com.datastrato.gravitino.rel

Interface SupportsSchemas

All Known Implementing Classes:

RelationalCatalog

public interface SupportsSchemas

The Catalog interface to support schema operations. If the implemented catalog has schema semantics, it should implement this interface.

Method Summary

Modifier and Type	Method and Description
Schema	alterSchema(NameIdentifier ident, SchemaChange... changes) Apply the metadata change to a schema in the catalog.
Schema	createSchema(NameIdentifier ident, java.lang.String comment, java.util.Map<java.lang.String,java.lang.String> properties) Create a schema in the catalog.
boolean	dropSchema(NameIdentifier ident, boolean cascade) Drop a schema from the catalog.
NameIdentifier[]	listSchemas(Namespace namespace) List schemas under a namespace.
Schema	loadSchema(NameIdentifier ident) Load metadata properties for a schema.
default boolean	schemaExists(NameIdentifier ident) Check if a schema exists.

Method Detail

listSchemas

NameIdentifier[] listSchemas(Namespace namespace)
                      throws NoSuchCatalogException

List schemas under a namespace.

If an entity such as a table, view exists, its parent schemas must also exist and must be returned by this discovery method. For example, if table a.b.t exists, this method invoked as listSchemas(a) must return [a.b] in the result array

Parameters:

namespace - The namespace to list.

Returns:

An array of schema identifier under the namespace.

Throws:

NoSuchCatalogException - If the catalog does not exist.

schemaExists

default boolean schemaExists(NameIdentifier ident)

Check if a schema exists.

If an entity such as a table, view exists, its parent namespaces must also exist. For example, if table a.b.t exists, this method invoked as schemaExists(a.b) must return true.

Parameters:

ident - The name identifier of the schema.

Returns:

True if the schema exists, false otherwise.

createSchema

Schema createSchema(NameIdentifier ident,
                    java.lang.String comment,
                    java.util.Map<java.lang.String,java.lang.String> properties)
             throws NoSuchCatalogException,
                    SchemaAlreadyExistsException

Create a schema in the catalog.

Parameters:

ident - The name identifier of the schema.

comment - The comment of the schema.

properties - The properties of the schema.

Returns:

The created schema.

Throws:

NoSuchCatalogException - If the catalog does not exist.

SchemaAlreadyExistsException - If the schema already exists.

loadSchema

Schema loadSchema(NameIdentifier ident)
           throws NoSuchSchemaException

Load metadata properties for a schema.

Parameters:

ident - The name identifier of the schema.

Returns:

A schema.

Throws:

NoSuchSchemaException - If the schema does not exist (optional).

alterSchema

Schema alterSchema(NameIdentifier ident,
                   SchemaChange... changes)
            throws NoSuchSchemaException

Apply the metadata change to a schema in the catalog.

Parameters:

ident - The name identifier of the schema.

changes - The metadata changes to apply.

Returns:

The altered schema.

Throws:

NoSuchSchemaException - If the schema does not exist.

dropSchema

boolean dropSchema(NameIdentifier ident,
                   boolean cascade)
            throws NonEmptySchemaException

Drop a schema from the catalog. If cascade option is true, recursively drop all objects within the schema.

If the catalog implementation does not support this operation, it may throw UnsupportedOperationException.

Parameters:

ident - The name identifier of the schema.

cascade - If true, recursively drop all objects within the schema.

Returns:

True if the schema exists and is dropped successfully, false otherwise.

Throws:

NonEmptySchemaException - If the schema is not empty and cascade is false.