Aman Sinha has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/16792 )

Change subject: IMPALA-10360: Allow simple limit to be treated as sampling hint
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Patch Set 7:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/16792/5/fe/src/main/java/org/apache/impala/analysis/SelectStmt.java
File fe/src/main/java/org/apache/impala/analysis/SelectStmt.java:

http://gerrit.cloudera.org:8080/#/c/16792/5/fe/src/main/java/org/apache/impala/analysis/SelectStmt.java@223
PS5, Line 223: // for single table query blocks, limit push
> Thanks for the explanation. Yes, I am totally fine with non-sampling based
I am doing that check in HdfsPartitionPruner.pruneForSimpleLimit() line #208:
      if (tblRef.hasConvertLimitToSampleHint()) {.
That will make sure that even in the single table case, do the sampling only if 
the hint is present. Were you wanting that check to be applied here ? Given the 
way the code is structured, checking for that hint here will cause the other 
(non-sample) optimization to be skipped which is not what we want.



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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: Ife05a5343c913006f7659949b327b63d3f10c04b
Gerrit-Change-Number: 16792
Gerrit-PatchSet: 7
Gerrit-Owner: Aman Sinha <amsi...@cloudera.com>
Gerrit-Reviewer: Aman Sinha <amsi...@cloudera.com>
Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Gerrit-Reviewer: Qifan Chen <qc...@cloudera.com>
Gerrit-Reviewer: Shant Hovsepian <sh...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Comment-Date: Tue, 08 Dec 2020 01:21:12 +0000
Gerrit-HasComments: Yes

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