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Date: Thu, 17 Aug 2017 02:31:00 +0000 (UTC)
From: "Chia-Ping Tsai (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.13090752.1501241893000.50173.1502937060399@Atlassian.JIRA>
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Subject: [jira] [Commented] (HBASE-18471) The DeleteFamily cell is skipped
 when StoreScanner seeks to next column
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archived-at: Thu, 17 Aug 2017 02:31:06 -0000


    [ https://issues.apache.org/jira/browse/HBASE-18471?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16129780#comment-16129780 ] 

Chia-Ping Tsai commented on HBASE-18471:
----------------------------------------

The bug is due to the key returned from getKeyForNextColumn(). The key say that *we should skip all cells which have the same qualifier with current cell*, so the DeleteFamily is skipped.
ex1: Put (qual1), Delete family, put(qual0, val0), put(qual0, val1)
The *DeleteFamily* always peeks out as the first Cell, so every thing works fine.

ex2: Put (qual1), Delete family, put(empty, val0), put(empty, val1)
The *put(empty, val1)* always peeks out as the first Cell. After put(empty, val0) peeks out, the matcher say "SeekNextColumn". StoreScanner use the key from matcher#getKeyForNextColumn() to seek next column. The layout of the key is shown below:
|row|fam|empty|HConstants.OLDEST_TIMESTAMP|Type.Minimum| 
Hence, the DeleteFamily is skipped because it is larger than the key.

bq. Ideally a cell with qualifier qual0 and a cell without qualifier the cell without qualifier should sort first and then the cell with qualifier.
It seems to me that the CellComparator works normally about this.

bq. I think in CellComparator#compareColums if we can handle this then we are able to solve this issue?
Pardon me, I fail to catch what you mean here.

> The DeleteFamily cell is skipped when StoreScanner seeks to next column
> -----------------------------------------------------------------------
>
>                 Key: HBASE-18471
>                 URL: https://issues.apache.org/jira/browse/HBASE-18471
>             Project: HBase
>          Issue Type: Bug
>          Components: Deletes, hbase, scan
>    Affects Versions: 3.0.0, 1.3.0, 1.3.1, 2.0.0-alpha-1
>            Reporter: Thomas Martens
>            Assignee: Chia-Ping Tsai
>            Priority: Critical
>             Fix For: 2.0.0, 1.4.0, 1.3.2, 1.5.0, 1.2.7
>
>         Attachments: HBASE-18471.branch-1.2.v0.patch, HBASE-18471.v0.patch, HBASE-18471.v1.patch, HBaseDmlTest.java
>
>
> The qualifier of a deleted row (with keep deleted cells true) re-appears after re-inserting the same row multiple times (with different timestamp) with an empty qualifier.
> Scenario:
> # Put row with family and qualifier (timestamp 1).
> # Delete entire row (timestamp 2).
> # Put same row again with family without qualifier (timestamp 3).
> A scan (latest version) returns the row with family without qualifier, version 3 (which is correct).
> # Put the same row again with family without qualifier (timestamp 4).
> A scan (latest version) returns multiple rows:
> * the row with family without qualifier, version 4 (which is correct).
> * the row with family with qualifier, version 1 (which is wrong).
> There is a test scenario attached.
> output:
> <LOG> 13:42:53,952 [main] client.HBaseAdmin - Started disable of test_dml
> <LOG> 13:42:55,801 [main] client.HBaseAdmin - Disabled test_dml
> <LOG> 13:42:57,256 [main] client.HBaseAdmin - Deleted test_dml
> <LOG> 13:42:58,592 [main] client.HBaseAdmin - Created test_dml
> Put row: 'myRow' with family: 'myFamily' with qualifier: 'myQualifier' with timestamp: '1'
> Scan printout =>
>   Row: 'myRow', Timestamp: '1', Family: 'myFamily', Qualifier: 'myQualifier', Value: 'myValue'
> Delete row: 'myRow'
> Scan printout =>
> Put row: 'myRow' with family: 'myFamily' with qualifier: 'null' with timestamp: '3'
> Scan printout =>
>   Row: 'myRow', Timestamp: '3', Family: 'myFamily', Qualifier: '', Value: 'myValue'
> Put row: 'myRow' with family: 'myFamily' with qualifier: 'null' with timestamp: '4'
> Scan printout =>
>   Row: 'myRow', Timestamp: '4', Family: 'myFamily', Qualifier: '', Value: 'myValue'
>   {color:red}Row: 'myRow', Timestamp: '1', Family: 'myFamily', Qualifier: 'myQualifier', Value: 'myValue'{color}


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