srowen commented on a change in pull request #24221: [SPARK-27248][SQL] refresh table should recreate cache with same cache name URL: https://github.com/apache/spark/pull/24221#discussion_r276242174
########## File path: docs/sql-migration-guide-upgrade.md ########## @@ -50,6 +50,8 @@ license: | - In Spark version 2.4 and earlier, JSON datasource and JSON functions like `from_json` convert a bad JSON record to a row with all `null`s in the PERMISSIVE mode when specified schema is `StructType`. Since Spark 3.0, the returned row can contain non-`null` fields if some of JSON column values were parsed and converted to desired types successfully. + - Refreshing a cached table would trigger a table uncache operation and then a table cache (lazily) operation. In Spark version 2.4 and earlier, the cache name ane cache storage level are not preserved before the uncache operation. Therefore, the cache name and cache storage level could be changed unexpectedly. Since Spark 3.0, cache name and cache storage level will be first preserved for cache recreation. It helps to maintain a consistent cache behavior upon table refreshing. Review comment: It's a good question -- I had assumed the cached name is visible to the user, but is that true? if it is it's worth a release note ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
