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https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=393070&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393070
]
ASF GitHub Bot logged work on HIVE-22893:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Feb/20 00:09
Start Date: 26/Feb/20 00:09
Worklog Time Spent: 10m
Work Description: jcamachor commented on pull request #915: HIVE-22893
StatEstimate
URL: https://github.com/apache/hive/pull/915#discussion_r384197923
##########
File path: common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
##########
@@ -2519,6 +2519,9 @@ private static void
populateLlapDaemonVarsSet(Set<String> llapDaemonVarsSetLocal
"higher compute cost. (NDV means the number of distinct
values.). It only affects the FM-Sketch \n" +
"(not the HLL algorithm which is the default), where it
computes the number of necessary\n" +
" bitvectors to achieve the accuracy."),
+ HIVE_STATS_USE_UDF_ESTIMATORS("hive.stats.use.statestimators", true,
+ "Statestimators are able to provide more accurate column statistic
infos for UDF results."),
Review comment:
Statestimators -> Estimators
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Issue Time Tracking
-------------------
Worklog Id: (was: 393070)
Time Spent: 0.5h (was: 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
>
> Time Spent: 0.5h
> 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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