. Uses saturating arithmetic,
* so that if the product would overflow, return Long.MAX_VALUE.
*/
public static long getNumDistinctValues(List<Expr> exprs) {
if (exprs == null || exprs.isEmpty()) return 0;
long numDistinctValues = 1;
for (Expr expr: exprs) {
if (expr.getNumDistinctValues() == -1) {
numDistinctValues = -1;
break;
}
numDistinctValues = MathUtil.saturatingMultiply(
numDistinctValues, expr.getNumDistinctValues());
}
return numDistinctValues;
}
public static List<TExpr> treesToThrift(List<? extends Expr> exprs) {
List<TExpr> result = new ArrayList<>();
for (Expr expr: exprs) {
result.add(expr.treeToThrift());
}
return result;
}
public boolean isAggregate() {
return IS_AGGREGATE.apply(this);
}
public List<String> childrenToSql(ToSqlOptions options) {
List<String> result = new ArrayList<>();
for (Expr child: children_) {
result.add(child.toSql(options));
}
return result;
}
public String debugString() {
return (id_ != null ? "exprid=" + id_.toString() + " " : "") + debugString(children_);
}
public static String debugString(List<? extends Expr> exprs) {
if (exprs == null || exprs.isEmpty()) return "";
List<String> strings = new ArrayList<>();
for (Expr expr: exprs) {
strings.add(expr.debugString());
}
return Joiner.on(" ").join(strings);
}
public static String toSql(List<? extends Expr> exprs, ToSqlOptions options) {
if (exprs == null || exprs.isEmpty()) return "";
List<String> strings = new ArrayList<>();
for (Expr expr: exprs) {
strings.add(expr.toSql(options));
}
return Joiner.on(", ").join(strings);
}
/**
* Returns true if this expr matches 'that'. Two exprs match if:
* 1. The tree structures ignoring implicit casts are the same.
* 2. For every pair of corresponding SlotRefs, slotRefCmp.matches() returns true.
* 3. For every pair of corresponding non-SlotRef exprs, localEquals() returns true.
*/
public boolean matches(Expr that, SlotRef.Comparator slotRefCmp) {
if (that == null) return false;
if (this instanceof CastExpr && ((CastExpr)this).isImplicit()) {
return children_.get(0).matches(that, slotRefCmp);
}
if (that instanceof CastExpr && ((CastExpr)that).isImplicit()) {
return matches(((CastExpr) that).children_.get(0), slotRefCmp);
}
if (this instanceof SlotRef && that instanceof SlotRef) {
return slotRefCmp.matches((SlotRef)this, (SlotRef)that);
}
if (!localEquals(that)) return false;
if (children_.size() != that.children_.size()) return false;
for (int i = 0; i < children_.size(); ++i) {
if (!children_.get(i).matches(that.children_.get(i), slotRefCmp)) return false;
}
return true;
}
/**
* Local eq comparator. Returns true if this expr is equal to 'that' ignoring children.
*/
protected boolean localEquals(Expr that) {
return getClass() == that.getClass() &&
(fn_ == null ? that.fn_ == null : fn_.equals(that.fn_));
}
/**
* Returns true if two expressions are equal. The equality comparison works on analyzed
* as well as unanalyzed exprs by ignoring implicit casts.
*/
@Override
public final boolean equals(Object obj) {
return obj instanceof Expr && matches((Expr) obj, SlotRef.SLOTREF_EQ_CMP);
}