GitHub user ericl opened a pull request: https://github.com/apache/spark/pull/17749
[SPARK-20450] [SQL] Unexpected first-query schema inference cost with 2.1.1 ## What changes were proposed in this pull request? https://issues.apache.org/jira/browse/SPARK-19611 fixes a regression from 2.0 where Spark silently fails to read case-sensitive fields missing a case-sensitive schema in the table properties. The fix is to detect this situation, infer the schema, and write the case-sensitive schema into the metastore. However this can incur an unexpected performance hit the first time such a problematic table is queried (and there is a high false-positive rate here since most tables don't actually have case-sensitive fields). This PR changes the default to NEVER_INFER (same behavior as 2.1.0). In 2.2, we can consider leaving the default to INFER_AND_SAVE. ## How was this patch tested? Unit tests. You can merge this pull request into a Git repository by running: $ git pull https://github.com/ericl/spark spark-20450 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/spark/pull/17749.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 #17749 ---- commit 4c0ff63044199f59ae25ce887485c16b4b83e663 Author: Eric Liang <e...@databricks.com> Date: 2017-04-24T19:28:11Z [SPARK-20450] [SQL] Unexpected first-query schema inference cost with 2.1.1 RC ---- --- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. --- --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org