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https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=393328&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393328
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ASF GitHub Bot logged work on HIVE-22893:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 26/Feb/20 10:11
Start Date: 26/Feb/20 10:11
Worklog Time Spent: 10m
Work Description: kgyrtkirk commented on pull request #915: HIVE-22893
StatEstimate
URL: https://github.com/apache/hive/pull/915#discussion_r384336187
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java
##########
@@ -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:
There are interfaces which are prefixed with "I" and also there are some
which do not not have it...
We don't have convention for this... but naturally, I think that prefixing
interfaces with "I" and abstract classes with "Abstract" is helpfull.
What I see is that interfaces which are not prefixed with "I" are described
that they "are" interfaces in the apidoc...I think that the "I" in the name
makes it clear for both the reader and writer whats the topic here; and by that
it facilitates it's documentation to contain more naturally what are the
contracts of it.
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Issue Time Tracking
-------------------
Worklog Id: (was: 393328)
Time Spent: 1h 10m (was: 1h)
> 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: 1h 10m
> 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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