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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13109) Make better SEEK vs SKIP decisions during scanning
Date Thu, 05 Mar 2015 03:06:39 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13109?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14348043#comment-14348043
] 

Hudson commented on HBASE-13109:
--------------------------------

SUCCESS: Integrated in HBase-0.98-on-Hadoop-1.1 #840 (See [https://builds.apache.org/job/HBase-0.98-on-Hadoop-1.1/840/])
HBASE-13109 Make better SEEK vs SKIP decisions during scanning. (larsh: rev b3bd0016492eb99e3a83353f0879bfddebff4ec1)
* hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestExplicitColumnTracker.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ExplicitColumnTracker.java
* hbase-client/src/main/java/org/apache/hadoop/hbase/client/Scan.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/NonLazyKeyValueScanner.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ScanQueryMatcher.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/KeyValueScanner.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/KeyValueHeap.java
* hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestQueryMatcher.java
* hbase-common/src/main/java/org/apache/hadoop/hbase/KeyValue.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileReaderV2.java
* hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestBlocksRead.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreScanner.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFileScanner.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/HalfStoreFileReader.java
* hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileScanner.java


> Make better SEEK vs SKIP decisions during scanning
> --------------------------------------------------
>
>                 Key: HBASE-13109
>                 URL: https://issues.apache.org/jira/browse/HBASE-13109
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>             Fix For: 2.0.0, 1.0.1, 1.1.0, 0.98.12
>
>         Attachments: 13109-0.98-v4.txt, 13109-trunk-v2.txt, 13109-trunk-v3.txt, 13109-trunk-v4.txt,
13109-trunk-v5.txt, 13109-trunk.txt, nextIndexKVChange_new.patch
>
>
> I'm re-purposing this issue to add a heuristic as to when to SEEK and when to SKIP Cells.
This has come up in various issues, and I think I have a way to finally fix this now. HBASE-9778,
HBASE-12311, and friends are related.
> --- Old description ---
> This is a continuation of HBASE-9778.
> We've seen a scenario of a very slow scan over a region using a timerange that happens
to fall after the ts of any Cell in the region.
> Turns out we spend a lot of time seeking.
> Tested with a 5 column table, and the scan is 5x faster when the timerange falls before
all Cells' ts.
> We can use the lookahead hint introduced in HBASE-9778 to do opportunistic SKIPing before
we actually seek.



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