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Hadoop QA commented on HBASE-4811: ---------------------------------- {color:red}-1 overall{color}. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12616305/4811-trunk-v29.patch against trunk revision . {color:green}+1 @author{color}. The patch does not contain any @author tags. {color:green}+1 tests included{color}. The patch appears to include 18 new or modified tests. {color:green}+1 hadoop1.0{color}. The patch compiles against the hadoop 1.0 profile. {color:green}+1 hadoop2.0{color}. The patch compiles against the hadoop 2.0 profile. {color:green}+1 javadoc{color}. The javadoc tool did not generate any warning messages. {color:green}+1 javac{color}. The applied patch does not increase the total number of javac compiler warnings. {color:green}+1 findbugs{color}. The patch does not introduce any new Findbugs (version 1.3.9) warnings. {color:green}+1 release audit{color}. The applied patch does not increase the total number of release audit warnings. {color:green}+1 lineLengths{color}. The patch does not introduce lines longer than 100 {color:red}-1 site{color}. The patch appears to cause mvn site goal to fail. {color:green}+1 core tests{color}. The patch passed unit tests in . Test results: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//testReport/ Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-prefix-tree.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-client.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-common.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-protocol.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-server.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop1-compat.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-examples.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-thrift.html Findbugs warnings: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//artifact/trunk/patchprocess/newPatchFindbugsWarningshbase-hadoop-compat.html Console output: https://builds.apache.org/job/PreCommit-HBASE-Build/8027//console This message is automatically generated. > Support reverse Scan > -------------------- > > Key: HBASE-4811 > URL: https://issues.apache.org/jira/browse/HBASE-4811 > Project: HBase > Issue Type: New Feature > Components: Client > Affects Versions: 0.20.6, 0.94.7 > Reporter: John Carrino > Assignee: chunhui shen > Fix For: 0.98.0, 0.96.1, 0.94.15 > > Attachments: 4811-0.94-v22.txt, 4811-0.94-v23.txt, 4811-0.94-v3.txt, > 4811-trunk-v10.txt, 4811-trunk-v29.patch, 4811-trunk-v5.patch, > HBase-4811-0.94-v2.txt, HBase-4811-0.94.3modified.txt, hbase-4811-0.94 > v21.patch, hbase-4811-0.94-v24.patch, hbase-4811-trunkv1.patch, > hbase-4811-trunkv11.patch, hbase-4811-trunkv12.patch, > hbase-4811-trunkv13.patch, hbase-4811-trunkv14.patch, > hbase-4811-trunkv15.patch, hbase-4811-trunkv16.patch, > hbase-4811-trunkv17.patch, hbase-4811-trunkv18.patch, > hbase-4811-trunkv19.patch, hbase-4811-trunkv20.patch, > hbase-4811-trunkv21.patch, hbase-4811-trunkv24.patch, > hbase-4811-trunkv24.patch, hbase-4811-trunkv25.patch, > hbase-4811-trunkv26.patch, hbase-4811-trunkv27.patch, > hbase-4811-trunkv28.patch, hbase-4811-trunkv4.patch, > hbase-4811-trunkv6.patch, hbase-4811-trunkv7.patch, hbase-4811-trunkv8.patch, > hbase-4811-trunkv9.patch > > > Reversed scan means scan the rows backward. > And StartRow bigger than StopRow in a reversed scan. > For example, for the following rows: > aaa/c1:q1/value1 > aaa/c1:q2/value2 > bbb/c1:q1/value1 > bbb/c1:q2/value2 > ccc/c1:q1/value1 > ccc/c1:q2/value2 > ddd/c1:q1/value1 > ddd/c1:q2/value2 > eee/c1:q1/value1 > eee/c1:q2/value2 > you could do a reversed scan from 'ddd' to 'bbb'(exclude) like this: > Scan scan = new Scan(); > scan.setStartRow('ddd'); > scan.setStopRow('bbb'); > scan.setReversed(true); > for(Result result:htable.getScanner(scan)){ > System.out.println(result); > } > Aslo you could do the reversed scan with shell like this: > hbase> scan 'table',{REVERSED => true,STARTROW=>'ddd', STOPROW=>'bbb'} > And the output is: > ddd/c1:q1/value1 > ddd/c1:q2/value2 > ccc/c1:q1/value1 > ccc/c1:q2/value2 > NOTE: when setting reversed as true for a client scan, you must set the start > row, else will throw exception. Through {@link > Scan#createBiggestByteArray(int)},you could get a big enough byte array as > the start row > All the documentation I find about HBase says that if you want forward and > reverse scans you should just build 2 tables and one be ascending and one > descending. Is there a fundamental reason that HBase only supports forward > Scan? It seems like a lot of extra space overhead and coding overhead (to > keep them in sync) to support 2 tables. > I am assuming this has been discussed before, but I can't find the > discussions anywhere about it or why it would be infeasible. -- This message was sent by Atlassian JIRA (v6.1#6144)