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https://issues.apache.org/jira/browse/HIVE-22239?focusedWorklogId=324942&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-324942
]
ASF GitHub Bot logged work on HIVE-22239:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 08/Oct/19 08:47
Start Date: 08/Oct/19 08:47
Worklog Time Spent: 10m
Work Description: kgyrtkirk commented on pull request #787: HIVE-22239
URL: https://github.com/apache/hive/pull/787#discussion_r332352109
##########
File path: common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
##########
@@ -2537,6 +2537,11 @@ private static void
populateLlapDaemonVarsSet(Set<String> llapDaemonVarsSetLocal
"When estimating output rows for a join involving multiple columns,
the default behavior assumes" +
"the columns are independent. Setting this flag to true will cause the
estimator to assume" +
"the columns are correlated."),
+
HIVE_STATS_RANGE_SELECTIVITY_UNIFORM_DISTRIBUTION("hive.stats.filter.range.uniform",
true,
+ "When estimating output rows from a condition, if a range predicate is
applied over a column and the" +
+ "minimum and maximum values for that column are available, assume
uniform distribution of values" +
+ "accross that range and scales number of rows proportionally. If this
is set to false, default" +
+ "selectivity value is used."),
Review comment:
small thing: could you add spaces at the end; because right now it contains
words like "theminimum" and "valuesacross"
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Issue Time Tracking
-------------------
Worklog Id: (was: 324942)
Time Spent: 50m (was: 40m)
> Scale data size using column value ranges
> -----------------------------------------
>
> Key: HIVE-22239
> URL: https://issues.apache.org/jira/browse/HIVE-22239
> Project: Hive
> Issue Type: Improvement
> Components: Physical Optimizer
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22239.01.patch, HIVE-22239.02.patch,
> HIVE-22239.patch
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> Currently, min/max values for columns are only used to determine whether a
> certain range filter falls out of range and thus filters all rows or none at
> all. If it does not, we just use a heuristic that the condition will filter
> 1/3 of the input rows. Instead of using that heuristic, we can use another
> one that assumes that data will be uniformly distributed across that range,
> and calculate the selectivity for the condition accordingly.
> This patch also includes the propagation of min/max column values from
> statistics to the optimizer for timestamp type.
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