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https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=393741&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393741
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ASF GitHub Bot logged work on HIVE-22893:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Feb/20 20:52
Start Date: 26/Feb/20 20:52
Worklog Time Spent: 10m
Work Description: jcamachor commented on pull request #915: HIVE-22893
StatEstimate
URL: https://github.com/apache/hive/pull/915#discussion_r384758044
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File path: ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java
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@@ -73,6 +74,9 @@
import org.apache.hadoop.hive.ql.plan.Statistics;
import org.apache.hadoop.hive.ql.plan.Statistics.State;
import org.apache.hadoop.hive.ql.stats.BasicStats.Factory;
+import org.apache.hadoop.hive.ql.stats.estimator.IStatEstimator;
Review comment:
Sounds good.
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Issue Time Tracking
-------------------
Worklog Id: (was: 393741)
Time Spent: 1.5h (was: 1h 20m)
> Enhance data size estimation for fields computed by UDFs
> --------------------------------------------------------
>
> Key: HIVE-22893
> URL: https://issues.apache.org/jira/browse/HIVE-22893
> Project: Hive
> Issue Type: Improvement
> Components: Statistics
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22893.01.patch, HIVE-22893.02.patch,
> HIVE-22893.03.patch, HIVE-22893.04.patch, HIVE-22893.05.patch,
> HIVE-22893.06.patch, HIVE-22893.07.patch, HIVE-22893.08.patch,
> HIVE-22893.09.patch, HIVE-22893.10.patch, HIVE-22893.11.patch,
> HIVE-22893.12.patch, HIVE-22893.13.patch
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> Right now if we have columnstat on a column ; we use that to estimate things
> about the column; - however if an UDF is executed on a column ; the resulting
> column is treated as unknown thing and defaults are assumed.
> An improvement could be to give wide estimation(s) in case of frequently used
> udf.
> For example; consider {{substr(c,1,1)}} ; no matter what the input; the
> output is at most a 1 long string
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