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From "Sailesh Mukil (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-4611: Checking perms on S3 files is a very expensive no-op
Date Fri, 09 Dec 2016 23:21:19 GMT
Sailesh Mukil has uploaded a new change for review.

  http://gerrit.cloudera.org:8080/5449

Change subject: IMPALA-4611: Checking perms on S3 files is a very expensive no-op
......................................................................

IMPALA-4611: Checking perms on S3 files is a very expensive no-op

We call getPermissions() on partition directories to find out if
Impala has access to those files. On S3, this currently is a no-op
as the S3A connector does not try to set/get the permissions for S3
objects. So, it always returns the default set of permissions -> 777.
However, it still makes a roundtrip to S3 causing a slow down in the
Catalog.

We can return the READ_WRITE permission immediately if we know we are
accessing an S3 file, thereby avoiding the round trip to S3 for every
partition. This will greatly speedup metadata operations for S3 tables
and partitions, which is already known to be a big bottleneck.

If and when the S3A connector is able to manage permissions in
the future, we need to revisit this code. However, as permissions on
S3 are unsupported by Impala right now, we might as well gain on perf.

Change-Id: If9d1072c185a6162727019cdf1cb34d7f3f1c75c
---
M fe/src/main/java/org/apache/impala/catalog/HdfsTable.java
1 file changed, 9 insertions(+), 0 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/49/5449/1
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Gerrit-MessageType: newchange
Gerrit-Change-Id: If9d1072c185a6162727019cdf1cb34d7f3f1c75c
Gerrit-PatchSet: 1
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Sailesh Mukil <sailesh@cloudera.com>

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