JingsongLi commented on code in PR #370:
URL: https://github.com/apache/paimon-rust/pull/370#discussion_r3389050453
##########
crates/paimon/src/spec/schema.rs:
##########
@@ -127,27 +127,153 @@ impl TableSchema {
}
/// Apply a list of schema changes and return a new schema with
incremented ID.
+ ///
+ /// Column-level changes operate on **top-level** columns only: a
+ /// `field_names` path with more than one element (a nested struct field)
is
+ /// rejected with [`crate::Error::Unsupported`].
+ ///
+ /// Column errors ([`crate::Error::ColumnNotExist`] /
+ /// [`crate::Error::ColumnAlreadyExist`]) are returned with an empty table
+ /// name; the calling catalog fills in the table's full name.
pub fn apply_changes(&self, changes: Vec<crate::spec::SchemaChange>) ->
crate::Result<Self> {
+ use crate::spec::SchemaChange;
+
+ // Column errors carry no table name here; the catalog layer fills it
in.
+ let full_name = "";
+
let mut new_schema = self.clone();
new_schema.id += 1;
new_schema.time_millis = chrono::Utc::now().timestamp_millis();
+ // Operate on an owned field list, then write it back.
+ let mut fields = std::mem::take(&mut new_schema.fields);
+ let mut highest_field_id = new_schema.highest_field_id;
+
for change in changes {
match change {
- crate::spec::SchemaChange::SetOption { key, value } => {
+ SchemaChange::SetOption { key, value } => {
new_schema.options.insert(key, value);
}
- crate::spec::SchemaChange::RemoveOption { key } => {
+ SchemaChange::RemoveOption { key } => {
new_schema.options.remove(&key);
}
- other => {
- return Err(crate::Error::Unsupported {
- message: format!("Schema change not yet supported:
{other:?}"),
- });
+ SchemaChange::UpdateComment { comment } => {
+ new_schema.comment = comment;
+ }
+ SchemaChange::AddColumn {
+ field_names,
+ data_type,
+ comment,
+ column_move,
+ } => {
+ let name = top_level_field(&field_names)?;
+ if field_index(&fields, name).is_some() {
+ return Err(crate::Error::ColumnAlreadyExist {
+ full_name: full_name.to_string(),
+ column: name.to_string(),
+ });
+ }
+ highest_field_id += 1;
+ let field = DataField::new(highest_field_id,
name.to_string(), data_type)
Review Comment:
This adds the requested type directly to the table schema. That misses two
invariants that Java applies when adding a column: NOT NULL columns are
rejected, and nested field IDs are reassigned from the table-wide
highestFieldId. As written, ALTER TABLE can add `INT NOT NULL` columns whose
existing rows have no value, and can add ROW/ARRAY/MAP-with-ROW columns whose
nested DataField IDs collide with existing field IDs because the SchemaBuilder
assignment path is bypassed. Please reject non-nullable add-column types and
assign/recompute nested field IDs before storing the field.
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