Github user xuchuanyin commented on the pull request:
https://github.com/apache/carbondata/commit/79feac96ae789851c5ad7306a7acaaba25d8e6c9#commitcomment-23407541
In integration/spark2/src/main/scala/org/apache/spark/sql/hive/CarbonFileMetastore.scala:
In integration/spark2/src/main/scala/org/apache/spark/sql/hive/CarbonFileMetastore.scala on line 481:
@jackylk @sraghunandan Hi, Iâm studying the query related code and find this line of code may cause a problem.
The member variable `metadata.tablesMeta` in `CarbonFileMetaStore` is a list based, not Guava-Cache-like based. The action in `refreshCache` will emptied the list but there is no corresponding action to fulfill it.
For example, in `CarbonSessionState.refreshRelationFromCache(...)`, it firstly calls `checkSchemasModifiedTimeAndReloadTables`, which calls `refreshCache` internally.
And then it will call `getTableFromMetadataCache`, which just does a search in `metadata.tablesMeta`. But the value of `metadata.tablesMeta` is empty.
As a result, `CarbonSessionState.refreshRelationFromCache` actually does nothing.
I haven't test it due to lack of environment. Could you review this and correct me if I am wrong.
Ps: Keeping the `loadMetaData(...)` here is OK in my environment.
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