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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-1328) Support table statistics
Date Wed, 18 May 2016 23:17:13 GMT

    [ https://issues.apache.org/jira/browse/DRILL-1328?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15290065#comment-15290065
] 

ASF GitHub Bot commented on DRILL-1328:
---------------------------------------

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

    https://github.com/apache/drill/pull/425#discussion_r63799694
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/AnalyzePrule.java
---
    @@ -0,0 +1,64 @@
    +/**
    + * 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
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    + * 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.planner.physical;
    +
    +import com.google.common.collect.ImmutableList;
    +import com.google.common.collect.Lists;
    +import org.apache.calcite.plan.RelOptRule;
    +import org.apache.calcite.plan.RelOptRuleCall;
    +import org.apache.calcite.plan.RelTraitSet;
    +import org.apache.calcite.rel.RelNode;
    +import org.apache.calcite.rel.SingleRel;
    +import org.apache.drill.exec.planner.common.DrillStatsTable;
    +import org.apache.drill.exec.planner.logical.DrillAnalyzeRel;
    +import org.apache.drill.exec.planner.logical.DrillRel;
    +import org.apache.drill.exec.planner.logical.RelOptHelper;
    +
    +import java.util.List;
    +
    +public class AnalyzePrule extends Prule {
    +  public static final RelOptRule INSTANCE = new AnalyzePrule();
    +
    +  private static final List<String> FUNCTIONS = ImmutableList.of(
    +      "statcount", // total number of entries in the table
    --- End diff --
    
    These constants are hardcoded in multiple places, might be hard to track.


> Support table statistics
> ------------------------
>
>                 Key: DRILL-1328
>                 URL: https://issues.apache.org/jira/browse/DRILL-1328
>             Project: Apache Drill
>          Issue Type: Improvement
>            Reporter: Cliff Buchanan
>             Fix For: Future
>
>         Attachments: 0001-PRE-Set-value-count-in-splitAndTransfer.patch
>
>
> This consists of several subtasks
> * implement operators to generate statistics
> * add "analyze table" support to parser/planner
> * create a metadata provider to allow statistics to be used by optiq in planning optimization
> * implement statistics functions
> Right now, the bulk of this functionality is implemented, but it hasn't been rigorously
tested and needs to have some definite answers for some of the parts "around the edges" (how
analyze table figures out where the table statistics are located, how a table "append" should
work in a read only file system)
> Also, here are a few known caveats:
> * table statistics are collected by creating a sql query based on the string path of
the table. This should probably be done with a Table reference.
> * Case sensitivity for column statistics is probably iffy
> * Math for combining two column NDVs into a joint NDV should be checked.
> * Schema changes aren't really being considered yet.
> * adding getDrillTable is probably unnecessary; it might be better to do getTable().unwrap(DrillTable.class)



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