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https://issues.apache.org/jira/browse/HIVE-23530?focusedWorklogId=437836&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-437836
]
ASF GitHub Bot logged work on HIVE-23530:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 27/May/20 15:06
Start Date: 27/May/20 15:06
Worklog Time Spent: 10m
Work Description: jcamachor commented on a change in pull request #1034:
URL: https://github.com/apache/hive/pull/1034#discussion_r431213790
##########
File path: ql/src/java/org/apache/hadoop/hive/ql/stats/ColStatsProcessor.java
##########
@@ -127,15 +131,16 @@ public int process(Hive db, Table tbl) throws Exception {
LOG.debug("Because {} is infinite or NaN, we skip stats.",
columnName, e);
}
}
+ pos += columnStatsFields.size();
Review comment:
Changed the method to use iterators.
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Issue Time Tracking
-------------------
Worklog Id: (was: 437836)
Time Spent: 1h 20m (was: 1h 10m)
> Use SQL functions instead of compute_stats UDAF to compute column statistics
> ----------------------------------------------------------------------------
>
> Key: HIVE-23530
> URL: https://issues.apache.org/jira/browse/HIVE-23530
> Project: Hive
> Issue Type: Improvement
> Components: Statistics
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-23530.01.patch, HIVE-23530.02.patch,
> HIVE-23530.03.patch, HIVE-23530.patch
>
> Time Spent: 1h 20m
> Remaining Estimate: 0h
>
> Currently we compute column statistics by relying on the {{compute_stats}}
> UDAF. For instance, for a given table {{tbl}}, the query to compute
> statistics for columns is translated internally into:
> {code}
> SELECT compute_stats(c1),
> compute_stats(c2),
> ...
> FROM tbl;
> {code}
> {{compute_stats}} produces data for the stats available for each column type,
> e.g., struct<"max":long,"min":long,"countnulls":long,...>.
> This issue is to produce a query that relies purely on SQL functions instead:
> {code}
> SELECT max(c1), min(c1), count(case when c1 is null then 1 else null end),
> ...
> FROM tbl;
> {code}
> This will allow us to deprecate the {{compute_stats}} UDAF since it mostly
> duplicates functionality found in those other functions. Additionally, many
> of those functions already provide a vectorized implementation so the
> approach can potentially improve the performance of column stats collection.
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