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From "Alex Behm (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4172/IMPALA-3653: Improvements to block metadata loading
Date Wed, 30 Nov 2016 05:14:40 GMT
Alex Behm has posted comments on this change.

Change subject: IMPALA-4172/IMPALA-3653: Improvements to block metadata loading
......................................................................


Patch Set 12: Code-Review+1

(7 comments)

I'm pretty happy with the changes. Let's let Dimitris take a look.

http://gerrit.cloudera.org:8080/#/c/5148/12//COMMIT_MSG
Commit Message:

Line 15: We loop throuh each and every file in the table/partition directories
through


Line 17: This results in large no. of RPC calls to namenode, especially with
no. -> number

to the NameNode

especially for large tables


Line 35: 
mention the behavior change of REFRESH


http://gerrit.cloudera.org:8080/#/c/5148/12/fe/src/main/java/org/apache/impala/catalog/DiskIdMapper.java
File fe/src/main/java/org/apache/impala/catalog/DiskIdMapper.java:

Line 31:  * - To maintain consistent mapping across all the table instances so that the disk
thread
... a consistent mapping ... so that the assignment of scan ranges to I/O threads is balanced
and consistent for all scans on the same host.


http://gerrit.cloudera.org:8080/#/c/5148/12/fe/src/main/java/org/apache/impala/catalog/HdfsTable.java
File fe/src/main/java/org/apache/impala/catalog/HdfsTable.java:

Line 288:    * Queries the filesystem to load the file block metadata (e.g. DFS blocks) for
the
Suggest rephrasing:

Drops and re-loads the block metadata for all partitions in 'partsByPath' whose location is
under the given 'dirPath'. It involves the following steps:
...


Line 296:    *   and enumerate all its blocks and their corresponding hosts and disk IDs.
remove part about disk ids, I think that's the next point


Line 778:     LOG.debug("partsByPath size: " + partsByPath.size());
check log lvl


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ie127658172e6e70dae441374530674a4ac9d5d26
Gerrit-PatchSet: 12
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Bharath Vissapragada <bharathv@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Bharath Vissapragada <bharathv@cloudera.com>
Gerrit-Reviewer: Mostafa Mokhtar <mmokhtar@cloudera.com>
Gerrit-HasComments: Yes

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