[CALCITE-7529] Casts between literals and TIME/TIMESTAMP can lose precision beyond milliseconds

core/src/main/java/org/apache/calcite/adapter/enumerable/RexToLixTranslator.java

@@ -477,7 +477,8 @@ private Expression getConvertExpression(
 
       case TIME:
         return RexImpTable.optimize2(operand, Expressions.isConstantNull(format)
-            ? Expressions.call(BuiltInMethod.UNIX_TIME_TO_STRING.method, operand)
+            ? Expressions.call(BuiltInMethod.UNIX_TIME_TO_STRING_WITH_PRECISION.method,
+                operand, Expressions.constant(sourceType.getPrecision()))
             : Expressions.call(
                 Expressions.new_(
                     BuiltInMethod.FORMAT_TIME.method.getDeclaringClass()),
@@ -494,7 +495,8 @@ private Expression getConvertExpression(
 
       case TIMESTAMP:
         return RexImpTable.optimize2(operand, Expressions.isConstantNull(format)
-            ? Expressions.call(BuiltInMethod.UNIX_TIMESTAMP_TO_STRING.method, operand)
+            ? Expressions.call(BuiltInMethod.UNIX_TIMESTAMP_TO_STRING_WITH_PRECISION.method,
+                operand, Expressions.constant(sourceType.getPrecision()))
             : Expressions.call(
                 Expressions.new_(
                     BuiltInMethod.FORMAT_TIMESTAMP.method.getDeclaringClass()),

core/src/main/java/org/apache/calcite/rex/RexBuilder.java

@@ -29,17 +29,21 @@
 import org.apache.calcite.rel.type.RelDataTypeSystemImpl;
 import org.apache.calcite.runtime.FlatLists;
 import org.apache.calcite.runtime.SqlFunctions;
+import org.apache.calcite.sql.SqlAbstractDateTimeLiteral;
 import org.apache.calcite.sql.SqlAggFunction;
 import org.apache.calcite.sql.SqlCollation;
 import org.apache.calcite.sql.SqlIntervalQualifier;
 import org.apache.calcite.sql.SqlKind;
 import org.apache.calcite.sql.SqlOperator;
 import org.apache.calcite.sql.SqlSpecialOperator;
+import org.apache.calcite.sql.SqlTimeLiteral;
+import org.apache.calcite.sql.SqlTimestampLiteral;
 import org.apache.calcite.sql.SqlUtil;
 import org.apache.calcite.sql.fun.SqlCountAggFunction;
 import org.apache.calcite.sql.fun.SqlLibraryOperators;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.sql.parser.SqlParserPos;
+import org.apache.calcite.sql.parser.SqlParserUtil;
 import org.apache.calcite.sql.type.ArraySqlType;
 import org.apache.calcite.sql.type.IntervalSqlType;
 import org.apache.calcite.sql.type.MapSqlType;
@@ -805,6 +809,12 @@ public RexNode makeCast(
           && SqlTypeUtil.isExactNumeric(type)) {
         return makeCastBooleanToExact(type, exp);
       }
+      final RexNode literalCast =
+          makeCastForTemporalLiteral(
+              pos, type, literal, matchNullability, safe, format);
+      if (literalCast != null) {
+        return literalCast;
+      }
       if (canRemoveCastFromLiteral(type, value, typeName)) {
         switch (typeName) {
         case INTERVAL_YEAR:
@@ -877,6 +887,123 @@ public RexNode makeCast(
     return makeAbstractCast(pos, type, exp, safe, format);
   }
 
