IIRC, the new "spark.sql.hive.caseSensitiveInferenceMode" stuff will only scan all table files only once, and write back the inferred schema to metastore so that we don't need to do the schema inference again.
So technically this will introduce a performance regression for the first query, but compared to branch-2.0, it's not performance regression. And this patch fixed a regression in branch-2.1, which can run in branch-2.0. Personally, I think we should keep INFER_AND_SAVE as the default mode. + [Eric], what do you think? On Sat, Apr 22, 2017 at 1:37 AM, Michael Armbrust <mich...@databricks.com> wrote: > Thanks for pointing this out, Michael. Based on the conversation on the > PR <https://github.com/apache/spark/pull/16944#issuecomment-285529275> > this seems like a risky change to include in a release branch with a > default other than NEVER_INFER. > > +Wenchen? What do you think? > > On Thu, Apr 20, 2017 at 4:14 PM, Michael Allman <mich...@videoamp.com> > wrote: > >> We've identified the cause of the change in behavior. It is related to >> the SQL conf key "spark.sql.hive.caseSensitiveInferenceMode". This key >> and its related functionality was absent from our previous build. The >> default setting in the current build was causing Spark to attempt to scan >> all table files during query analysis. Changing this setting to NEVER_INFER >> disabled this operation and resolved the issue we had. >> >> Michael >> >> >> On Apr 20, 2017, at 3:42 PM, Michael Allman <mich...@videoamp.com> wrote: >> >> I want to caution that in testing a build from this morning's branch-2.1 >> we found that Hive partition pruning was not working. We found that Spark >> SQL was fetching all Hive table partitions for a very simple query whereas >> in a build from several weeks ago it was fetching only the required >> partitions. I cannot currently think of a reason for the regression outside >> of some difference between branch-2.1 from our previous build and >> branch-2.1 from this morning. >> >> That's all I know right now. We are actively investigating to find the >> root cause of this problem, and specifically whether this is a problem in >> the Spark codebase or not. I will report back when I have an answer to that >> question. >> >> Michael >> >> >> On Apr 18, 2017, at 11:59 AM, Michael Armbrust <mich...@databricks.com> >> wrote: >> >> Please vote on releasing the following candidate as Apache Spark version >> 2.1.1. The vote is open until Fri, April 21st, 2018 at 13:00 PST and >> passes if a majority of at least 3 +1 PMC votes are cast. >> >> [ ] +1 Release this package as Apache Spark 2.1.1 >> [ ] -1 Do not release this package because ... >> >> >> To learn more about Apache Spark, please see http://spark.apache.org/ >> >> The tag to be voted on is v2.1.1-rc3 >> <https://github.com/apache/spark/tree/v2.1.1-rc3> (2ed19cff2f6ab79 >> a718526e5d16633412d8c4dd4) >> >> List of JIRA tickets resolved can be found with this filter >> <https://issues.apache.org/jira/browse/SPARK-20134?jql=project%20%3D%20SPARK%20AND%20fixVersion%20%3D%202.1.1> >> . >> >> The release files, including signatures, digests, etc. can be found at: >> http://home.apache.org/~pwendell/spark-releases/spark-2.1.1-rc3-bin/ >> >> Release artifacts are signed with the following key: >> https://people.apache.org/keys/committer/pwendell.asc >> >> The staging repository for this release can be found at: >> https://repository.apache.org/content/repositories/orgapachespark-1230/ >> >> The documentation corresponding to this release can be found at: >> http://people.apache.org/~pwendell/spark-releases/spark-2.1.1-rc3-docs/ >> >> >> *FAQ* >> >> *How can I help test this release?* >> >> If you are a Spark user, you can help us test this release by taking an >> existing Spark workload and running on this release candidate, then >> reporting any regressions. >> >> *What should happen to JIRA tickets still targeting 2.1.1?* >> >> Committers should look at those and triage. Extremely important bug >> fixes, documentation, and API tweaks that impact compatibility should be >> worked on immediately. Everything else please retarget to 2.1.2 or 2.2.0. >> >> *But my bug isn't fixed!??!* >> >> In order to make timely releases, we will typically not hold the release >> unless the bug in question is a regression from 2.1.0. >> >> *What happened to RC1?* >> >> There were issues with the release packaging and as a result was skipped. >> >> >> >> >
