[HIVE-7853] Make OrcNewInputFormat return row number as a key

• Type: Bug
• Status: Patch Available
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.13.1
• Component/s: File Formats
• Labels: Orc

Environment

all

• Assignee: Navis Ryu
• Reporter: john
• Created: 22/Aug/14 19:19
• Updated: 20/Oct/14 09:17

Description

Key is null in map when OrcNewInputFormat is used as Input Format Class

When using OrcNewInputFormat as input format class for my map reduce job, I find its key is always null in my map method. This gives me no way to get row number in my map method. If you compare RCFileInputFormat (for RC file), its key in map method returns the row number so I know which row I am processing.

Is there any workaround for me to get the row number from my map method? Of course, I can count the row number by myself. But that has two problems: #1 I have to assume the row is coming in the order; #2 I will get duplicated (and wrong) row numbers if a big input file causes multiple file splits (which will trigger my map method multiple times in different data nodes). At this point, I am really seeking a better way to get row number for each processed row in map method.

Here is what I have in my map logs:

[2014-08-06 09:39:25 DEBUG com.xxxx.hadoop.orcfile.OrcFileMap]: Mapper Input Key: (null)
[2014-08-06 09:39:25 DEBUG com.xxxx.hadoop.orcfile.OrcFileMap]: Mapper Input Value:

{Q81510000, T99760000, 699760000, 81567560000, 9667981610000, 978989898980000, Laura, [e-mail]}

My map method is:

protected void map(Object key, Writable value, Context context)
throws IOException, InterruptedException

{ logger.debug("Mapper Input Key: " + key); logger.debug("Mapper Input Value: " + value.toString()); ..... }

The fix should be: add following statement in nextKeyValue() method and pass the result all the way up to the map() method as its key:

reader.getRowNumber();

Issue Links

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