Add namespace_exists method (#2972)

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Closes #2969 

# Rationale for this change
We should make `namespace_exists` available on every catalog. 

## Are these changes tested?
Includes unit tests. Many catalogs have a private method doing this
already. Look at all of the type exceptions being deleted!

## Are there any user-facing changes?
- Adds namespace_exists method.

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Author: rambleraptor

pyiceberg/catalog/__init__.py

@@ -470,6 +470,17 @@ def view_exists(self, identifier: str | Identifier) -> bool:
             bool: True if the view exists, False otherwise.
         """
 
+    @abstractmethod
+    def namespace_exists(self, namespace: str | Identifier) -> bool:
+        """Check if a namespace exists.
+
+        Args:
+            namespace (str | Identifier): Namespace identifier.
+
+        Returns:
+            bool: True if the namespace exists, False otherwise.
+        """
+
     @abstractmethod
     def register_table(self, identifier: str | Identifier, metadata_location: str) -> Table:
         """Register a new table using existing metadata.
@@ -845,6 +856,21 @@ def table_exists(self, identifier: str | Identifier) -> bool:
         except NoSuchTableError:
             return False
 
+    def namespace_exists(self, namespace: str | Identifier) -> bool:
+        """Check if a namespace exists.
+
+        Args:
+            namespace (str | Identifier): Namespace identifier.
+
+        Returns:
+            bool: True if the namespace exists, False otherwise.
+        """
+        try:
+            self.load_namespace_properties(namespace)
+            return True
+        except NoSuchNamespaceError:
+            return False
+
     def purge_table(self, identifier: str | Identifier) -> None:
         table = self.load_table(identifier)
         self.drop_table(identifier)

pyiceberg/catalog/noop.py

@@ -122,5 +122,8 @@ def list_views(self, namespace: str | Identifier) -> list[Identifier]:
     def view_exists(self, identifier: str | Identifier) -> bool:
         raise NotImplementedError
 
+    def namespace_exists(self, namespace: str | Identifier) -> bool:
+        raise NotImplementedError
+
     def drop_view(self, identifier: str | Identifier) -> None:
         raise NotImplementedError

pyiceberg/catalog/sql.py

@@ -204,7 +204,7 @@ def create_table(
 
         namespace_identifier = Catalog.namespace_from(identifier)
         table_name = Catalog.table_name_from(identifier)
-        if not self._namespace_exists(namespace_identifier):
+        if not self.namespace_exists(namespace_identifier):
             raise NoSuchNamespaceError(f"Namespace does not exist: {namespace_identifier}")
 
         namespace = Catalog.namespace_to_string(namespace_identifier)
@@ -251,7 +251,7 @@ def register_table(self, identifier: str | Identifier, metadata_location: str) -
         namespace_tuple = Catalog.namespace_from(identifier)
         namespace = Catalog.namespace_to_string(namespace_tuple)
         table_name = Catalog.table_name_from(identifier)
-        if not self._namespace_exists(namespace):
+        if not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace does not exist: {namespace}")
 
         with Session(self.engine) as session:
@@ -361,7 +361,7 @@ def rename_table(self, from_identifier: str | Identifier, to_identifier: str | I
         to_namespace_tuple = Catalog.namespace_from(to_identifier)
         to_namespace = Catalog.namespace_to_string(to_namespace_tuple)
         to_table_name = Catalog.table_name_from(to_identifier)
-        if not self._namespace_exists(to_namespace):
+        if not self.namespace_exists(to_namespace):
             raise NoSuchNamespaceError(f"Namespace does not exist: {to_namespace}")
         with Session(self.engine) as session:
             try:
@@ -495,7 +495,7 @@ def commit_table(
             metadata=updated_staged_table.metadata, metadata_location=updated_staged_table.metadata_location
         )
 
