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https://issues.apache.org/jira/browse/HBASE-29357?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tak-Lon (Stephen) Wu resolved HBASE-29357.
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Resolution: Fixed
Thanks again [~junegunn]
> PerformanceEvaluation: Read tests should not drop existing table
> ----------------------------------------------------------------
>
> Key: HBASE-29357
> URL: https://issues.apache.org/jira/browse/HBASE-29357
> Project: HBase
> Issue Type: Bug
> Components: PE
> Affects Versions: 4.0.0-alpha-1
> Reporter: Junegunn Choi
> Assignee: Junegunn Choi
> Priority: Major
> Labels: pull-request-available
> Fix For: 4.0.0-alpha-1, 2.7.0, 3.0.0-beta-2, 2.6.3
>
>
> h2. Problem
> A read test such as {{randomRead}} might drop an existing table when the
> specified {{--presplit}} value is not consistent with the current number of
> regions of the table.
> {code:java}
> # Generate data
> bin/hbase pe --nomapred --size=2 --presplit=30 sequentialWrite 1
> # Perform a read test on the table. Forgot to remove --presplit option, but
> it's okay.
> bin/hbase pe --nomapred --size=2 --presplit=30 --sampleRate=0.1
> sequentialRead 1
> # But if the number of the regions has changed
> bin/hbase shell -n <<< "split 'TestTable'"
> # The --presplit option will cause recreation of the table.
> bin/hbase pe --nomapred --size=2 --presplit=30 --sampleRate=0.1
> sequentialRead 1
> # Operation: DISABLE, Table Name: default:TestTable completed
> # Operation: DELETE, Table Name: default:TestTable completed
> # Operation: CREATE, Table Name: default:TestTable completed
> {code}
> One might say it's wrong to put a {{--presplit}} value in a read test, yes,
> but even so, it should not cause recreation of the table, which makes the
> following read test meaningless.
> h2. Analysis
> There are currently 4 conditions for recreating the table.
> {code:java}
> if (
> (exists && opts.presplitRegions != DEFAULT_OPTS.presplitRegions
> && opts.presplitRegions != admin.getRegions(tableName).size())
> || (!isReadCmd && desc != null
> && !StringUtils.equals(desc.getRegionSplitPolicyClassName(),
> opts.splitPolicy))
> || (!(isReadCmd || isDeleteCmd) && desc != null
> && desc.getRegionReplication() != opts.replicas)
> || (desc != null && desc.getColumnFamilyCount() != opts.families)
> ) {
> needsDelete = true;
> {code}
> But they are inconsistent in how they treat {{{}isReadCmd{}}}.
> h2. Suggestion
> *Premise: never drop an existing table unless executing a write command.*
> ||Condition||Current behavior||Suggested behavior||
> |Region count changed|{color:#de350b}Table recreated{color}|Proceed the test
> with a warning|
> |Split policy changed|No warning|Proceed the test with a warning|
> |Replication factor changed|No warning|Proceed the test with a warning|
> |CF count changed|{color:#de350b}Table recreated{color}|Abort the test with a
> warning|
> * Change of region count or split policy shouldn't affect read tests, so
> it's better to proceed the test but with a warning.
> * I can also imagine wanting to perform a read test with {{--replicas=1}}
> even when the table has a different setting.
> * Technically, we can still run a read test if the current number of CFs is
> greater than the requested number of CFs, but I decided not to allow it to
> avoid confusion.
> h2. Result
> {code:java}
> bin/hbase pe --nomapred --size=2 --presplit=30 --sampleRate=0.1
> sequentialRead 1
> # Inconsistent table state detected. Consider running a write command
> first: [--presplit=30, but found 60 regions]
> bin/hbase pe --nomapred --size=2 --presplit=30 --replicas=2 --sampleRate=0.1
> sequentialRead 1
> # Inconsistent table state detected. Consider running a write command
> first: [--presplit=30, but found 60 regions], [--replicas=2, but found 1
> replicas]
> bin/hbase pe --nomapred --size=2 --presplit=30 --replicas=2
> --splitPolicy=org.apache.hadoop.hbase.regionserver.DisabledRegionSplitPolicy
> --sampleRate=0.1 sequentialRead 1
> # Inconsistent table state detected. Consider running a write command
> first: [--presplit=30, but found 60 regions],
> [--splitPolicy=org.apache.hadoop.hbase.regionserver.DisabledRegionSplitPolicy,
> but current policy is null], [--replicas=2, but found 1 replicas]
> bin/hbase pe --nomapred --size=2 --presplit=30 --replicas=2
> --splitPolicy=org.apache.hadoop.hbase.regionserver.DisabledRegionSplitPolicy
> --families=2 --sampleRate=0.1 sequentialRead 1
> # java.lang.IllegalStateException: Cannot proceed the test. Run a write
> command first: --families=2, but found 1 column families
> {code}
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