GitHub user marmbrus opened a pull request:
https://github.com/apache/spark/pull/8285
[SPARK-10093][SQL] Avoid transformation on executors.
This is kind of a weird case, but given a sufficiently complex query plan
(in this case a `TungstenProject` with an `Exchange` underneath), we could have
NPEs on the executors due to the time when we were calling
`transformAllExpressions`
In general we should ensure that all transformations occur on the driver
and not on the executors. Some reasons for avoid executor side transformations
include:
- (this case) Some operator constructors require state such as access to
the Spark/SQL conf so doing a `makeCopy` on the executor can fail.
- (unrelated reason for avoid executor transformations) `ExprIds` are
calculated using an atomic integer, so you can violate their uniqueness
constraint by constructing them anywhere other than the driver.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/marmbrus/spark transformDriver
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/8285.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #8285
----
commit 8d3b048f05234da6379a228e73bbebafd1dc97dc
Author: Michael Armbrust <mich...@databricks.com>
Date: 2015-08-18T20:19:39Z
[SPARK-10093][SQL] Avoid transformation on executors.
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