-    def _namespace_exists(self, identifier: str | Identifier) -> bool:
+    def namespace_exists(self, identifier: str | Identifier) -> bool:
         namespace_tuple = Catalog.identifier_to_tuple(identifier)
         namespace = Catalog.namespace_to_string(namespace_tuple, NoSuchNamespaceError)
         namespace_starts_with = namespace.replace("!", "!!").replace("_", "!_").replace("%", "!%") + ".%"
@@ -537,7 +537,7 @@ def create_namespace(self, namespace: str | Identifier, properties: Properties =
         Raises:
             NamespaceAlreadyExistsError: If a namespace with the given name already exists.
         """
-        if self._namespace_exists(namespace):
+        if self.namespace_exists(namespace):
             raise NamespaceAlreadyExistsError(f"Namespace {namespace} already exists")
 
         if not properties:
@@ -565,7 +565,7 @@ def drop_namespace(self, namespace: str | Identifier) -> None:
             NoSuchNamespaceError: If a namespace with the given name does not exist.
             NamespaceNotEmptyError: If the namespace is not empty.
         """
-        if not self._namespace_exists(namespace):
+        if not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace does not exist: {namespace}")
 
         namespace_str = Catalog.namespace_to_string(namespace)
@@ -593,7 +593,7 @@ def list_tables(self, namespace: str | Identifier) -> list[Identifier]:
         Raises:
             NoSuchNamespaceError: If a namespace with the given name does not exist.
         """
-        if namespace and not self._namespace_exists(namespace):
+        if namespace and not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace does not exist: {namespace}")
 
         namespace = Catalog.namespace_to_string(namespace)
@@ -614,7 +614,7 @@ def list_namespaces(self, namespace: str | Identifier = ()) -> list[Identifier]:
         Raises:
             NoSuchNamespaceError: If a namespace with the given name does not exist.
         """
-        if namespace and not self._namespace_exists(namespace):
+        if namespace and not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace does not exist: {namespace}")
 
         table_stmt = select(IcebergTables.table_namespace).where(IcebergTables.catalog_name == self.name)
@@ -656,7 +656,7 @@ def load_namespace_properties(self, namespace: str | Identifier) -> Properties:
             NoSuchNamespaceError: If a namespace with the given name does not exist.
         """
         namespace_str = Catalog.namespace_to_string(namespace)
-        if not self._namespace_exists(namespace):
+        if not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace {namespace_str} does not exists")
 
         stmt = select(IcebergNamespaceProperties).where(
@@ -681,7 +681,7 @@ def update_namespace_properties(
             ValueError: If removals and updates have overlapping keys.
         """
         namespace_str = Catalog.namespace_to_string(namespace)
-        if not self._namespace_exists(namespace):
+        if not self.namespace_exists(namespace):
             raise NoSuchNamespaceError(f"Namespace {namespace_str} does not exists")
 
         current_properties = self.load_namespace_properties(namespace=namespace)

tests/catalog/test_catalog_behaviors.py

@@ -946,7 +946,7 @@ def test_add_column_with_statement(catalog: Catalog, table_schema_simple: Schema
 
 def test_create_namespace(catalog: Catalog, test_namespace: Identifier, test_table_properties: dict[str, str]) -> None:
     catalog.create_namespace(test_namespace, test_table_properties)
-    assert catalog._namespace_exists(test_namespace)  # type: ignore[attr-defined]
+    assert catalog.namespace_exists(test_namespace)
     assert (Catalog.identifier_to_tuple(test_namespace)[:1]) in catalog.list_namespaces()
     assert test_table_properties == catalog.load_namespace_properties(test_namespace)
 
@@ -1015,16 +1015,16 @@ def test_get_namespace_metadata_raises_error_when_namespace_does_not_exist(catal
 def test_namespace_exists(catalog: Catalog) -> None:
     for ns in [("db1",), ("db1", "ns1"), ("db2", "ns1"), ("db3", "ns1", "ns2")]:
         catalog.create_namespace(ns)
-        assert catalog._namespace_exists(ns)  # type: ignore[attr-defined]
+        assert catalog.namespace_exists(ns)
 
     # `db2` exists because `db2.ns1` exists
-    assert catalog._namespace_exists("db2")  # type: ignore[attr-defined]
+    assert catalog.namespace_exists("db2")
     # `db3.ns1` exists because `db3.ns1.ns2` exists
-    assert catalog._namespace_exists("db3.ns1")  # type: ignore[attr-defined]
+    assert catalog.namespace_exists("db3.ns1")
     # make sure '_' is escaped in the query
-    assert not catalog._namespace_exists("db_")  # type: ignore[attr-defined]
+    assert not catalog.namespace_exists("db_")
     # make sure '%' is escaped in the query
-    assert not catalog._namespace_exists("db%")  # type: ignore[attr-defined]
+    assert not catalog.namespace_exists("db%")
 
