hbase-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jerry He (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-11772) Bulk load mvcc and seqId issues with native hfiles
Date Mon, 18 Aug 2014 20:09:20 GMT
Jerry He created HBASE-11772:

             Summary: Bulk load mvcc and seqId issues with native hfiles
                 Key: HBASE-11772
                 URL: https://issues.apache.org/jira/browse/HBASE-11772
             Project: HBase
          Issue Type: Bug
    Affects Versions: 0.98.5
            Reporter: Jerry He

There are mvcc and seqId issues when bulk load native hfiles -- meaning hfiles that are direct
file copy-out from hbase, not from HFileOutputFormat job.

There are differences between these two types of hfiles.
Native hfiles have possible non-zero MAX_MEMSTORE_TS_KEY value and non-zero mvcc values in
Native hfiles also have MAX_SEQ_ID_KEY.
Native hfiles do not have BULKLOAD_TIME_KEY.

Here are a couple of problems I observed when bulk load native hfiles.

1.  Cells in newly bulk loaded hfiles can be invisible to scan.

It is easy to re-create.
Bulk load a native hfile that has a larger mvcc value in cells, e.g 10
If the current readpoint when initiating a scan is less than 10, the cells in the new hfile
are skipped, thus become invisible.
We don't reset the readpoint of a region after bulk load.

2. The current StoreFile.isBulkLoadResult() is implemented as:
return metadataMap.containsKey(BULKLOAD_TIME_KEY)
which does not detect bulkloaded native hfiles.

3. Another observed problem is possible data loss during log recovery. 
It is similar to HBASE-10958 reported by [~jdcryans]. Borrow the re-create steps from HBASE-10958.

1) Create an empty table
2) Put one row in it (let's say it gets seqid 1)
3) Bulk load one native hfile with large seqId ( e.g. 100). The native hfile can be obtained
by copying out from existing table.
4) Kill the region server that holds the table's region.
Scan the table once the region is made available again. The first row, at seqid 1, will be
missing since the HFile with seqid 100 makes us believe that everything that came before it
was flushed. 

The problem 3 is probably related to 2. We will be ok if we get the appended seqId during
bulk load instead of 100 from inside the file.

This message was sent by Atlassian JIRA

View raw message