cloud-fan commented on code in PR #38823:
URL: https://github.com/apache/spark/pull/38823#discussion_r1043086633
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sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/TableProvider.java:
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@@ -93,4 +93,18 @@ default Transform[]
inferPartitioning(CaseInsensitiveStringMap options) {
default boolean supportsExternalMetadata() {
return false;
}
+
+ /**
+ * Returns true if the source supports defining generated columns upon table
creation in SQL.
+ * When false: any create/replace table statements with a generated column
defined in the table
+ * schema will throw an exception during analysis.
+ *
+ * A generated column is defined with syntax: {@code colName colType
GENERATED ALWAYS AS (expr)}
+ * The generation expression is stored in the column metadata with key
"generationExpression".
+ *
+ * Override this method to allow defining generated columns in
create/replace table statements.
+ */
+ default boolean supportsGeneratedColumnsOnCreation() {
Review Comment:
Then I think it's `TableCatalog`'s responsibility to decide if a table
supports generated column or not.
1. For general catalogs like HMS, it may need to resolve the table provider
name to `TableProvider`. Then it makes sense to add a new API to
`TableProvider`.
2. For dedicated catalogs like JDBC catalog, it doesn't even have table
provider. It depends on the remote SQL database and `TableCatalog` needs a new
API to indicate it.
How about we add the new API to both `TableCatalog` and `TableProvider`?
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