[jira] [Commented] (HBASE-16296) Reverse scan performance degrades when scanner cache size matches page filter size

[Ted Yu (JIRA)]

    [ 
https://issues.apache.org/jira/browse/HBASE-16296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15400164#comment-15400164
 ] 

Ted Yu commented on HBASE-16296:
--------------------------------

I wonder if the following change would help :
{code}
diff --git 
a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java 
b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
index 89e723e..fa3836f 100644
--- 
a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
+++ 
b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
@@ -5951,6 +5951,10 @@ public class HRegion implements HeapSize, 
PropagatingConfigurationObserver, Regi
           // Technically, if we hit limits before on this row, we don't need 
this call.
           if (filterRowKey(current)) {
             incrementCountOfRowsFilteredMetric(scannerContext);
+            if (isFilterDoneInternal()) {
+                return 
scannerContext.setScannerState(NextState.NO_MORE_VALUES).hasMoreValues();
+            }
+
             // Typically the count of rows scanned is incremented inside 
#populateResult. However,
             // here we are filtering a row based purely on its row key, 
preventing us from calling
             // #populateResult. Thus, perform the necessary increment here to 
rows scanned metric
{code}

> Reverse scan performance degrades when scanner cache size matches page filter 
> size
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-16296
>                 URL: https://issues.apache.org/jira/browse/HBASE-16296
>             Project: HBase
>          Issue Type: Bug
>            Reporter: James Taylor
>         Attachments: 16296-MAYBE.txt, generatedata-snippet.java, 
> repro-snippet.java
>
>
> When a reverse scan is done, the server seems to not know it's done when the 
> scanner cache size matches the number of rows in a PageFilter. See 
> PHOENIX-3121 for how this manifests itself. We have a standalone, pure HBase 
> API reproducer too that I'll attach (courtesy of [~churromorales] and 
> [~mujtabachohan]).



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