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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11772) Bulk load mvcc and seqId issues with native hfiles
Date Fri, 05 Sep 2014 06:52:32 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11772?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14122520#comment-14122520
] 

Anoop Sam John commented on HBASE-11772:
----------------------------------------

In your eg: you were telling "hfile named 'abc_SeqId_10_' can exist in HBase"
But I got it now.  The file can be already a bulk loaded one and so seqId_ part already in
name. Again when u load this to another table, second seqId_ part can come in. So yes, for
getting the actual seq_id of the file, go with lastIndexOf() and there is no issue with this
check to know whether this is a bulk loaded one or not.
{code}
+    String fileName = this.getPath().getName();
+    int startPos = fileName.indexOf("SeqId_");
+    if (startPos != -1) {
+      bulkLoadedHFile = true;
+    }{code}
This is what ur thinking?

[~tedyu] was asking why the change to lastIndexOf().


> 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
>            Assignee: Jerry He
>            Priority: Critical
>             Fix For: 0.99.0, 1.0.0, 2.0.0, 0.98.7
>
>         Attachments: HBASE-11772-0.98.patch, HBASE-11772-master-v1.patch
>
>
> 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 cells. 
> 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:
> {code}
> return metadataMap.containsKey(BULKLOAD_TIME_KEY)
> {code}
> 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.



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