fix(cdc): only allow ADD and DROP in auto schema change (#18245)

Author: StrikeW

e2e_test/source/cdc_inline/auto_schema_change_mysql.slt

@@ -42,6 +42,7 @@ distribution key id NULL NULL
 table description rw_customers NULL NULL
 
 
+# add column
 system ok
 mysql -e "
   USE mytest;
@@ -64,6 +65,57 @@ primary key id NULL NULL
 distribution key id NULL NULL
 table description rw_customers NULL NULL
 
+# rename column on upstream will not be replicated, since we do not support rename column
+system ok
+mysql -e "
+  USE mytest;
+  ALTER TABLE customers RENAME COLUMN v1 TO v11;
+  ALTER TABLE customers CHANGE COLUMN v2 v22 decimal(5,2);
+"
+
+sleep 3s
+
+# table schema unchanges, since we reject rename column
+query TTTT
+describe rw_customers;
+----
+id bigint false NULL
+modified timestamp without time zone false NULL
+custinfo jsonb false NULL
+v1 character varying false NULL
+v2 double precision false NULL
+primary key id NULL NULL
+distribution key id NULL NULL
+table description rw_customers NULL NULL
+
+# revert column rename on upstream
+system ok
+mysql -e "
+  USE mytest;
+  ALTER TABLE customers RENAME COLUMN v11 TO v1;
+  ALTER TABLE customers CHANGE COLUMN v22 v2 double(5,2);
+"
+
+# drop columns
+system ok
+mysql -e "
+  USE mytest;
+  ALTER TABLE customers DROP COLUMN modified;
+  ALTER TABLE customers DROP COLUMN v1;
+  ALTER TABLE customers DROP COLUMN v2;
+"
+
+sleep 3s
+
+# modified column should be dropped
+query TTTT
+describe rw_customers;
+----
+id bigint false NULL
+custinfo jsonb false NULL
+primary key id NULL NULL
+distribution key id NULL NULL
+table description rw_customers NULL NULL
 
 statement ok
 drop source mysql_source cascade;

src/connector/src/parser/unified/debezium.rs

@@ -165,7 +165,7 @@ pub fn parse_schema_change(
 ) -> AccessResult<SchemaChangeEnvelope> {
     let mut schema_changes = vec![];
 
-    let upstream_ddl = accessor
+    let upstream_ddl: String = accessor
         .access(&[UPSTREAM_DDL], &DataType::Varchar)?
         .to_owned_datum()
         .unwrap()

src/frontend/src/handler/alter_table_column.rs

@@ -69,6 +69,7 @@ pub async fn replace_table_with_definition(
     Ok(())
 }
 
+/// Used in auto schema change process
 pub async fn get_new_table_definition_for_cdc_table(
     session: &Arc<SessionImpl>,
     table_name: ObjectName,

src/frontend/src/handler/create_table.rs

@@ -1015,6 +1015,7 @@ pub(super) async fn handle_create_table_plan(
                     &constraints,
                     connect_properties.clone(),
                     wildcard_idx.is_some(),
+                    None,
                 )
                 .await?;
 
@@ -1123,6 +1124,8 @@ async fn derive_schema_for_cdc_table(
     constraints: &Vec<TableConstraint>,
     connect_properties: WithOptionsSecResolved,
     need_auto_schema_map: bool,
+    // original table catalog available in auto schema change process
+    original_catalog: Option<Arc<TableCatalog>>,
 ) -> Result<(Vec<ColumnCatalog>, Vec<String>)> {
     // read cdc table schema from external db or parsing the schema from SQL definitions
     if need_auto_schema_map {
@@ -1154,10 +1157,20 @@ async fn derive_schema_for_cdc_table(
             table.pk_names().clone(),
         ))
     } else {
-        Ok((
-            bind_sql_columns(column_defs)?,
-            bind_sql_pk_names(column_defs, constraints)?,
-        ))
+        let columns = bind_sql_columns(column_defs)?;
+        // For table created by `create table t (*)` the constraint is empty, we need to
+        // retrieve primary key names from original table catalog if available
+        let pk_names = if let Some(original_catalog) = original_catalog {
+            original_catalog
+                .pk
+                .iter()
+                .map(|x| original_catalog.columns[x.column_index].name().to_string())
+                .collect()
+        } else {
+            bind_sql_pk_names(column_defs, constraints)?
+        };
+
+        Ok((columns, pk_names))
     }
 }
 
@@ -1328,6 +1341,7 @@ pub async fn generate_stream_graph_for_table(
                 &constraints,
                 connect_properties.clone(),
                 false,
+                Some(original_catalog.clone()),
             )
             .await?;
 

src/meta/service/src/ddl_service.rs

@@ -12,12 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::sync::Arc;
 
 use anyhow::anyhow;
 use rand::seq::SliceRandom;
 use rand::thread_rng;
+use risingwave_common::catalog::ColumnCatalog;
 use risingwave_common::util::column_index_mapping::ColIndexMapping;
 use risingwave_connector::sink::catalog::SinkId;
 use risingwave_meta::manager::{EventLogManagerRef, MetadataManager};
@@ -966,6 +967,46 @@ impl DdlService for DdlServiceImpl {
                 .await?;
 
             for table in tables {
+                // Since we only support `ADD` and `DROP` column, we check whether the new columns and the original columns
+                // is a subset of the other.
+                let original_column_names: HashSet<String> = HashSet::from_iter(
+                    table
+                        .columns
+                        .iter()
+                        .map(|col| ColumnCatalog::from(col.clone()).column_desc.name),
+                );
+                let new_column_names: HashSet<String> = HashSet::from_iter(
+                    table_change
+                        .columns
+                        .iter()
+                        .map(|col| ColumnCatalog::from(col.clone()).column_desc.name),
+                );
+                if !(original_column_names.is_subset(&new_column_names)
+                    || original_column_names.is_superset(&new_column_names))
+                {
+                    tracing::warn!(target: "auto_schema_change",
+                                    table_id = table.id,
+                                    cdc_table_id = table.cdc_table_id,
+                                    upstraem_ddl = table_change.upstream_ddl,
+                                    original_columns = ?original_column_names,
+                                    new_columns = ?new_column_names,
+                                    "New columns should be a subset or superset of the original columns, since only `ADD COLUMN` and `DROP COLUMN` is supported");
+                    return Err(Status::invalid_argument(
+                        "New columns should be a subset or superset of the original columns",
+                    ));
+                }
+                // skip the schema change if there is no change to original columns
+                if original_column_names == new_column_names {
+                    tracing::warn!(target: "auto_schema_change",
+                                   table_id = table.id,
+                                   cdc_table_id = table.cdc_table_id,
+                                   upstraem_ddl = table_change.upstream_ddl,
+                                    original_columns = ?original_column_names,
+                                    new_columns = ?new_column_names,
+                                   "No change to columns, skipping the schema change");
+                    continue;
+                }
+
                 let latency_timer = self
                     .meta_metrics
                     .auto_schema_change_latency