 
 # Namespace properties
@@ -1064,7 +1064,7 @@ def test_load_empty_namespace_properties(catalog: Catalog, test_namespace: Ident
 def test_list_namespaces(catalog: Catalog) -> None:
     namespace_list = ["db", "db.ns1", "db.ns1.ns2", "db.ns2", "db2", "db2.ns1", "db%"]
     for namespace in namespace_list:
-        if not catalog._namespace_exists(namespace):  # type: ignore[attr-defined]
+        if not catalog.namespace_exists(namespace):
             catalog.create_namespace(namespace)
 
     ns_list = catalog.list_namespaces()
@@ -1084,7 +1084,7 @@ def test_list_namespaces(catalog: Catalog) -> None:
 def test_list_namespaces_fuzzy_match(catalog: Catalog) -> None:
     namespace_list = ["db.ns1", "db.ns1.ns2", "db.ns2", "db.ns1X.ns3", "db_.ns1.ns2", "db2.ns1.ns2"]
     for namespace in namespace_list:
-        if not catalog._namespace_exists(namespace):  # type: ignore[attr-defined]
+        if not catalog.namespace_exists(namespace):
             catalog.create_namespace(namespace)
 
     assert catalog.list_namespaces("db.ns1") == [("db", "ns1", "ns2")]
@@ -1140,7 +1140,7 @@ def test_update_namespace_metadata(catalog: Catalog, test_namespace: Identifier,
     catalog.create_namespace(test_namespace, test_table_properties)
     new_metadata = {"key3": "value3", "key4": "value4"}
     summary = catalog.update_namespace_properties(test_namespace, updates=new_metadata)
-    assert catalog._namespace_exists(test_namespace)  # type: ignore[attr-defined]
+    assert catalog.namespace_exists(test_namespace)
     assert new_metadata.items() <= catalog.load_namespace_properties(test_namespace).items()
     assert summary.removed == []
     assert sorted(summary.updated) == ["key3", "key4"]
@@ -1154,7 +1154,7 @@ def test_update_namespace_metadata_removals(
     new_metadata = {"key3": "value3", "key4": "value4"}
     remove_metadata = {"key1"}
     summary = catalog.update_namespace_properties(test_namespace, remove_metadata, new_metadata)
-    assert catalog._namespace_exists(test_namespace)  # type: ignore[attr-defined]
+    assert catalog.namespace_exists(test_namespace)
     assert new_metadata.items() <= catalog.load_namespace_properties(test_namespace).items()
     assert remove_metadata.isdisjoint(catalog.load_namespace_properties(test_namespace).keys())
     assert summary.removed == ["key1"]
@@ -1168,13 +1168,13 @@ def test_update_namespace_metadata_removals(
 def test_drop_namespace(catalog: Catalog, table_schema_nested: Schema, test_table_identifier: Identifier) -> None:
     namespace = Catalog.namespace_from(test_table_identifier)
     catalog.create_namespace(namespace)
-    assert catalog._namespace_exists(namespace)  # type: ignore[attr-defined]
+    assert catalog.namespace_exists(namespace)
     catalog.create_table(test_table_identifier, table_schema_nested)
     with pytest.raises(NamespaceNotEmptyError):
         catalog.drop_namespace(namespace)
     catalog.drop_table(test_table_identifier)
     catalog.drop_namespace(namespace)
-    assert not catalog._namespace_exists(namespace)  # type: ignore[attr-defined]
+    assert not catalog.namespace_exists(namespace)
 
 
 def test_drop_namespace_raises_error_when_namespace_does_not_exist(catalog: Catalog) -> None:

tests/integration/test_catalog.py

@@ -410,7 +410,10 @@ def test_concurrent_create_transaction(test_catalog: Catalog, test_schema: Schem
 @pytest.mark.integration
 @pytest.mark.parametrize("test_catalog", CATALOGS)
 def test_create_namespace(test_catalog: Catalog, database_name: str) -> None:
+    assert not test_catalog.namespace_exists(database_name)
+
     test_catalog.create_namespace(database_name)
+    assert test_catalog.namespace_exists(database_name)
     assert (database_name,) in test_catalog.list_namespaces()