Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/637#discussion_r86489899
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/stat/ParquetPredicates.java
---
@@ -0,0 +1,334 @@
+/**
+ * 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
+ * <p/>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p/>
+ * 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.drill.exec.expr.stat;
+
+import org.apache.drill.common.expression.BooleanOperator;
+import org.apache.drill.common.expression.ExpressionPosition;
+import org.apache.drill.common.expression.LogicalExpression;
+import org.apache.drill.common.expression.LogicalExpressionBase;
+import org.apache.drill.common.expression.visitors.ExprVisitor;
+import org.apache.parquet.column.statistics.Statistics;
+import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+public abstract class ParquetPredicates {
+ public static abstract class ParquetCompPredicate extends
LogicalExpressionBase implements ParquetFilterPredicate {
+ protected final LogicalExpression left;
+ protected final LogicalExpression right;
+
+ public ParquetCompPredicate(LogicalExpression left, LogicalExpression
right) {
+ super(left.getPosition());
+ this.left = left;
+ this.right = right;
+ }
+
+ @Override
+ public Iterator<LogicalExpression> iterator() {
+ final List<LogicalExpression> args = new ArrayList<>();
+ args.add(left);
+ args.add(right);
+ return args.iterator();
+ }
+
+ @Override
+ public <T, V, E extends Exception> T accept(ExprVisitor<T, V, E>
visitor, V value) throws E {
+ return visitor.visitUnknown(this, value);
+ }
+
+ }
+
+ public static abstract class ParquetBooleanPredicate extends
BooleanOperator implements ParquetFilterPredicate {
+ public ParquetBooleanPredicate(String name, List<LogicalExpression>
args, ExpressionPosition pos) {
+ super(name, args, pos);
+ }
+
+ @Override
+ public <T, V, E extends Exception> T accept(ExprVisitor<T, V, E>
visitor, V value) throws E {
+ return visitor.visitBooleanOperator(this, value);
+ }
+ }
+
+ public static class AndPredicate extends ParquetBooleanPredicate {
+ public AndPredicate(String name, List<LogicalExpression> args,
ExpressionPosition pos) {
+ super(name, args, pos);
+ }
+
+ @Override
+ public boolean canDrop(RangeExprEvaluator evaluator) {
+ // "and" : as long as one branch is OK to drop, we can drop it.
+ for (LogicalExpression child : this) {
+ if (((ParquetFilterPredicate) child).canDrop(evaluator)) {
+ return true;
+ }
+ }
+ return false;
+ }
+ }
+
+ public static class OrPredicate extends ParquetBooleanPredicate {
+ public OrPredicate(String name, List<LogicalExpression> args,
ExpressionPosition pos) {
+ super(name, args, pos);
+ }
+
+ @Override
+ public boolean canDrop(RangeExprEvaluator evaluator) {
+ for (LogicalExpression child : this) {
+ // "long" : as long as one branch is NOT ok to drop, we can NOT
drop it.
+ if (! ((ParquetFilterPredicate) child).canDrop(evaluator)) {
+ return false;
+ }
+ }
+
+ return true;
+ }
+ }
+
+ // is this column chunk composed entirely of nulls?
+ // assumes the column chunk's statistics is not empty
+ protected static boolean isAllNulls(Statistics stat, long rowCount) {
+ return stat.getNumNulls() == rowCount;
+ }
+
+ // are there any nulls in this column chunk?
+ // assumes the column chunk's statistics is not empty
+ protected static boolean hasNulls(Statistics stat) {
+ return stat.getNumNulls() > 0;
+ }
+
+ /**
+ * EQ (=) predicate
+ */
+ public static class EqualPredicate extends ParquetCompPredicate {
+ public EqualPredicate(LogicalExpression left, LogicalExpression right)
{
+ super(left, right);
+ }
+
+ @Override
+ public boolean canDrop(RangeExprEvaluator evaluator) {
--- End diff --
Add comments to explain the main differences:
1. expressions in filter predicate, including CAST expression.
2. requirements of ColumnChunkMetaData
3. column compare constant_value vs expression_of_column compare
expression_of_column.
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