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https://issues.apache.org/jira/browse/HBASE-4071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13089940#comment-13089940
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[email protected] commented on HBASE-4071:
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bq. On 2011-08-24 00:03:43, Michael Stack wrote:
bq. >
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ExplicitColumnTracker.java,
line 127
bq. > <https://reviews.apache.org/r/1582/diff/7/?file=34607#file34607line127>
bq. >
bq. > I defer to Jon's review here (he knows this stuff...)
This basically just counts versions up instead of down (see next comment below
as to why).
bq. On 2011-08-24 00:03:43, Michael Stack wrote:
bq. >
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ExplicitColumnTracker.java,
line 205
bq. > <https://reviews.apache.org/r/1582/diff/7/?file=34607#file34607line205>
bq. >
bq. > Why this change?
ExplicitColumnTracker used to count versions down and ScanWildcardColumnTracker
is counting version up.
This change goes to together with the previous change (increment vs decrement).
I did that for two reasons:
1. When both column trackers follow similar logic it will be easier to change
them and to simplify them further in the future (such as extracting a GC
policy).
2. Now the comparison for versions can be:
if(count >= maxVersions || (count >= minVersions && isExpired(timestamp))
// Done with versions for this column
whereas otherwise it would need to be:
if(count == 0) || ((maxVersion-count) < minVersions && isExpired(timestamp))
// Done with versions for this column
Which is harder to read and less intuitive, I think.
bq. On 2011-08-24 00:03:43, Michael Stack wrote:
bq. >
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ColumnTracker.java,
line 47
bq. > <https://reviews.apache.org/r/1582/diff/7/?file=34606#file34606line47>
bq. >
bq. > javadoc doesn't match param name -- I can fix on commit.
Argh... One more that I missed. Thanks Stack!
- Lars
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On 2011-08-23 05:13:38, Lars Hofhansl wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/1582/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-08-23 05:13:38)
bq.
bq.
bq. Review request for hbase, Todd Lipcon, Michael Stack, and Jonathan Gray.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. Allow enforcing a minimum number of versions when TTL is enable for a
store.
bq. The GC logic for both versions and TTL is unified inside the
ColumnTrackers.
bq.
bq.
bq. This addresses bug HBASE-4071.
bq. https://issues.apache.org/jira/browse/HBASE-4071
bq.
bq.
bq. Diffs
bq. -----
bq.
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/HColumnDescriptor.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ColumnTracker.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ExplicitColumnTracker.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ScanQueryMatcher.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/ScanWildcardColumnTracker.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/Store.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java
1160440
bq. http://svn.apache.org/repos/asf/hbase/trunk/src/main/ruby/hbase/admin.rb
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestCase.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestExplicitColumnTracker.java
1160440
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestMinVersions.java
PRE-CREATION
bq.
http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestScanWildcardColumnTracker.java
1160440
bq.
bq. Diff: https://reviews.apache.org/r/1582/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq. Ran all tests. I get error (not failures) from two:
TestDistributedLogSplitting and TestHTablePool. Both fail with or without my
changes.
bq. New tests: TestMinVersions.
bq.
bq.
bq. Thanks,
bq.
bq. Lars
bq.
bq.
> Data GC: Remove all versions > TTL EXCEPT the last written version
> ------------------------------------------------------------------
>
> Key: HBASE-4071
> URL: https://issues.apache.org/jira/browse/HBASE-4071
> Project: HBase
> Issue Type: New Feature
> Reporter: stack
> Assignee: Lars Hofhansl
> Attachments: MinVersions.diff
>
>
> We were chatting today about our backup cluster. What we want is to be able
> to restore the dataset from any point of time but only within a limited
> timeframe -- say one week. Thereafter, if the versions are older than one
> week, rather than as we do with TTL where we let go of all versions older
> than TTL, instead, let go of all versions EXCEPT the last one written. So,
> its like versions==1 when TTL > one week. We want to allow that if an error
> is caught within a week of its happening -- user mistakenly removes a
> critical table -- then we'll be able to restore up the the moment just before
> catastrophe hit otherwise, we keep one version only.
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