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From paul-rogers <...@git.apache.org>
Subject [GitHub] drill pull request #729: Drill 1328: Support table statistics for Parquet
Date Sat, 11 Feb 2017 21:57:15 GMT
Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/729#discussion_r100677171
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/statistics/StatisticsAggBatch.java
---
    @@ -0,0 +1,256 @@
    +/**
    + * 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.physical.impl.statistics;
    +
    +import com.google.common.collect.Lists;
    +import com.sun.codemodel.JExpr;
    +import org.apache.drill.common.expression.ErrorCollector;
    +import org.apache.drill.common.expression.ErrorCollectorImpl;
    +import org.apache.drill.common.expression.FunctionCallFactory;
    +import org.apache.drill.common.expression.LogicalExpression;
    +import org.apache.drill.common.expression.SchemaPath;
    +import org.apache.drill.common.expression.ValueExpressions;
    +import org.apache.drill.exec.exception.ClassTransformationException;
    +import org.apache.drill.exec.exception.OutOfMemoryException;
    +import org.apache.drill.exec.exception.SchemaChangeException;
    +import org.apache.drill.exec.expr.ClassGenerator;
    +import org.apache.drill.exec.expr.CodeGenerator;
    +import org.apache.drill.exec.expr.ExpressionTreeMaterializer;
    +import org.apache.drill.exec.expr.TypeHelper;
    +import org.apache.drill.exec.expr.ValueVectorWriteExpression;
    +import org.apache.drill.exec.ops.FragmentContext;
    +import org.apache.drill.exec.physical.config.StatisticsAggregate;
    +import org.apache.drill.exec.physical.impl.aggregate.StreamingAggBatch;
    +import org.apache.drill.exec.physical.impl.aggregate.StreamingAggTemplate;
    +import org.apache.drill.exec.physical.impl.aggregate.StreamingAggregator;
    +import org.apache.drill.exec.planner.physical.StatsAggPrel.OperatorPhase;
    +import org.apache.drill.exec.record.BatchSchema.SelectionVectorMode;
    +import org.apache.drill.exec.record.MaterializedField;
    +import org.apache.drill.exec.record.RecordBatch;
    +import org.apache.drill.exec.record.TypedFieldId;
    +import org.apache.drill.exec.store.ImplicitColumnExplorer;
    +import org.apache.drill.exec.vector.ValueVector;
    +import org.apache.drill.exec.vector.complex.FieldIdUtil;
    +import org.apache.drill.exec.vector.complex.MapVector;
    +
    +import java.io.IOException;
    +import java.util.GregorianCalendar;
    +import java.util.List;
    +import java.util.TimeZone;
    +
    +/**
    + * TODO: This needs cleanup. Currently the key values are constants and we compare the
constants
    + * for every record. Seems unnecessary.
    + *
    + * Example input and output:
    + * Schema of incoming batch: region_id (VARCHAR), sales_city (VARCHAR), cnt (BIGINT)
    + * Schema of output:
    + *    "schema" : BIGINT - Schema number. For each schema change this number is incremented.
    + *    "computed" : BIGINT - What time is it computed?
    + *    "columns"       : MAP - Column names
    + *       "region_id"  : VARCHAR
    + *       "sales_city" : VARCHAR
    + *       "cnt"        : VARCHAR
    + *    "statscount" : MAP
    + *       "region_id"  : BIGINT - statscount(region_id) - aggregation over all values
of region_id
    + *                      in incoming batch
    + *       "sales_city" : BIGINT - statscount(sales_city)
    + *       "cnt"        : BIGINT - statscount(cnt)
    + *    "nonnullstatcount" : MAP
    + *       "region_id"  : BIGINT - nonnullstatcount(region_id)
    + *       "sales_city" : BIGINT - nonnullstatcount(sales_city)
    + *       "cnt"        : BIGINT - nonnullstatcount(cnt)
    + *   .... another map for next stats function ....
    + */
    +public class StatisticsAggBatch extends StreamingAggBatch {
    +  private List<String> functions;
    +  private int schema = 0;
    +
    +  public StatisticsAggBatch(StatisticsAggregate popConfig, RecordBatch incoming,
    +      FragmentContext context) throws OutOfMemoryException {
    +    super(popConfig, incoming, context);
    +    this.functions = popConfig.getFunctions();
    +  }
    +
    +  private void createKeyColumn(String name, LogicalExpression expr, List<LogicalExpression>
keyExprs,
    +      List<TypedFieldId> keyOutputIds) throws SchemaChangeException {
    +    ErrorCollector collector = new ErrorCollectorImpl();
    +
    +    LogicalExpression mle = ExpressionTreeMaterializer.materialize(expr, incoming, collector,
    +        context.getFunctionRegistry());
    +
    +    MaterializedField outputField = MaterializedField.create(name, mle.getMajorType());
    +    ValueVector vector = TypeHelper.getNewVector(outputField, oContext.getAllocator());
    +
    +    keyExprs.add(mle);
    +    keyOutputIds.add(container.add(vector));
    +
    +    if (collector.hasErrors()) {
    --- End diff --
    
    Shouldn't this check be done just after the call to materialize? Else, we are proceeding
along doing work in an error state, only later abandoning the work just done with an exception...
    
    Also, we seem to discard the actual errors. Perhaps rethrow the first error? Or, find
an exception class that can hold onto a list of exceptions? Just rethrowing the fist is probably
fine, most people will fix just the first error and retry.


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