[GitHub] drill pull request: DRILL-1328: Support table statistics

[vkorukanti <gi...@git.apache.org>]

Github user vkorukanti commented on a diff in the pull request:

    https://github.com/apache/drill/pull/425#discussion_r63745018
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StatisticsAggrFunctions.java ---
    @@ -0,0 +1,295 @@
    +/*******************************************************************************
    + * 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.
    + ******************************************************************************/
    +
    +/*
    + * This class is automatically generated from AggrTypeFunctions2.tdd using FreeMarker.
    + */
    +
    +package org.apache.drill.exec.expr.fn.impl;
    +
    +import io.netty.buffer.DrillBuf;
    +import org.apache.drill.exec.expr.DrillAggFunc;
    +import org.apache.drill.exec.expr.DrillSimpleFunc;
    +import org.apache.drill.exec.expr.annotations.FunctionTemplate;
    +import org.apache.drill.exec.expr.annotations.FunctionTemplate.NullHandling;
    +import org.apache.drill.exec.expr.annotations.FunctionTemplate.FunctionScope;
    +import org.apache.drill.exec.expr.annotations.Output;
    +import org.apache.drill.exec.expr.annotations.Param;
    +import org.apache.drill.exec.expr.annotations.Workspace;
    +import org.apache.drill.exec.expr.holders.BigIntHolder;
    +import org.apache.drill.exec.expr.holders.NullableBigIntHolder;
    +import org.apache.drill.exec.expr.holders.NullableVarBinaryHolder;
    +import org.apache.drill.exec.expr.holders.ObjectHolder;
    +import org.apache.drill.exec.vector.complex.reader.FieldReader;
    +
    +import javax.inject.Inject;
    +
    +@SuppressWarnings("unused")
    +public class StatisticsAggrFunctions {
    +  static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(StatisticsAggrFunctions.class);
    +
    +  @FunctionTemplate(name = "statcount", scope = FunctionTemplate.FunctionScope.POINT_AGGREGATE)
    +  public static class StatCount implements DrillAggFunc {
    +    @Param
    +    FieldReader in;
    +    @Workspace
    +    BigIntHolder count;
    +    @Output
    +    NullableBigIntHolder out;
    +
    +    @Override
    +    public void setup() {
    +      count = new BigIntHolder();
    +    }
    +
    +    @Override
    +    public void add() {
    +      count.value++;
    +    }
    +
    +    @Override
    +    public void output() {
    +      out.isSet = 1;
    +      out.value = count.value;
    +    }
    +
    +    @Override
    +    public void reset() {
    +      count.value = 0;
    +    }
    +  }
    +
    +  @FunctionTemplate(name = "nonnullstatcount", scope = FunctionTemplate.FunctionScope.POINT_AGGREGATE)
    +  public static class NonNullStatCount implements DrillAggFunc {
    +    @Param
    +    FieldReader in;
    +    @Workspace
    +    BigIntHolder count;
    +    @Output
    +    NullableBigIntHolder out;
    +
    +    @Override
    +    public void setup() {
    +      count = new BigIntHolder();
    +    }
    +
    +    @Override
    +    public void add() {
    +      if (in.isSet()) {
    +        count.value++;
    +      }
    +    }
    +
    +    @Override
    +    public void output() {
    +      out.isSet = 1;
    +      out.value = count.value;
    +    }
    +
    +    @Override
    +    public void reset() {
    +      count.value = 0;
    +    }
    +  }
    +
    +  @FunctionTemplate(name = "hll", scope = FunctionTemplate.FunctionScope.POINT_AGGREGATE)
    +  public static class HllFieldReader implements DrillAggFunc {
    +    @Param
    +    FieldReader in;
    +    @Workspace
    +    ObjectHolder work;
    +    @Output
    +    NullableVarBinaryHolder out;
    +    @Inject
    +    DrillBuf buffer;
    +
    +    @Override
    +    public void setup() {
    +      work = new ObjectHolder();
    +      work.obj = new com.clearspring.analytics.stream.cardinality.HyperLogLog(10);
    +    }
    +
    +    @Override
    +    public void add() {
    +      if (work.obj != null) {
    +        com.clearspring.analytics.stream.cardinality.HyperLogLog hll =
    +            (com.clearspring.analytics.stream.cardinality.HyperLogLog) work.obj;
    +        int mode = in.getType().getMode().getNumber();
    +        int type = in.getType().getMinorType().getNumber();
    +
    +        switch (mode) {
    +          case org.apache.drill.common.types.TypeProtos.DataMode.OPTIONAL_VALUE:
    +            if (!in.isSet()) {
    +              hll.offer(null);
    +              break;
    +            }
    +            // fall through //
    +          case org.apache.drill.common.types.TypeProtos.DataMode.REQUIRED_VALUE:
    +            switch (type) {
    +              case org.apache.drill.common.types.TypeProtos.MinorType.VARCHAR_VALUE:
    +                hll.offer(in.readText().toString());
    +                break;
    +              default:
    +                work.obj = null;
    +            }
    +            break;
    +          default:
    +            work.obj = null;
    +        }
    +      }
    +    }
    +
    +    @Override
    +    public void output() {
    +      if (work.obj != null) {
    +        com.clearspring.analytics.stream.cardinality.HyperLogLog hll =
    +            (com.clearspring.analytics.stream.cardinality.HyperLogLog) work.obj;
    +
    +        try {
    +          byte[] ba = hll.getBytes();
    +          out.buffer = buffer.reallocIfNeeded(ba.length);
    +          out.start = 0;
    +          out.end = ba.length;
    +          out.buffer.setBytes(0, ba);
    +          out.isSet = 1;
    +        } catch (java.io.IOException e) {
    +          throw new org.apache.drill.common.exceptions.DrillRuntimeException("Failed to get HyperLogLog output", e);
    --- End diff --
    
    Currently we have no mechanism to handle exceptions in UDFs. We generally tried to avoid `try...catch` blocks in UDFs, but in this case we need a `try...catch` block because `HyperLogLog.getBytes()` throws a checked exception. Once [DRILL-3764] (https://issues.apache.org/jira/browse/DRILL-3764) is fixed, we can change this accordingly.


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