private static List<String> getPkNames(@Nullable TableChange tableSchema) {
        if (tableSchema == null) {
            return null;
        }
        return tableSchema.getTable().primaryKeyColumnNames();
    }
get primary key names

@param tableSchema table schema
@return primary key column names
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/postgres-cdc/src/main/java/org/apache/inlong/sort/cdc/postgres/table/PostgreSQLReadableMetaData.java