[jira] [Commented] (PHOENIX-1751) Perform aggregations, sorting, etc, in the preScannerOpen instead of postScannerOpen

["Hadoop QA (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PHOENIX-1751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15429242#comment-15429242 ] 

Hadoop QA commented on PHOENIX-1751:
------------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12824688/PHOENIX-1751_v3.patch
  against master branch at commit 386cbbbf7a5dd736888e8e0bfe16e513d54e215c.
  ATTACHMENT ID: 12824688

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include any new or modified tests.
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of javac compiler warnings.

    {color:red}-1 javadoc{color}.  The javadoc tool appears to have generated 34 warning messages.

    {color:green}+1 release audit{color}.  The applied patch does not increase the total number of release audit warnings.

    {color:red}-1 lineLengths{color}.  The patch introduces the following lines longer than 100:
    +    abstract protected RegionScanner getRegionScanner(ObserverContext<RegionCoprocessorEnvironment> c, final Scan scan, final RegionScanner s) throws Throwable;
+                    // We are setting the start row and stop row such that it covers the entire region. As part
+                    // of Phonenix-1263 we are storing the guideposts against the physical table rather than
+                // and region servers to crash. See https://issues.apache.org/jira/browse/PHOENIX-1596
+    protected RegionScanner getRegionScanner(final ObserverContext<RegionCoprocessorEnvironment> c, final Scan scan, final RegionScanner s) throws Throwable {
+    protected RegionScanner getRegionScanner(final ObserverContext<RegionCoprocessorEnvironment> c, final Scan scan, final RegionScanner s) throws IOException {

    {color:green}+1 core tests{color}.  The patch passed unit tests in .

Test results: https://builds.apache.org/job/PreCommit-PHOENIX-Build/527//testReport/
Javadoc warnings: https://builds.apache.org/job/PreCommit-PHOENIX-Build/527//artifact/patchprocess/patchJavadocWarnings.txt
Console output: https://builds.apache.org/job/PreCommit-PHOENIX-Build/527//console

This message is automatically generated.

> Perform aggregations, sorting, etc, in the preScannerOpen instead of postScannerOpen
> ------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-1751
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-1751
>             Project: Phoenix
>          Issue Type: Bug
>            Reporter: Lars Hofhansl
>            Assignee: James Taylor
>         Attachments: 1751-WIP-v2.txt, 1751-WIP-v2b.patch, 1751-WIP.txt, PHOENIX-1751-v2c.patch, PHOENIX-1751.patch, PHOENIX-1751_v3.patch
>
>
> HBase retains a lease for every scanner. Then lease expires the scan will no longer (be allowed to) work. The leases guard against the client going away, and allow cleaning up resources if that happens.
> At various points HBase "suspends" the lease while the region server are working on behalf of this scanner, so that the lease won't expire even though the server is working on it.
> HBase does that during the scanning process. Crucially it suspends the leaser after the scanner is opened, before next() is issued on it.
> The outcome of all this is that Phoenix executes aggregates, sorts, etc, with the lease in place, and hence if these take a bit the lease can expire even though the server was working on it.
> Phoenix should do this work in preScannerNext, being careful that the precalculation is only performed once.
> I'll attach a sample patch soon.



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