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https://issues.apache.org/jira/browse/HIVE-21924?focusedWorklogId=319444&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-319444
 ]

ASF GitHub Bot logged work on HIVE-21924:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 27/Sep/19 09:17
            Start Date: 27/Sep/19 09:17
    Worklog Time Spent: 10m 
      Work Description: sankarh commented on pull request #791: HIVE-21924
URL: https://github.com/apache/hive/pull/791#discussion_r328983856
 
 

 ##########
 File path: 
ql/src/test/queries/clientpositive/file_with_header_footer_aggregation.q
 ##########
 @@ -0,0 +1,94 @@
+set hive.mapred.mode=nonstrict;
+
+dfs ${system:test.dfs.mkdir} ${system:test.tmp.dir};
+dfs -copyFromLocal ../../data/files/header_footer_table_4  
${system:test.tmp.dir}/header_footer_table_4;
+
+CREATE TABLE numbrs (numbr int);
+INSERT INTO numbrs VALUES (1), (2), (3), (4), (5), (6), (7), (8), (9), (10), 
(11), (12), (NULL);
+CREATE EXTERNAL TABLE header_footer_table_4 (header_int int, header_name 
string, header_choice varchar(10)) ROW FORMAT DELIMITED FIELDS TERMINATED BY 
',' LOCATION '${system:test.tmp.dir}/header_footer_table_4' tblproperties 
("skip.header.line.count"="1", "skip.footer.line.count"="2");
+
+SELECT * FROM header_footer_table_4;
+
+SELECT * FROM header_footer_table_4 ORDER BY header_int LIMIT 8;
+
+-- should return nothing as title is correctly skipped
+SELECT * FROM header_footer_table_4 WHERE header_choice = 'header_choice';
 
 Review comment:
   Also, test count(*) as well.
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 319444)
    Time Spent: 1h 20m  (was: 1h 10m)

> Split text files even if header/footer exists
> ---------------------------------------------
>
>                 Key: HIVE-21924
>                 URL: https://issues.apache.org/jira/browse/HIVE-21924
>             Project: Hive
>          Issue Type: Improvement
>          Components: File Formats
>    Affects Versions: 2.4.0, 4.0.0, 3.2.0
>            Reporter: Prasanth Jayachandran
>            Assignee: Mustafa Iman
>            Priority: Major
>              Labels: pull-request-available
>         Attachments: HIVE-21924.patch
>
>          Time Spent: 1h 20m
>  Remaining Estimate: 0h
>
> https://github.com/apache/hive/blob/967a1cc98beede8e6568ce750ebeb6e0d048b8ea/ql/src/java/org/apache/hadoop/hive/ql/io/HiveInputFormat.java#L494-L503
>  
> {code}
>     int headerCount = 0;
>     int footerCount = 0;
>     if (table != null) {
>       headerCount = Utilities.getHeaderCount(table);
>       footerCount = Utilities.getFooterCount(table, conf);
>       if (headerCount != 0 || footerCount != 0) {
>         // Input file has header or footer, cannot be splitted.
>         HiveConf.setLongVar(conf, ConfVars.MAPREDMINSPLITSIZE, 
> Long.MAX_VALUE);
>       }
>     }
> {code}
> this piece of code makes the CSV (or any text files with header/footer) files 
> not splittable if header or footer is present. 
> If only header is present, we can find the offset after first line break and 
> use that to split. Similarly for footer, may be read few KB's of data at the 
> end and find the last line break offset. Use that to determine the data range 
> which can be used for splitting. Few reads during split generation are 
> cheaper than not splitting the file at all.  



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