Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/14207#discussion_r71363705
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/catalog/Catalog.scala ---
@@ -223,6 +223,9 @@ abstract class Catalog {
* If this table is cached as an InMemoryRelation, drop the original
cached version and make the
* new version cached lazily.
*
+ * If the table's schema is inferred at runtime, infer the schema again
and update the schema
--- End diff --
cc @rxin, I'm thinking of what's the main reason to allow inferring the
table schema at run time. IIRC, it's mainly because we wanna save some typing
when creating data source table by SQL string, which usually have very long
schema, e.g. json files.
If this is true, then the table schema is not supposed to change. If users
do wanna change it, I'd argue that it's a different table, users should drop
this table and create a new one. Then we don't need to make `refresh table`
support schema changing and thus don't need to store the
`DATASOURCE_SCHEMA_ISINFERRED` flag.
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