GitHub user gatorsmile reopened a pull request:
https://github.com/apache/spark/pull/19003
[SPARK-21769] [SQL] Add a table-specific option for always respecting
schemas inferred/controlled by Spark SQL
## What changes were proposed in this pull request?
For Hive-serde tables, we always respect the schema stored in Hive
metastore, because the schema could be altered by the other engines that share
the same metastore. Thus, we always trust the metastore-controlled schema for
Hive-serde tables when the schemas are different (without considering the
nullability and cases). However, in some scenarios, Hive metastore also could
INCORRECTLY overwrite the schemas when the serde and Hive metastore built-in
serde are different.
The proposed solution is to introduce a table-specific option for such
scenarios. For a specific table, users can make Spark always respect
Spark-inferred/controlled schema instead of trusting metastore-controlled
schema. By default, we trust Hive metastore-controlled schema.
## How was this patch tested?
Added a cross-version test case
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/gatorsmile/spark respectSparkSchema
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/19003.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 #19003
----
commit 4c7349f5d7cef703e11d93e114c8361a940e8bfa
Author: gatorsmile <gatorsm...@gmail.com>
Date: 2017-08-20T03:17:12Z
fix.
commit 36339c809a086fb1bb94ec167bf2fa9e4169aca1
Author: gatorsmile <gatorsm...@gmail.com>
Date: 2017-08-22T18:22:26Z
fix.
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