DRILL-1328: Support table statistics - Part 2

Add support for avg row-width and major type statistics.
Parallelize the ANALYZE implementation and stats UDF implementation to improve stats collection performance.
Update/fix rowcount, selectivity and ndv computations to improve plan costing.
Add options for configuring collection/usage of statistics.
Add new APIs and implementation for stats writer (as a precursor to Drill Metastore APIs).
Fix several stats/costing related issues identified while running TPC-H nad TPC-DS queries.
Add support for CPU sampling and nested scalar columns.
Add more testcases for collection and usage of statistics and fix remaining unit/functional test failures.

Thanks to Venki Korukanti (@vkorukanti) for the description below (modified to account for new changes). He graciously agreed to rebase the patch to latest master, fixed few issues and added few tests.

FUNCS: Statistics functions as UDFs:
Separate
Currently using FieldReader to ensure consistent output type so that Unpivot doesn't get confused. All stats columns should be Nullable, so that stats functions can return NULL when N/A.
* custom versions of "count" that always return BigInt
* HyperLogLog based NDV that returns BigInt that works only on VarChars
* HyperLogLog with binary output that only works on VarChars

OPS: Updated protobufs for new ops

OPS: Implemented StatisticsMerge

OPS: Implemented StatisticsUnpivot

ANALYZE: AnalyzeTable functionality
* JavaCC syntax more-or-less copied from LucidDB.
* (Basic) AnalyzePrule: DrillAnalyzeRel -> UnpivotPrel StatsMergePrel FilterPrel(for sampling) StatsAggPrel ScanPrel

ANALYZE: Add getMetadataTable() to AbstractSchema

USAGE: Change field access in QueryWrapper

USAGE: Add getDrillTable() to DrillScanRelBase and ScanPrel
* since ScanPrel does not inherit from DrillScanRelBase, this requires adding a DrillTable to the constructor
* This is done so that a custom ReflectiveRelMetadataProvider can access the DrillTable associated with Logical/Physical scans.

USAGE: Attach DrillStatsTable to DrillTable.
* DrillStatsTable represents the data scanned from a corresponding ".stats.drill" table
* In order to avoid doing query execution right after the ".stats.drill" table is found, metadata is not actually collected until the MaterializationVisitor is used.
** Currently, the metadata source must be a string (so that a SQL query can be created). Doing this with a table is probably more complicated.
** Query is set up to extract only the most recent statistics results for each column.

closes #729

1 files changed, 38 insertions, 0 deletions

diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/statistics/StatisticsMergeBatchCreator.java b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/statistics/StatisticsMergeBatchCreator.java
new file mode 100644
index 000000000..7599ab0d9
--- /dev/null
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/statistics/StatisticsMergeBatchCreator.java
@@ -0,0 +1,38 @@
+/*
+ * 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.drill.exec.physical.impl.statistics;
+
+import java.util.List;
+import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.exec.ops.ExecutorFragmentContext;
+import org.apache.drill.exec.physical.config.StatisticsMerge;
+import org.apache.drill.exec.physical.impl.BatchCreator;
+import org.apache.drill.exec.record.CloseableRecordBatch;
+import org.apache.drill.exec.record.RecordBatch;
+import org.apache.drill.shaded.guava.com.google.common.base.Preconditions;
+
+@SuppressWarnings("unused")
+public class StatisticsMergeBatchCreator implements BatchCreator<StatisticsMerge>{
+
+  @Override
+  public CloseableRecordBatch getBatch(ExecutorFragmentContext context, StatisticsMerge config,
+                                       List<RecordBatch> children) throws ExecutionSetupException {
+    Preconditions.checkArgument(children.size() == 1);
+    return new StatisticsMergeBatch(config, children.iterator().next(), context);
+  }
+}