[HBASE-7189] Adjacent column with timestamp=0 marked for deletion inadvertently

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Cannot Reproduce
• Affects Version/s: 0.92.1
• Component/s: Deletes
• Labels: beginner

Environment

Ubuntu 10.04.2 LTS
2.6.32-28-server #55-Ubuntu SMP Mon Jan 10 23:57:16 UTC 2011 x86_64 GNU/Linux
Cloudera distro 0.92.1-cdh4.1.2

• Assignee: Unassigned
• Reporter: Chris Larsen
• Created: 19/Nov/12 21:22
• Updated: 15/Jun/22 00:24
• Resolved: 15/Jun/22 00:24

Description

This is an esoteric issue that I ran into. We're using binary arrays for column names and "compact" the columns from old rows into a single column to reduce storage usage. The column names are concatenated to create the new qualifier. On accident, I was setting the timestamp to 0 when storing the concatenated column. When I went to delete the old columns, the concatenated column with a timestamp of 0 was also deleted when it should not have been.

Here are some of the columns in the row (taken from the shell utility)

hbase(main):002:0> get 'mytable', "\x00\x01\xAA\x50\x8E\xC4\x20\x00\x00\x01\x00\x00\xAC"
COLUMN CELL
t:\x00\x17 timestamp=1351533601998, value=\x00\x00\x00\x00O\xB2\xDC[
t:\x00\x17\x03\xD7\x...(long name) timestamp=0, value=\x00\x00\x... lots of binary data....
t:\x03\xD7 timestamp=1351533661458, value=\x00\x00\x00\x00O\xB9\xD1\xE5
t:\x07\x97 timestamp=1351533721758, value=\x00\x00\x00\x00O\xBC#\xD0
t:\x0BW timestamp=1351533781738, value=\x00\x00\x00\x00O\xBD\xB93

I wanted to delete the column “t:\x00\x17” but every time I did, the column “t:\x00\x17\x03\xD7\x...” would also be deleted so that I’d wind up with:

hbase(main):005:0> get 'mytable', "\x00\x01\xAA\x50\x8E\xC4\x20\x00\x00\x01\x00\x00\xAC"
COLUMN CELL
t:\x03\xD7 timestamp=1351533661458, value=\x00\x00\x00\x00O\xB9\xD1\xE5
t:\x07\x97 timestamp=1351533721758, value=\x00\x00\x00\x00O\xBC#\xD0
t:\x0BW timestamp=1351533781738, value=\x00\x00\x00\x00O\xBD\xB93

My JAVA test code for the delete looked like this:

HTableInterface table = factory.createHTableInterface(config, "mytable".getBytes());
Delete delete = new Delete(HexToBytes("0001AA508EC4200000010000AC"));
delete.deleteColumn("t".getBytes(), new byte[]

{ (byte) 0x00, (byte) 0x17 }

);
table.delete(delete);

Setting a positive timestamp for the concatenated field solved my issue, but if someone else wants to use timestamps of 0, they may run into the same problem.

NOTE: I also ran into the problem on hbase-0.90.4-cdh3u3