+  private @Nullable RexNode makeCastForTemporalLiteral(
+      SqlParserPos pos,
+      RelDataType type,
+      RexLiteral literal,
+      boolean matchNullability,
+      boolean safe,
+      RexLiteral format) {
+    if (!format.isNull()) {
+      return null;
+    }
+    if (SqlTypeUtil.isCharacter(literal.getType())) {
+      return makeCastFromCharacterLiteralToTemporal(
+          pos, type, literal, matchNullability, safe, format);
+    }
+    if (SqlTypeUtil.isCharacter(type)) {
+      return makeCharacterLiteralFromTemporalLiteral(type, literal);
+    }
+    return null;
+  }
+
+  private @Nullable RexNode makeCastFromCharacterLiteralToTemporal(
+      SqlParserPos pos,
+      RelDataType type,
+      RexLiteral literal,
+      boolean matchNullability,
+      boolean safe,
+      RexLiteral format) {
+    final NlsString nlsString = literal.getValueAs(NlsString.class);
+    if (nlsString == null) {
+      return null;
+    }
+    final String value = nlsString.getValue().trim();
+    final RexNode temporalLiteral;
+    try {
+      switch (type.getSqlTypeName()) {
+      case TIME:
+        final SqlTimeLiteral timeLiteral =
+            SqlParserUtil.parseTimeLiteral(value, pos);
+        if (!isExactFractionalSecondLiteral(timeLiteral, value)) {
+          return null;
+        }
+        final TimeString time =
+            requireNonNull(timeLiteral.getValueAs(TimeString.class),
+                "timeLiteral.getValueAs(TimeString.class)");
+        temporalLiteral = makeTimeLiteral(time, type.getPrecision());
+        break;
+      case TIMESTAMP:
+        final SqlTimestampLiteral timestampLiteral =
+            SqlParserUtil.parseTimestampLiteral(value, pos);
+        if (!isExactFractionalSecondLiteral(timestampLiteral, value)) {
+          return null;
+        }
+        final TimestampString timestamp =
+            requireNonNull(timestampLiteral.getValueAs(TimestampString.class),
+                "timestampLiteral.getValueAs(TimestampString.class)");
+        temporalLiteral = makeTimestampLiteral(timestamp, type.getPrecision());
+        break;
+      default:
+        return null;
+      }
+    } catch (RuntimeException e) {
+      return safe ? makeNullLiteral(type) : null;
+    }
+    if (type.isNullable()
+        && !temporalLiteral.getType().isNullable()
+        && matchNullability) {
+      return makeAbstractCast(pos, type, temporalLiteral, safe, format);
+    }
+    return temporalLiteral;
+  }
+
+  /** Converts a TIME or TIMESTAMP literal to a character literal.
+   *
+   * <p>Returns null if the literal is not a TIME or TIMESTAMP, the literal
+   * cannot be read as the corresponding temporal string value, or the formatted
+   * temporal value does not fit in the target character type. */
+  private @Nullable RexNode makeCharacterLiteralFromTemporalLiteral(
+      RelDataType type,
+      RexLiteral literal) {
+    // Format temporal literals directly so they do not go through generated
+    // code, whose TIME/TIMESTAMP runtime values have millisecond precision.
+    final String value;
+    final int precision = literal.getType().getPrecision();
+    switch (literal.getType().getSqlTypeName()) {
+    case TIME:
+      final TimeString time = literal.getValueAs(TimeString.class);
+      if (time == null) {
+        return null;
+      }
+      value = time.toString(precision);
+      break;
+    case TIMESTAMP:
+      final TimestampString timestamp = literal.getValueAs(TimestampString.class);
+      if (timestamp == null) {
+        return null;
+      }
+      value = timestamp.toString(precision);
+      break;
+    default:
+      return null;
+    }
+    // Only create a character literal if the formatted temporal value fits in
+    // the target type.
+    return SqlTypeUtil.comparePrecision(type.getPrecision(), value.length()) >= 0
+        ? makeLiteral(value, type, true)
+        : null;
+  }
+
+  /** Returns whether a parsed TIME or TIMESTAMP literal has fractional-second
+   * precision high enough to preserve the original character value exactly. */
+  private static boolean isExactFractionalSecondLiteral(
+      SqlAbstractDateTimeLiteral literal, String value) {
+    return literal.getPrec() != 0
+        && literal.getPrec() != RelDataType.PRECISION_NOT_SPECIFIED
+        && literal.toFormattedString().equals(value);
+  }
+
   /** Returns the lowest granularity unit for the given unit.
    * YEAR and MONTH intervals are stored as months;
    * HOUR, MINUTE, SECOND intervals are stored as milliseconds. */

core/src/main/java/org/apache/calcite/rex/RexExecutorImpl.java

@@ -43,6 +43,7 @@
 
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Type;
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -136,14 +137,34 @@ public static RexExecutable getExecutable(RexBuilder rexBuilder, List<RexNode> e
   @Override public void reduce(RexBuilder rexBuilder, List<RexNode> constExps,
       List<RexNode> reducedValues) {
     assert reducedValues.isEmpty();
+    final List<RexNode> exps = new ArrayList<>();
+    final List<Integer> ordinals = new ArrayList<>();
+    for (int i = 0; i < constExps.size(); i++) {
+      final RexNode constExp = constExps.get(i);
+      // Literals are already reduced. Keep them as Rex values instead of
+      // round-tripping through generated code.
+      if (!(constExp instanceof RexLiteral)) {
+        ordinals.add(i);
+        exps.add(constExp);
+      }
+    }
+    if (exps.isEmpty()) {
+      reducedValues.addAll(constExps);
+      return;
+    }
     try {
-      String code = compile(rexBuilder, constExps, (list, index, storageType) -> {
+      String code = compile(rexBuilder, exps, (list, index, storageType) -> {
         throw new UnsupportedOperationException();
       });
 
-      final RexExecutable executable = new RexExecutable(code, constExps);
+      final RexExecutable executable = new RexExecutable(code, exps);
       executable.setDataContext(dataContext);
-      executable.reduce(rexBuilder, constExps, reducedValues);
+      final List<RexNode> values = new ArrayList<>(exps.size());
+      executable.reduce(rexBuilder, exps, values);
+      reducedValues.addAll(constExps);
+      for (int i = 0; i < ordinals.size(); i++) {
+        reducedValues.set(ordinals.get(i), values.get(i));
+      }
     } catch (RuntimeException ex) {
       // Something went wrong during constant reduction (for example,
       // we may have attempted a division by zero).

core/src/main/java/org/apache/calcite/util/BuiltInMethod.java

@@ -779,8 +779,12 @@ public enum BuiltInMethod {
       String.class, int.class),
   UNIX_DATE_TO_STRING(DateTimeUtils.class, "unixDateToString", int.class),
   UNIX_TIME_TO_STRING(DateTimeUtils.class, "unixTimeToString", int.class),
+  UNIX_TIME_TO_STRING_WITH_PRECISION(DateTimeUtils.class, "unixTimeToString",
+      int.class, int.class),
   UNIX_TIMESTAMP_TO_STRING(DateTimeUtils.class, "unixTimestampToString",
       long.class),
+  UNIX_TIMESTAMP_TO_STRING_WITH_PRECISION(DateTimeUtils.class,
+      "unixTimestampToString", long.class, int.class),
   INTERVAL_YEAR_MONTH_TO_STRING(DateTimeUtils.class,
       "intervalYearMonthToString", int.class, TimeUnitRange.class),
   INTERVAL_DAY_TIME_TO_STRING(DateTimeUtils.class, "intervalDayTimeToString",