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https://issues.apache.org/jira/browse/PHOENIX-6273?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17269485#comment-17269485
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ASF GitHub Bot commented on PHOENIX-6273:
-----------------------------------------
sakshamgangwar commented on a change in pull request #1079:
URL: https://github.com/apache/phoenix/pull/1079#discussion_r562080082
##########
File path:
phoenix-core/src/it/java/org/apache/phoenix/end2end/TableSnapshotReadsMapReduceIT.java
##########
@@ -274,6 +293,9 @@ private void configureJob(Job job, String tableName, String
inputQuery, String c
assertFalse("Should only have stored" + result.size() + "rows in the
table for the timestamp!", rs.next());
} finally {
+ if (isSnapshotRestoreDoneExternally) {
+ assertRestoreDirCount(conf, tmpDir.toString(), 1);
Review comment:
@shahrs87 There were two levels of subdirectories getting created for
snapshot restore on every scan:
https://github.com/apache/phoenix/blob/55f1362fc52eeabed139728dae153518883743a5/phoenix-core/src/main/java/org/apache/phoenix/mapreduce/util/PhoenixMapReduceUtil.java#L185
https://github.com/apache/phoenix/blob/55f1362fc52eeabed139728dae153518883743a5/phoenix-core/src/main/java/org/apache/phoenix/iterate/TableSnapshotResultIterator.java#L81
I have removed those in the original flow so now the directory gets cleaned
up every single scan and gets created again for the next scan with the same
directory structure.
I can assert here no existence of the restore directory in the original
flow.
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> Add support to handle MR Snapshot restore externally
> ----------------------------------------------------
>
> Key: PHOENIX-6273
> URL: https://issues.apache.org/jira/browse/PHOENIX-6273
> Project: Phoenix
> Issue Type: Bug
> Components: core
> Affects Versions: 5.0.0, 4.14.3
> Reporter: Saksham Gangwar
> Assignee: Saksham Gangwar
> Priority: Major
> Fix For: 5.1.0, 4.16.0
>
>
> Recently we switched an MR application from scanning live tables to scanning
> snapshots (PHOENIX-3744). We ran into a severe performance issue, which
> turned out to a correctness issue due to over-lapping scan splits generation.
> After some debugging we figured that it has been fixed via PHOENIX-4997.
> We also *need not restore the snapshot per map task*. Currently, we restore
> the snapshot once per map task into a temp directory. For large tables on big
> clusters, this creates a storm of NN RPCs. We can do this once per job and
> let all the map tasks operate on the same restored snapshot. HBase already
> did this via HBASE-18806, we can do something similar. Jira to correct this
> behavior: https://issues.apache.org/jira/browse/PHOENIX-6334
> *The purpose of this Jira* is to resolve this issue immediately by providing
> the ability to the caller to decide whether or not snapshot restore needs to
> be handled externally or internally on the Phoenix side (the buggy approach).
> All other performance suggestions here:
> https://issues.apache.org/jira/browse/PHOENIX-6081
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