Github user liancheng commented on the pull request:
https://github.com/apache/spark/pull/4382#issuecomment-73761370
@chenghao-intel The biggest problem issue I see in this PR is that users
can not share cached tables any more, which breaks many existing use scenarios.
I'm afraid it may require major efforts to support both multi-session and cache
sharing. I can think of two alternatives:
1. All sessions share a single `HiveContext` to enable cache sharing, and
provide one `SQLConf` per session to isolate session configurations.
2. Provide one `HiveContext` per session to isolate session configuration,
but extract cached table meta data management out of `SQLContext` /
`HiveContext` to some global place, so that different `HiveContext` can figure
out the mapping between cached tables (actually query plans) and their
underlying materialized in-memory columnar RDDs).
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