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https://issues.apache.org/jira/browse/HBASE-6331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13406934#comment-13406934
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ramkrishna.s.vasudevan edited comment on HBASE-6331 at 7/5/12 9:33 AM:
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This issue we observed after doing -fixSplitParents..followed by hbck -fix and
hbck -repair. I think we may need documentation here on the usage of
fixSplitParents.
Parent region A got split into A1 and A2.
A -> startkey = 'x' and endkey = ''.
So A1 -> startkey = 'x' and endkey = 'x1'
A2 -> startkey = 'x1' and endkey =''.
Here while reading the hdfs hbck finds there are 2 regions with same start key
and 1 region that overlaps.
{code}
ERROR: (region
ufdr,010193811093051,1341438516341.cd3d13f6574059498ceded9661e136cd.) Multiple
regions have the same startkey: 010193811093051
ERROR: (region
ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0.) Multiple
regions have the same startkey: 010193811093051
ERROR: (regions
ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0. and
ufdr,010196915311117,1341438516341.865326e49dfa71996a92dfa5e45c6977.) There is
an overlap in the region chain.
{code}
{code}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010193811093051,1341438516341.cd3d13f6574059498ceded9661e136cd.',
STARTKEY => '010193811093051', ENDKEY => '010196915311117', ENCODED =>
cd3d13f6574059498ceded9661e136cd,}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0.',
STARTKEY => '010193811093051', ENDKEY => '', ENCODED =>
e3af982dffd49d785f76ab6e5aa36fc0,}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010196915311117,1341438516341.865326e49dfa71996a92dfa5e45c6977.',
STARTKEY => '010196915311117', ENDKEY => '', ENCODED =>
865326e49dfa71996a92dfa5e45c6977,}
{code}
Now finally while fixing this HBCK creates a region which does not have empty
start key.
We can try fixing HBASE-6223 so that we are clear on the usage of
-fixSplitParents.
was (Author: ram_krish):
This issue we observed after doing -fixSplitParents..followed by hbck -fix
and hbck -repair. I think we may need documentation here on the usage of
fixSplitParents.
Parent region A got split into A1 and A2.
A -> startkey = 'x' and endkey = ''.
So A1 -> startkey = 'x' and endkey = 'x1'
A2 -> startkey = 'x1' and endkey =''.
Here while reading the hdfs hbck finds there are 2 regions with same start key
and 1 region that overlaps.
{code}
ERROR: (region
ufdr,010193811093051,1341438516341.cd3d13f6574059498ceded9661e136cd.) Multiple
regions have the same startkey: 010193811093051
ERROR: (region
ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0.) Multiple
regions have the same startkey: 010193811093051
ERROR: (regions
ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0. and
ufdr,010196915311117,1341438516341.865326e49dfa71996a92dfa5e45c6977.) There is
an overlap in the region chain.
{code}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010193811093051,1341438516341.cd3d13f6574059498ceded9661e136cd.',
STARTKEY => '010193811093051', ENDKEY => '010196915311117', ENCODED =>
cd3d13f6574059498ceded9661e136cd,}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010193811093051,1341438202996.e3af982dffd49d785f76ab6e5aa36fc0.',
STARTKEY => '010193811093051', ENDKEY => '', ENCODED =>
e3af982dffd49d785f76ab6e5aa36fc0,}
12/07/05 11:14:09 DEBUG util.HBaseFsck: HRegionInfo read: {NAME =>
'ufdr,010196915311117,1341438516341.865326e49dfa71996a92dfa5e45c6977.',
STARTKEY => '010196915311117', ENDKEY => '', ENCODED =>
865326e49dfa71996a92dfa5e45c6977,}
{code}
Now finally while fixing this HBCK creates a region which does not have empty
start key.
We can try fixing HBASE-6223 so that we are clear on the usage of
-fixSplitParents.
> Problem with HBCK mergeOverlaps
> -------------------------------
>
> Key: HBASE-6331
> URL: https://issues.apache.org/jira/browse/HBASE-6331
> Project: HBase
> Issue Type: Bug
> Components: hbck
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 0.96.0, 0.94.1
>
> Attachments: HBASE-6331_94.patch, HBASE-6331_Trunk.patch
>
>
> In HDFSIntegrityFixer#mergeOverlaps(), there is a logic to create the final
> range of the region after the overlap.
> I can see one issue with this code
> {code}
> if (RegionSplitCalculator.BYTES_COMPARATOR
> .compare(hi.getEndKey(), range.getSecond()) > 0) {
> range.setSecond(hi.getEndKey());
> }
> {code}
> Here suppose the regions include the end region for which the endKey will be
> empty, we need to get finally the range with endkey as empty byte[]
> But as per the above logic it will see that any other key greater than the
> empty byte[] and will set it.
> Finally the new region created will not get endkey as empty byte[]
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