sunchao commented on code in PR #38823:
URL: https://github.com/apache/spark/pull/38823#discussion_r1043667401
##########
sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/TableProvider.java:
##########
@@ -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.
+ *
Review Comment:
nit: add `<p>` between the paragraphs
##########
sql/catalyst/src/main/java/org/apache/spark/sql/connector/catalog/TableProvider.java:
##########
@@ -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:
Yea I'm not sure if the `TableProvider` is a good place for this, since it's
only used by data sources who don't have a real catalog. For instance, Iceberg
doesn't use it in the general case I think, cc @aokolnychyi @RussellSpitzer
What about `TableCapability`?
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