[jira] [Commented] (SPARK-3212) Improve the clarity of caching semantics

["Michael Armbrust (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-3212?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14127959#comment-14127959 ] 

Michael Armbrust commented on SPARK-3212:
-----------------------------------------

[~matei] also points out that we should make sure to uncache cached RDDs when the base table is dropped.

> Improve the clarity of caching semantics
> ----------------------------------------
>
>                 Key: SPARK-3212
>                 URL: https://issues.apache.org/jira/browse/SPARK-3212
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>            Reporter: Michael Armbrust
>            Assignee: Michael Armbrust
>            Priority: Blocker
>
> Right now there are a bunch of different ways to cache tables in Spark SQL. For example:
>  - tweets.cache()
>  - sql("SELECT * FROM tweets").cache()
>  - table("tweets").cache()
>  - tweets.cache().registerTempTable(tweets)
>  - sql("CACHE TABLE tweets")
>  - cacheTable("tweets")
> Each of the above commands has subtly different semantics, leading to a very confusing user experience.  Ideally, we would stop doing caching based on simple tables names and instead have a phase of optimization that does intelligent matching of query plans with available cached data.



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