Merge pull request #228 from muzarski/table-meta-column

implement `cass_table_meta_column`

Author: muzarski

scylla-rust-wrapper/src/metadata.rs

@@ -32,6 +32,8 @@ pub struct CassTableMeta {
     pub columns_metadata: HashMap<String, CassColumnMeta>,
     pub partition_keys: Vec<String>,
     pub clustering_keys: Vec<String>,
+    /// Non-key columns sorted alphabetically by name.
+    pub non_key_sorted_columns: Vec<String>,
     pub views: HashMap<String, Arc<CassMaterializedViewMeta>>,
 }
 
@@ -81,11 +83,25 @@ pub fn create_table_metadata(table_name: &str, table_metadata: &Table) -> CassTa
             columns_metadata.insert(column_name.clone(), cass_column_meta);
         });
 
+    let mut non_key_sorted_columns = columns_metadata
+        .iter()
+        .filter(|(_, column)| {
+            !matches!(
+                column.column_kind,
+                CassColumnType::CASS_COLUMN_TYPE_PARTITION_KEY
+                    | CassColumnType::CASS_COLUMN_TYPE_CLUSTERING_KEY,
+            )
+        })
+        .map(|(name, _column)| name.to_owned())
+        .collect::<Vec<_>>();
+    non_key_sorted_columns.sort_unstable();
+
     CassTableMeta {
         name: table_name.to_owned(),
         columns_metadata,
         partition_keys: table_metadata.partition_key.clone(),
         clustering_keys: table_metadata.clustering_key.clone(),
+        non_key_sorted_columns,
         views: HashMap::new(),
     }
 }
@@ -209,6 +225,59 @@ pub unsafe extern "C" fn cass_table_meta_column_count(table_meta: *const CassTab
     table_meta.columns_metadata.len() as size_t
 }
 
+#[no_mangle]
+pub unsafe extern "C" fn cass_table_meta_column(
+    table_meta: *const CassTableMeta,
+    index: size_t,
+) -> *const CassColumnMeta {
+    // The order of columns in cpp-driver (and in DESCRIBE TABLE in cqlsh):
+    // 1. partition keys sorted by position <- this is guaranteed by rust-driver.
+    //    Table::partition_keys is a Vector of pk names, sorted by position.
+    // 2. clustering keys sorted by position <- this is guaranteed by rust-driver (same reasoning as above).
+    // 3. remaining columns in alphabetical order <- this is something we need to guarantee.
+    //
+    // Example:
+    // CREATE TABLE t
+    // (
+    //   i int, f int, g int STATIC, b int, c int STATIC, a int, d int, j int, h int,
+    //   PRIMARY KEY( (d, a, j), h, i )
+    // );
+    //
+    // The order should be: d, a, j, h, i, b, c, f, g
+    // First pks by position: d, a, j
+    // Then cks by position: h, i
+    // Then remaining columns alphabetically: b, c, f, g
+
+    let table_meta = RefFFI::as_ref(table_meta);
+    let index = index as usize;
+
+    // Check if the index lands in partition keys. If so, simply return the corresponding column.
+    if let Some(pk_name) = table_meta.partition_keys.get(index) {
+        // unwrap: partition key must exist in columns_metadata. This is ensured by rust-driver.
+        return RefFFI::as_ptr(table_meta.columns_metadata.get(pk_name).unwrap());
+    }
+
+    // Update the index to search in clustering keys
+    let index = index - table_meta.partition_keys.len();
+
+    // Check if the index lands in clustering keys. If so, simply return the corresponding column.
+    if let Some(ck_name) = table_meta.clustering_keys.get(index) {
+        // unwrap: clustering key must exist in columns_metadata. This is ensured by rust-driver.
+        return RefFFI::as_ptr(table_meta.columns_metadata.get(ck_name).unwrap());
+    }
+
+    // Update the index to search in remaining columns
+    let index = index - table_meta.clustering_keys.len();
+
+    table_meta
+        .non_key_sorted_columns
+        .get(index)
+        .map_or(std::ptr::null(), |column_name| {
+            // unwrap: We guarantee that column_name exists in columns_metadata. See `create_table_metadata`.
+            RefFFI::as_ptr(table_meta.columns_metadata.get(column_name).unwrap())
+        })
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn cass_table_meta_partition_key(
     table_meta: *const CassTableMeta,

tests/src/integration/tests/test_schema_metadata.cpp

@@ -254,6 +254,53 @@ CASSANDRA_INTEGRATION_TEST_F(SchemaMetadataTest, KeyspaceMetadata) {
   cass_schema_meta_free(schema_meta);
 }
 
+CASSANDRA_INTEGRATION_TEST_F(SchemaMetadataTest, TableMetadataColumnOrder) {
+  // The order should be: d, a, j, h, i, b, c, f, g
+  // First pks by position: d, a, j
+  // Then cks by position: h, i
+  // Then remaining columns alphabetically: b, c, f, g
+
+  session_.execute(format_string("CREATE TABLE %s "
+    "(i int, f int, g int STATIC, b int, c int STATIC, a int, d int, j int, h int, "
+    "PRIMARY KEY( (d, a, j), h, i ) )", "column_order_test"));
+
+  const CassSchemaMeta* schema_meta = session_.schema_meta();
+
+  const CassKeyspaceMeta* keyspace_meta = cass_schema_meta_keyspace_by_name(schema_meta, keyspace_name_.c_str());
+  ASSERT_TRUE(keyspace_meta);
+
+  const CassTableMeta* table_meta = cass_keyspace_meta_table_by_name(keyspace_meta, "column_order_test");
+  ASSERT_TRUE(table_meta);
+
+  ASSERT_EQ(cass_table_meta_column_count(table_meta), 9u);
+
+  ASSERT_EQ(cass_table_meta_partition_key_count(table_meta), 3u);
+  ASSERT_EQ(cass_table_meta_clustering_key_count(table_meta), 2u);
+
+  auto check_column = [&](size_t index, const char* name) {
+    const CassColumnMeta* column_meta;
+    const char* column_meta_name;
+    size_t column_meta_name_length;
+
+    column_meta = cass_table_meta_column(table_meta, index);
+    ASSERT_TRUE(column_meta);
+    cass_column_meta_name(column_meta, &column_meta_name, &column_meta_name_length);
+    ASSERT_EQ(std::string(column_meta_name, column_meta_name_length), name);
+  };
+
+  check_column(0, "d");
+  check_column(1, "a");
+  check_column(2, "j");
+  check_column(3, "h");
+  check_column(4, "i");
+  check_column(5, "b");
+  check_column(6, "c");
+  check_column(7, "f");
+  check_column(8, "g");
+
+  cass_schema_meta_free(schema_meta);
+}
+
 CASSANDRA_INTEGRATION_TEST_F(SchemaMetadataTest, MetadataIterator) {
   const CassSchemaMeta* schema_meta = session_.schema_meta();