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https://issues.apache.org/jira/browse/HBASE-2600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13172629#comment-13172629
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jirapos...@reviews.apache.org commented on HBASE-2600:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/3186/
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(Updated 2011-12-19 21:25:51.965234)
Review request for hbase.
Summary
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PART 1 of hbase-4616
This is an idea that Ryan and I have been kicking around on and off for a while
now.
If regionnames were made of tablename+endrow instead of tablename+startrow,
then in the metatables, doing a search for the region that contains the wanted
row, we'd just have to open a scanner using passed row and the first row found
by the scan would be that of the region we need (If offlined parent, we'd have
to scan to the next row).
If we redid the meta tables in this format, we'd be using an access that is
natural to hbase, a scan as opposed to the perverse, expensive
getClosestRowBefore we currently have that has to walk backward in meta finding
a containing region.
This issue is about changing the way we name regions.
If we were using scans, prewarming client cache would be near costless (as
opposed to what we'll currently have to do which is first a getClosestRowBefore
and then a scan from the closestrowbefore forward).
Converting to the new method, we'd have to run a migration on startup changing
the content in meta.
Up to this, the randomid component of a region name has been the timestamp of
region creation. HBASE-2531 "32-bit encoding of regionnames waaaaaaayyyyy too
susceptible to hash clashes" proposes changing the randomid so that it contains
actual name of the directory in the filesystem that hosts the region. If we had
this in place, I think it would help with the migration to this new way of
doing the meta because as is, the region name in fs is a hash of regionname...
changing the format of the regionname would mean we generate a different
hash... so we'd need hbase-2531 to be in place before we could do this change.
This addresses bug HBASE-2600.
https://issues.apache.org/jira/browse/HBASE-2600
Diffs (updated)
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src/main/java/org/apache/hadoop/hbase/rest/RegionsResource.java bf85bc1
src/main/java/org/apache/hadoop/hbase/HRegionInfo.java 74cb821
src/main/java/org/apache/hadoop/hbase/KeyValue.java be7e2d8
src/main/java/org/apache/hadoop/hbase/catalog/MetaReader.java e5e60a8
src/main/java/org/apache/hadoop/hbase/client/HBaseAdmin.java 6bff130
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java d475a1d
src/main/java/org/apache/hadoop/hbase/client/HTable.java 8cc6444
src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java 4135e55
src/main/java/org/apache/hadoop/hbase/client/MetaSearchRow.java PRE-CREATION
src/main/java/org/apache/hadoop/hbase/HConstants.java 3c83846
src/main/java/org/apache/hadoop/hbase/rest/model/TableRegionModel.java
67e7a04
src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java 9ea19e5
src/test/java/org/apache/hadoop/hbase/TestKeyValue.java dc4ee8d
src/test/java/org/apache/hadoop/hbase/client/TestAdmin.java 9f66880
src/test/java/org/apache/hadoop/hbase/regionserver/TestGetClosestAtOrBefore.java
5f97167
src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegionInfo.java
6e1211b
src/test/java/org/apache/hadoop/hbase/regionserver/TestHRegionInfoGetTableName.java
PRE-CREATION
src/test/java/org/apache/hadoop/hbase/regionserver/TestMemStore.java a092cf0
src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java
1997abd
src/test/java/org/apache/hadoop/hbase/rest/model/TestTableRegionModel.java
b6f0ab5
Diff: https://reviews.apache.org/r/3186/diff
Testing
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Thanks,
Alex
> Change how we do meta tables; from tablename+STARTROW+randomid to instead,
> tablename+ENDROW+randomid
> ----------------------------------------------------------------------------------------------------
>
> Key: HBASE-2600
> URL: https://issues.apache.org/jira/browse/HBASE-2600
> Project: HBase
> Issue Type: Sub-task
> Reporter: stack
> Assignee: Alex Newman
> Attachments:
> 0001-Changed-regioninfo-format-to-use-endKey-instead-of-s.patch
>
>
> This is an idea that Ryan and I have been kicking around on and off for a
> while now.
> If regionnames were made of tablename+endrow instead of tablename+startrow,
> then in the metatables, doing a search for the region that contains the
> wanted row, we'd just have to open a scanner using passed row and the first
> row found by the scan would be that of the region we need (If offlined
> parent, we'd have to scan to the next row).
> If we redid the meta tables in this format, we'd be using an access that is
> natural to hbase, a scan as opposed to the perverse, expensive
> getClosestRowBefore we currently have that has to walk backward in meta
> finding a containing region.
> This issue is about changing the way we name regions.
> If we were using scans, prewarming client cache would be near costless (as
> opposed to what we'll currently have to do which is first a
> getClosestRowBefore and then a scan from the closestrowbefore forward).
> Converting to the new method, we'd have to run a migration on startup
> changing the content in meta.
> Up to this, the randomid component of a region name has been the timestamp of
> region creation. HBASE-2531 "32-bit encoding of regionnames waaaaaaayyyyy
> too susceptible to hash clashes" proposes changing the randomid so that it
> contains actual name of the directory in the filesystem that hosts the
> region. If we had this in place, I think it would help with the migration to
> this new way of doing the meta because as is, the region name in fs is a hash
> of regionname... changing the format of the regionname would mean we generate
> a different hash... so we'd need hbase-2531 to be in place before we could do
> this change.
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