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https://issues.apache.org/jira/browse/HBASE-2600?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13188642#comment-13188642
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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/3466/
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(Updated 2012-01-18 19:21:37.796315)
Review request for hbase, Michael Stack and Lars Hofhansl.
Summary (updated)
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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
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src/main/java/org/apache/hadoop/hbase/HRegionInfo.java 74cb821
src/main/java/org/apache/hadoop/hbase/HConstants.java 8370ef8
src/main/java/org/apache/hadoop/hbase/HTableDescriptor.java 133759d
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 88c381f
src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java d857538
src/main/java/org/apache/hadoop/hbase/client/HTable.java 57605e6
src/main/java/org/apache/hadoop/hbase/client/HTableInterface.java 784fdc2
src/main/java/org/apache/hadoop/hbase/client/HTablePool.java a5c198f
src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java f0c6828
src/main/java/org/apache/hadoop/hbase/coprocessor/BaseRegionObserver.java
7a7b896
src/main/java/org/apache/hadoop/hbase/coprocessor/CoprocessorHost.java
b1b5a78
src/main/java/org/apache/hadoop/hbase/coprocessor/RegionObserver.java c0a4184
src/main/java/org/apache/hadoop/hbase/ipc/HRegionInterface.java 0431444
src/main/java/org/apache/hadoop/hbase/master/handler/ServerShutdownHandler.java
4307d89
src/main/java/org/apache/hadoop/hbase/regionserver/GetClosestRowBeforeTracker.java
3a26bbb
src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java c7cc402
src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java 5cb606f
src/main/java/org/apache/hadoop/hbase/regionserver/MemStore.java 50e7fe0
src/main/java/org/apache/hadoop/hbase/regionserver/RegionCoprocessorHost.java
a3850e5
src/main/java/org/apache/hadoop/hbase/regionserver/Store.java 636e533
src/main/java/org/apache/hadoop/hbase/rest/RegionsResource.java bf85bc1
src/main/java/org/apache/hadoop/hbase/rest/client/RemoteHTable.java 3919985
src/main/java/org/apache/hadoop/hbase/rest/model/TableRegionModel.java
67e7a04
src/main/java/org/apache/hadoop/hbase/thrift/ThriftServerRunner.java b6a6349
src/main/java/org/apache/hadoop/hbase/thrift/generated/Hbase.java 9e31c61
src/main/resources/org/apache/hadoop/hbase/thrift/Hbase.thrift 5821d31
src/test/java/org/apache/hadoop/hbase/TestKeyValue.java dc4ee8d
src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java 95ab8e6
src/test/java/org/apache/hadoop/hbase/coprocessor/SimpleRegionObserver.java
dacb936
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/TestMinVersions.java
33c78ab
src/test/java/org/apache/hadoop/hbase/rest/TestStatusResource.java cffdcb6
src/test/java/org/apache/hadoop/hbase/rest/model/TestTableRegionModel.java
b6f0ab5
Diff: https://reviews.apache.org/r/3466/diff
Testing
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Unit tests started table.
Tests in error:
org.apache.hadoop.hbase.client.TestMetaMigrationRemovingHTD: Table 'TestTable
we searched for the StartKey: TestTable ,, startKey lastChar's int value: 32
with the stopKey: TestTable#,, stopRow lastChar's int value: 35 with
parentTable:.META.
I need to know how to update/recreate the tar ball which is the source for that
test.
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: Bug
> Reporter: stack
> Assignee: Alex Newman
> Attachments:
> 0001-Changed-regioninfo-format-to-use-endKey-instead-of-s.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v2.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v4.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v6.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v7.2.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v8,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v8.1,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen-v9.patch,
> 0001-HBASE-2600.-Change-how-we-do-meta-tables-from-tablen.patch,
> 2600-trunk-01-17.txt, jenkins.pdf
>
>
> 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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