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From "Marcel Kornacker (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4172: Switch to BlockLocation methods for disk IDs
Date Fri, 04 Nov 2016 23:27:56 GMT
Marcel Kornacker has posted comments on this change.

Change subject: IMPALA-4172: Switch to BlockLocation methods for disk IDs
......................................................................


Patch Set 1:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/4914/1/fe/src/main/java/org/apache/impala/catalog/HdfsTable.java
File fe/src/main/java/org/apache/impala/catalog/HdfsTable.java:

Line 379:   private static int getDiskId(String storageId) {
> In the BE we mod the disk id to determine which disk queue to put reads on,
it's very unusual for a server to have more than 128 disks (i don't think we've ever seen
one), so from that perspective i'm not worried about using fewer bits to represent the disk
"ordinal".

keep in mind that we really don't care about distinguishing disks globally. using a designated
"out of range" value (such as 127) if a node should really exceed 127 disks, and then placing
scan ranges with that value on random disk queues should degrade performance gracefully in
cases where the number of disks is just a bit above that threshold.


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ibbff94cef9a9db7b3945f8e7b0286866d2cc3b61
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Laszlo Gaal <laszlo.gaal@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Laszlo Gaal <laszlo.gaal@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-HasComments: Yes

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