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https://issues.apache.org/jira/browse/HIVE-22893?focusedWorklogId=393067&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-393067
]
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_r384201501
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java
##########
@@ -1590,6 +1610,43 @@ public static ColStatistics
getColStatisticsFromExpression(HiveConf conf, Statis
return colStats;
}
+ private static ColStatistics buildColStatForConstant(HiveConf conf, long
numRows, ExprNodeConstantDesc encd) {
+
+ long numNulls = 0;
+ long countDistincts = 0;
+ if (encd.getValue() == null) {
+ // null projection
+ numNulls = numRows;
+ } else {
+ countDistincts = 1;
+ }
+ String colType = encd.getTypeString();
+ colType = colType.toLowerCase();
+ ObjectInspector oi = encd.getWritableObjectInspector();
+ double avgColSize = getAvgColLenOf(conf, oi, colType);
+ ColStatistics colStats = new ColStatistics(encd.getName(), colType);
+ colStats.setAvgColLen(avgColSize);
+ colStats.setCountDistint(countDistincts);
+ colStats.setNumNulls(numNulls);
+
+ Optional<Long> value = getLongConstValue(encd);
Review comment:
What about other types? Can we either add them in this patch, or add a
comment and create a follow-up?
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Issue Time Tracking
-------------------
Worklog Id: (was: 393067)
> 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: 20m
> 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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